what's up you guys it's Adana welcome back to my channel so I wanted to talk to you guys about the panry and the panry LA so I'm not yet ready for a recertification but this is definitely something that I've been thinking about um because y'all like I've been a PA for like almost five years now right when when did I graduate 2019 20 21 22 23 yeah like it's I'm going into my fifth year which is bananas um so uh this is something that I have to like keep at the forefront of my mind because very soon I'm going to be eligible for recertification and if you are already eligible for recertification and you need some help in terms of like you're studying because like it's out the door this video is free so let's get in the video right now all right so let's talk about the panry and the panry LA so the LA is the longitudinal assessment one that's the one that you like do at home you're not going into um an actual like test site to sit down and do the test right and so uh it sends you like a certain number of questions each month and you fill out the question over a period of time um and then you know they give you your assessment on whether or not you pass that block and like if you pass the block you move on to the next block so that is the panry LA aspect and the panry is just your typical panry that you you go in just kind of like similar to the pants you go in you sit down in a testing mode and you take the exam now um obviously just like with any board exam um recertification is very stressful and you need help you need like resources and tools to help you get through okay so I'm here to provide that for you uh Ross review has created a panry and a panry LA cubing now I I love Ross review I've always said this you guys and I just love the fact that they continue to grow with us as a PA profession in terms of our standardized testing and the things that we're learning the things that we need to know um and then you know they keep providing resources for us and this resource is something for you know your season PA that needs to recertify and if you are trying to recertify and you're like man I don't remember like the the murmurs right you know like I I'm a PA in women's health right close to home I'm a PA in women's health and I don't really deal with like the heart murmurs like that um so I don't remember like the love dubs in terms of like where I hear like is it sy s2 or anything like that this will help you with that because it it gives you over 2000 questions you have access to over 2000 questions um of all the different subjects in terms of like musculoskeletal and peas and women's health and emergency medicine and cardiology you know the things that and the specialties and areas that you don't necessarily work in on a consistent daily basis but you will be expected to know and be tested on when you're doing your recertification so this does that um and it's really nice because you also get a like you get cme credit uh you do get your category one cme credit if you take the standard or the premium package so there are three different package basic standard and premium they come at different price things 399 589 689 um and the pricing obviously like the jump in price gets you more things so you continue to get like your questions your over 2000 questions and your uncommon delights which are those like extra added little bonuses right but at the standard package you get your 100 um AMA category one cme credits which is amazing because you need that to keep your certification and speaking of like I have to like finish my certification for this year because again like I'm about to be like I'm like I'm gonna be like a teen a teenager pa no longer a baby pa mi so uh that's actually pretty cool um but yes anyway so standard is 589 you get your 100 cme category one credits and then if you go to the premium aspect of things you get everything that you got in the standard but you also get um like an AME self-assessment with 20 cme credits um and then you get like a little bonus of a thousand additional questions and so uh in all like for the premium you're getting over 3000 questions and then in this standard you're just getting like you know the 2000 questions so uh it's very very nice um I I love the aspect of just being able able to continuously have um I guess you can say access to all of like the newest not only treatments but like how to like source out these various different diseases right and just being able to kind of like remember and retrain yourself to be like oh okay yes I do remember that and that's what that was saying that was what that was talking about and I do remember this from you know 10 15 years ago when I was in pa school um and now I I get it and this is making sense to me and I can grasp this for my recidification so if you are interested or if you are in like the mode of I need to figure out what I'm doing for recertification I absolutely suggest this because it comes with a free trial so you can try it free for 10 days and that's like an ample amount enough time for you to actually as you know do a really good assessment of the product and see if this is something that is going to be beneficial to you and your learning okay so like don't even like really think about it just do it like Nike okay just go ahead start that free trial and if after the free trial which I know you will actually see the benefit of it but if after the free trial you see the benefit of it then go ahead and purchase the package that works best for you all right if you have any questions for me you guys know what to do leave a comment section below don't forget to like and subscribe follow my instagram on no follow me at instagram on adon follow me at instagram no follow me on instagram at adon the pa and on instagram at get that's the university thank you guys so much for watching I will talk to you guys next time what is going on I'll talk to you guys next time bye


We went all in the hotel, planted cover crops and started rotational grazing here in the last five years. Really intensified our rotational grazing and use of cover crop. That's made a huge difference. Yeah, the cows are in a smaller area, so the rest of the pastures have all got time to grow. It's just improved our lives in so many different ways. Time management, efficiency, profitability, and just improving the water infiltration and the holding capacity.


is to have CPI less than 1. And the primary way to achieve that is to reorder instructions to reduce the number of interruptions. So, we have discussed the technique of dynamic So, here is a summary of the major elements of dynamically scheduled pipeline. You need a good branch predictor to make sure that the later part of the pipeline works on useful instructions and minimize the wasted work. Otherwise, you do not have a good predictor, you will be fetching wrong instructions most of the time and you will be doing wasteful work, which will have to be thrown away later. Second element is multiple issue. You must fetch, decode, select and issue multiple instructions in this cycle and that is what is called a super scalar processor. Third element is wake up logic. So, this logic is responsible for waking up instructions that are waiting for values. So, it preserves data flow and the implementation of the wake up logic is essentially a bank of comparatives. Next one is selection logic, which essentially selects a subset of instructions that can execute that. And there could be two possibilities of selection. You could select in order or you could select out of order instructions. So, we will look at both of these very soon. In fact, we have already looked at out of order selection. The only constraint, the extra constraint for out of order selection is giving a priority mechanism or often called a time breaker. For example, if you have decided that you design your hardware such that in a cycle maximum you can issue 10 instructions. Now, it could be possible that you have 20 instructions ready. Now, out of order selection of course, does not impose any constraint on which instructions you can pick. You can pick any 10 of these. So, there has to be a time breaker policy. Whereas, in order already gives you a restriction that you have to go in order. You cannot violate the order, which means many if you have 20 different instructions at different places which are ready, you may be only able to select out of order. So, we will soon look at this one actually. It is a reconstruction of out of order selection, much similar work performance. So, essentially the idea here is that the selection logic obeys the issue constraints such as available register file reports, memory reports and functional links. So, the example just I mentioned about this 10 instructions maximum that comes from these constants. Because, 10 instructions will possibly mean that your register pipeline has 20 reports. Memory reports may be something depending on how many of these 10 instructions can be memory operations and so on and so forth. And finally, you have decoupled execution and commit. So, this is very different from what we have discussed for single issue in order pipelines.  So, essentially this particular logic preserves in order write back and store computation. So, these are the major elements of dynamic scheduling that we have discussed, which tries to achieve this goal that is CPI as low as possible. So, at each stage, if you observe carefully, you are introducing certain constraints for implementation purpose. For example, here you are saying that I do not have an oracle predictor. I have a realistic predictor, which will make mistakes certain times. That will actually increase the CPI by some amount. Here, you are saying that I cannot really fetch decodance and select an issue and infinite unwanted number of instructions. I have some limit there. That will further reduce increase your CPI. Here, you are saying that I can wake up arbitrary number of instructions, but I cannot really select all of them for each one. So, there are also imposing certain limits. And here, of course, you are saying that I cannot really commit an unwanted number of instructions. They are also imposing some limit. So, all these taking together along with your data flows will give you some CPI, which is hopefully better than whatever we have discussed and whatever we are doing in your book. Any question of this? This basic scheme of dynamic scheduling. So, this actually, this description abstracts away all the implementation details. How exactly you go and implement all these things? These are also discussed. So, just to recap a little bit. So, when you are issuing multiple instructions in a cycle, ideally the CPI should go down by a factor equal to minimum of issue and commitment. So, how many instructions I can execute in a cycle? And how many instructions I can commit in a cycle? Minimum of these should decide by how much my CPI should go down compared to a single issue in order by that. So, assuming full renaming, that is, suppose you have no name dependence, no false dependence. You have only true data flow dependence and a control flow. So, data flow and control flow will only limit the CPI. Also, there could be structural hazards that is insufficient functionalities. And there are two possible selection algorithms, in order selection and out of order selection. This one we have already discussed. So, let us take a look at this one. What really is in order selection? So, this is the simplest possible design of our super scalar processor. By the way, the term super scalar really means that you are executing multiple instructions in a cycle. So, in this case, what you do is you issue the instructions sequentially. So, you scan the issue queue, stop as soon as you come to an instruction which cannot be executed. Which could be possible due to pending operands or insufficient functionalities. So, here is an example. Let us see what is happening here. So, these two are independent instructions. And let us assume that their operands are now ready, are 5, are 6, and are 3 are ready already. This one depends on add. So, it is clear that this one cannot execute together with this one. That is pretty obvious. And these two are also independent. So, an out of order scheduler would actually pick these four instructions except the red one. And would actually execute them in a cycle. And in order scheduler would actually issue only these two in this cycle. Because it cannot violate the order. In the next cycle, it will probably pick up these three and issue them. So, you cannot issue the last two even though they are independent of the first. So, that is what you do is what you do in order issue. And what you gain by doing this simple design in four terms. So, from this list, can you tell me what gets simplified? Wake up logic gets simplified. Why? You still have to wake up the waiting instructions. So, selection logic is not important. Well, the selection logic is the logic which picks instructions and stops at the first reading. So, it is a simpler logic. What else? Do I need this one? In order omit or anything? Yes. In selection logic, we are already choosing like this. So, then how? They do not. Can I modify the registers immediately? So, here we are actually putting the results back to the queue at which and later moving it. Can I do it here? Can I move R4 and R7 directly to registers immediately? Is that possible? Is that possible? Is that possible? Whether it goes to a supply or two stock? Yes, you are very good. I can? Anybody else? So, in two different seems that in order issue should read me off this particular logic in order to commit. Is that right? Sir, the pipeline stages are not the each instruction is not the same. So, let us assume that there is a single pipeline. Every instruction goes to that pipeline. Yes, you are right. Otherwise, there will be problems. Yes. Because essentially, we are talking about for completion problem. Yes. No, let us not get into that. So, different execution units. Right. So, essentially, you are saying that in that case, whatever we have seen is a multi-cycle execution. Some instructions they complete early and they write. No, let us not assume that. We have a single simple pipe stage pipe or whatever. Every instruction goes to the same pipe. The right after right is like there are two statements writing in the same register. Okay. And if the order of then gets changed. Okay. The order of. Okay. So, essentially, you are saying that in the register find right port, I should have some mechanism to maintain the order in which they write. Okay. Is that understandable? For example, these two instructions could be writing both to R4. Okay. I must preserve this order when they write to register find. Okay. Which makes sense. Anything else? Any other issue? Yes. We have branch. Yes. But remember that instructions execute in order. Which means if there is a branch before it, it has already executed. Okay. And I know the fate of it by now. You cannot put anything into the branch. Okay. Now you can say that I probably cannot execute anything together with a branch. That's what we want you to say. Yes. True. Yes. Because anything that goes in parallel with a branch may have a possibility of producing a raw value and productive the register find. Yes. That is true. Yes. Any other issues? The store and door also needs to be independent of them. Time being developed. Sure. Yes. So we follow the same protocol. Yes. Here the things are much simpler because they will go in order. Okay. You know that the execution is in order. If there is a store and the register is a load, you can't figure out that this load is independent of the property. Right. So you are saying that if I have a store and a load, I cannot execute them in parallel in a cycle. That's what it is. Yes. Yes. So we still have certain issue constants as they're coming out here. We also have to maintain register light hold order to detect right after right hazards. Any problem with right after read hazards? Can that create an issue? Right after read dependencies? Okay. All right. So the point here is that it's indeed simple. Okay. It pretty much leads you of the in order extra five stage for in order commit. Provided you maintain certain points that you guys have raised. Okay. And here is an example of order issue. We have already discussed these also. So colors are hopefully clear. Right. We have three colors here. So depends on your test and how you see it. I'll call it a pink. This particular color. Okay. So the pink instructions can go in the first cycle because they're all independent. And you can figure out why the rest cannot go. This one depends on the load. This one depends on the ad. This is independent. This one depends on the XOR. This is also independent. This one depends on the ad and this one depends on the shift. This one is independent. All right. Okay. So these three instructions are independent. They can go in the first cycle. All right. So that's the basic idea of order issue. I don't care about the order. Okay. We have discussed it already. The blue ones can go in the second cycle because the black ones still cannot go because I'm saying that it is a cache list which is essentially meaning that it's going to take a long time to complete. So these three instructions are arithmetic instructions, actually logic instructions. They're complete in a cycle program. Okay. So their dependence can issue in the next cycle. Like this one can issue in the next cycle. This one can issue in the next cycle. Okay. So that's the second issue cycle. And finally, when the load completes, let's see. Okay. In the third cycle, this can go without any problem because both its operands will get ready from these two. Okay. All right. It needs 20 and 19. They come from here and here. And then finally, when the load completes, this will go. And in the next cycle, this will go. So that's the order model issue. And then my commit logic will guarantee that they update registers in the order specified in this program, in this particular signature order. That's the essence of order model issue. Okay. Okay. And we also discussed the presence of this right after read problem, which you have to worry about. As you can see here, right? So we said that the shift can issue in the second cycle. But you have to be sure that it doesn't overwrite R19, which has been consumed by the end instruction much later. Okay. And in order to commit, it solves the problem because we'll make sure that 19 will not get rid of you until all these instructions get a chance to write. Right? So in order to commit, we'll make sure that first R4 is written, then R5, then R10, then R26, then R20, then R27, then R19. Okay. So there's no end dependence problem here. If you commit in order. Okay. But the downside is that you need space to buffer results. Okay. You have to make sure that R19 is not made visible to the other instructions. Okay. So often, people call dynamics scheduling also a form of speculative execution. Because the point here is that you are combining.  So often this part, except the branch predictor, can be used independent of what's happening in the fetcher. Okay. Whether you have a predictor or not, you can definitely use this part of the logic. Okay. So essentially you can say that I'll keep on fetching in order. Okay. No branch predictor. On a branch, whenever I observe a branch, I'll stop. Okay. I can still do this section. Even without a branch predictor. Nothing stops me from using all this logic. Okay. So that's the pure dynamic scheduling. There is no speculation. As soon as you introduce a branch predictor, you're bringing in some speculation in the pipeline. You're now saying that there are certain instructions which are speculatively fetched, which may be actually on the long path. Okay. So eventually the branch predictor's prediction will be tested. And I'll get to know whether the instructions are correct or not. Okay. So these two taken together is often called speculative execution. So there's just a different name of what we have already discussed. So resolve control dependencies by predicting. Continue execution past predicted branches. That is, you not only fetch from predicted path, but also execute them. Okay. So they've already discussed this also. Buffer results in some structure is called a reorder buffer or an active list depending on the processor architecture. So active list is the term used by MIPS architectures. Otherwise, in most other processors, you'll see the term reorder buffer. Okay. This is actually a separate structure which maintains the results of the instructions and order of the instructions. All right. Allocate it together with the issue keyword tree. So in the issue keyword tree, we've put everything that the one that we saw. Here I'm just decoupling a few fiddles from the issue keyword tree, putting in the same structure or the order over, all right? So essentially decouples the value field from the issue key. That's all right. Typically issue key is distributed among different types of functional 도s. These are known as blizzard mission stations. That's what we have discussed also. So, you can say some of the comparisons because all to all comparison is actually not needed for all cases. And finally, you write or commit results register file or memory only when instruction comes to the top of the ROB. So, ROB is an acronym used for view order buffer. So, view order buffer is actually a FIFO queue. It maintains the instructions and it has a value field which stores the result produced by the instruction and it will be drained in order. So, that is essentially that is what we have discussed. It is just that I am just introducing a new structure called ROB to decouple the value field from the issue queue and distributing the issue queue across functional units. So, you can say that you have an issue queue for a point a you will have an issue queue the load store unit the cache will have an issue queue and memory system will have an issue queue. Any question is it there? So, now just one small element that is left in this architecture is something called register renaming. We have already seen this essentially what we were doing was that we are renaming registers into issue queue slots. So, whenever instruction produces a register it is called as this example. So, here essentially R 4 will be renamed to slot ID 0. R 5 will be renamed to slot ID 1. R 10 will be renamed to slot ID 2. So, whenever slot ID 0 is done it has a dependence on slot ID 0 it will be opened up. So, essentially what I am doing is I could actually now rewrite the instructions as follows. I could say load word ID 0 comma 0 R 6 at I ID 1 comma ID 0 comma 0 X 20 and so on and so forth. I can actually translate the instructions to a different in space. Similarly, I could say and ID 2 whenever I get a new instruction I get a new target. I assign it to a new slot ID 1 R 19 XR ID 3 R 2 R 7 sub ID 4 ID 3 etcetera. Now, this earlier this is this is reaming with N is it I am translating the registers from one name space developing the only thing to observe here is that it is a mix of two name spaces. Some of the names are coming from the registers architectural registers some of the names are coming from my queue slot ID. And there will be a table who should maintain this name for example whenever you do this you will say R 4 is now mapped to ID 0. So, that is how you do that. So, that is how we have done till now. And here since we have two namespaces we had a problem that is we need to figure out whenever instruction issues where from it should read the back. So, there are two possible places it can read the value from. So, for example, this instruction will read one value from the register 19 in the register part. And because of these two different sources of values we had a problem that we have to wake up cycle at the time of commuting. We make sure to let this instruction know that for example, suppose this instruction suppose this instruction issue got delayed for some reason for some reason whatever it may be. And by the time it issues this instruction has already written back. So, when it writes back it has to tell this instruction that now we should not take the value from ID 0, we should actually take the value from R 4. That has to be now changed back. So, this becomes a huge problem because of the primary reason for this problem is that we have two namespaces mixed up here. We want one namespace that is it. We want all values to come from single namespace. So, that is exactly what today's processors do and that is called register remaining. So, let us try to define a few terms. Is the problem clear? Any question before I move on? So, registers visible to the compiler are called logical or architectural registers. For example, 32 in number from MIPS, the one that you are using for your move on. There are 8 for x86 and this is fixed by the instruction set architect. That is how much registers should be made visible to the compiler or the program. And there are physical registers inside the processor. Usually today it is much larger in number and not visible to the compiler. However, the requirement is that your physical register file size should be at least as large as the logical register file size. So, that in the minimum case you should be able to have a 1 to 1 mapping from one logical register to one physical register. And that is what the processor you are using for your homework actually does. It has 32 logical registers. It has 32 physical registers. There is always a fixed 1 to 1 mapping from a logical register to physical register. But today's processors actually have much larger number of physical registers inside the processor, which are not visible to the compiler. And if you have that essentially then you have to establish the mapping. And the mapping actually changes over time. Which logical register maps to which physical register actually keeps on changing. And that is exactly the algorithm that defines register. The destination logical register of every instruction is assigned a new physical register now. Just like this, except assigning a Q slot ID, I will become a free physical register and give it to the instruction target. The dependence is a tract based on the namespace of physical registers for you. There is no Q slot ID namespace. So, MIPS R 10 K has 32 logical and 64 physical registers. Intel 20 of 4 has 8 logical and 128 physical registers. Today's Intel processors have many more. So, we will see exactly what it means to have more physical registers. Why you want that and so on. So, let us revisit our last example. Let us see how renaming works. So, let us assume that there are 64 physical registers. And this is the currently already renamed registers. So, R 6 currently points to physical register 54, R 19 points to P 38, R 2 points to P 0, R 7 is P 20, R 5 is P 3, R 6 is P 2. So, there will be a table which will maintain these maps. So, I will have a table for MIPS. I will have a table with 32 entries actually 31, because R 0 is actually fixed. It is hardware to 0. So, in this case for example, your let us see R 2. So, this row is for R 2. It will basically hold 0, which means that currently any instruction requiring R 2 should read physical registers 0 and etcetera. So, the first instruction comes. It has a target R 4. So, it should get a new register. Which register should it get? So, there is a free list of registers. There is a feedback to maintain, which register is free. I pick up the first register which is free. So, let us suppose that it is P 15. So, R 4 gets renamed to P 15 and then the instruction finds that R 6 is the source of the register. So, it looks up the map table finds that R 6 is currently mapped to P 54. So, it gets renamed to this. So, when the instruction will finally issue an execute, it will go and read P 54 to get the value and put it in P 15. So, the next instruction comes. It has R 4 as the source looks up the table finds that R 4 is renamed to P 15. So, it changes to P 15 and assigns a new register to R 5. And the process continues. Now, you can see that the registers which had a war problem now get two different names. That problem actually goes away. So, this instruction will read from P 38 because at this point R 19 was mapped to P 38. And here this instruction will get a new register for R 19. Here it cannot be P 38. Why is that? It is not over the handle. It is just that P 38 is not available at this point. It has already been allocated to a register. So, we will soon see how to recycle the registers. So, there will be a mechanism where one will actually recycle the registers. But currently the point is that whenever something gets renamed to a physical register, that physical register is occupied. The subsequent instruction cannot use that register until it is freed. And we will see when are the registers needs. So, it is a basic algorithm. It is very simple. Yes. So, you assign it to a new register. So, every target gets a new register. The new register is the one which is free out of many free registers. So, does this example tell you that you probably need at least one more register, one more physical register than the number of logical registers. If you had exactly same, could I make any progress actually? I would, right? Because at any point in time, all registers will probably be mapped to something. I get a new instruction, nothing is free. I cannot read the other thing. So, to make more progress, I need at least one extra physical register. So, this will formalize this notion that what exactly, how it relates to execution time and performance. Any question on that? All right? So, branch instructions do not have a target. So, they do not get a new register. They only rename their sources. So, R19 becomes P45, because P45 was assigned R19 here. And R20 is taken from here, which is P8. R20 was renamed to P8. But there is nothing, there is no new register assigned to branch. So, you just rename the sources. So, this one now makes sure that everything is a single namespace. And instruction issues, it knows where to read from the value. It reads the value from there and that's it. So, here is another example how renaming solves the problem of right after right hazard. So, here are two instructions that write to the same register R5. So, in this instruction R5 will get renamed to some register, say P50. And here it will get renamed to some other register, say P45, whatever is free. So, now they can actually execute concurrently. They will back to different registers. So, now it is safe to issue them in parallel, because they are actually independent. It is just the compiler gives a shortage of registers, architectural registers that you could use the right after right hazard. So, essentially what I am saying here is that, well actually you could ask the question that the compiler was forced to do this. Why not expose all the registers to the compiler? Why do you have this complicated hardware inside which would do that? If the compiler all the registers that you do, you do a good job of register automation. What do you think? Why is it done in this way? Is the question clear? Right. So, what I am saying is that, see what I am trying to say is why are we doing the name? Because we want to get rid of the name difference. That's the only part. And why do we have the name differences? Because the compiler was probably short of registers. That's why we have to introduce these name differences. Like here, you would very well ask, why the compiler choose R 19 here? It could have chosen a different register, right. And the reason is that probably it didn't have a register.  So, if you give it more registers, it should do a better job. Why is it done in this way? Why internal processors are stuck with each logical registers forever? Sorry, say it. You don't need to know, but you can expect that the compiler will definitely do a better job, give it more registers. There will still be name differences. It is not guaranteed that all name differences will go away, but probably it will be so low in number that it doesn't matter anymore. But it is never done, it will not be done ever. Why is that? Yes. Sir, the ISI would change because of adding new registers. Exactly. So, instructions and articulations have to change. Sorry. Magward compiler. Yes. So, the binaries that are compiled today will not work tomorrow as soon as you do this. Sorry. ISI is going to change. So, you have to recompile all applications, which is possible. Sorry. Second. No, no, no, here is a problem. You have bought a Microsoft office suit, which is compiled for yesterday's 686 and yesterday's. Microsoft is going to issue a new license to you, actually, to all the customers with a new binaries. It is a huge headache for the software industry. So, it is primarily a business angle. Why this is not done? Theoretically, there is no problem. We could do it. So, just to hide this problem, processors are doing it inside in the pipeline. Although I must mention, actually, AMD took an interesting step when they designed Octave. They actually introduced 16 logical registers. And we showed that we actually use them. So, of course, they came with a rider that if you want to make use of this, you have to recompile your binaries, but your old binaries will continue to work with lower probabilities. That's all. So, they are, of course, the native level. Okay. All right. So, registered renaming maintains a map table that records the logical register to physical register map. After an instruction is decoded, its logical register numbers are available. The renamer looks up the map table to find mapping for the logical source registers of this instruction, assigns a free physical register to the registration logical register, and records a new mapping. So, that's the renaming procedure. So, how does the pipeline look like? So, these are my pipeline stages. I'm not saying, really, that each stage is a cycle. So, fetch decode, then rename allocate. So, in the rename allocate stage, you rename your logical registers, source registers, assign a new physical register to the registration. You allocate ROB entry. You allocate issue queue entries. Then you do a selection issue whenever the instruction is ready, eventually it will be ready. Then you read the register file. So, when you read this, you read the physical registers of those. Okay. All right. So, you execute, look up memory immediately, and then retire, commit. We also come to this particular stage, because now the question is, what this stage is really doing? Because previously, we were actually copying values from ROB to the register file. Now, that need is gone, because I can execute. I can write the register immediately, because each instruction now gets a different register. So, there is no question of a write-up to register or write-up to read. I can write the register immediately. That's what that particular stage does. So, fetch decode, rename, allocate are in-order stages.  All right. Select issue, register file, read, execution, memory, look up are out of order. You can execute instructions as and when they become ready. You don't have to obey the order. An instruction directly updates the destination register file. A destination physical register contents on competition doesn't wait until commit. We'll soon argue that this is correct. Although intuitively it is correct, because every instruction gets a new physical register. So, there is no question of a conflict, and also there is no question of write-up to read hazard. So, out of order register update that happens actually now, and you'll have to argue why is it correct. So, this will come to that point. And retire is again in order. So, these are technical term often used for it. That is an instruction retire. So, it means that it was born when it was fetched, and finally it's done. We retire. So, retire is again in order, but multiple instructions may retire each cycle. And register write-back is not part of this. It happens as part of the execution stage. When instruction issues, it broadcasts its destination physical register ID to all instructions in the issue queue, and that's essentially the wake-up logic. So, every instruction will compare its source physical registers with the destination of the broadcast register. So, for example here, when this instruction issues, it will broadcast P 50 to all the instructions. And this guy will have a match, and we'll know that now the next cycle will probably be an issue. In this case, probably count issue in the next cycle will be a low interlock. Probably wait for a few more seconds. Similarly, when this instruction issues, it will broadcast P 62. And this instruction will match its source, and we'll actually wake up and know that next cycle it can go. So, that's all the wake-up. Any question? So, with register renaming, what does speculative execution now look like? Commit is much simpler because there is no need to transfer values from ROV to register file. In fact, no computed value is stored in ROV. Now, the ROV only stores a few state reads about the instruction and just maintains the order. Branches update predictors, branch target buffers, and return under stacks when they commit. Killed instructions just drain out. So, these are the instructions that are the wrong path, later discovered because of misprediction. So, they just get marked as killed, and ROV will just remove them from the processor. Also, stores write to memory at this time. Store queue or speculative store buffer holds a value. So, remember that we say that we distribute the issue queue into household reads. So, memory subsystem will get two issue queues. One is a load queue, other one is a store queue. So, the load instructions will go into the load queue, store instruction will go into the store queue. And the store queue will also have the value that it needs to store. So, when the store comes to the head of the ROV, the value will be moved from the store queue to memory. And finally, the ROV entries recycle. So, that it can now be used. And remember that the issue queue entries are recycled when the instruction issues. So, they are recycled much earlier than ROV entries. So, ROV entries held if you go back to the pipeline. So, ROV entry is allocated in the allocate pipe stage. And it remains held until the instruction moves to this stage. That's a pretty long time actually. Whereas an issue queue entry is allocated here in the allocate stage, and it gets freed as soon as it is used. Because there is no need for this issue queue entry anymore. Instruction is the only issue. So, issue queue entries actually remain held for a shorter period, whereas ROV entries are held for a very long period. So, what is the implication of that? Can you refer anything of the relative sizes of these 2 queues? ROV entries remain occupied for a longer period of time. And the issue queue entries remain occupied for a shorter period of time. So, which one should be bigger? ROV or the issue queue? ROV. ROV, that's pretty obvious. Branch misperception recovery needs to restore the register map. So, we have talked about this. This is a restaurant check point, the same thing particular. Whenever a branch is renamed, you take a check point of the map table. And if it is mispermitted, you just restore the map table. In addition to marking all the instructions were all by the scale. So, these are these instructions. Branches were going through renaming check point, the register map. Remember that these are not the values. These are only the map that is check pointed. So, here for example, when this branch instruction shows up, when it is renamed, it will only check point the map. Map meaning that it remembers that at this point of time, R19 was holding the map P45. R27 was holding P19 and so on and so forth. The value of P45 is not check pointed. Value of P45 can be whatever. So, we will soon argue why it is correct. Because it is not very obvious that we are not check pointing the value of P45. We are only check pointing the map that R19 corresponds to P45. So, could it be that some instruction actually updates P45 in a wrong way? The only observation here to make is why it is correct is that any instruction that comes, let us suppose that this branch was actually mispermitted. Any instruction that comes after the branch will not be allocated P45. It will be allocated to some other register. So, P45 can only be updated by this instruction. There cannot be anything else updating to P45. So, you do not need to check point the values. You only need to check point the values. So, again of course, we are continuously making implicit assumption that there is an algorithm which recycles registers in the same way. We will come to that soon. So, this one, the implication of this is that this one also talked about limits the number of outstanding branches. Because depending on how many check points you can echo more. If your processor can echo more than 100 check points, then your processor should be able to support 100 unresolved outstanding branches in point. Usually the number is much smaller than 100. Few tens of. Any question? Okay. So, the last point. How do you recycle the registers? Any solution? When should I? Okay. Let us go back to that. So, when should I free P15? When can another instruction use P15? When add-I has finished. Do I know that there is no instruction in future that we will be needing P15? There is no instruction writing to R4. No. Why? There is no instruction writing to R4. Sorry, say it. There is no instruction writing to R4. Do I have any such situation here? Okay. I do not have any common target here. Okay. So, you are saying that if there is an instruction which writes to R4. When? So, an instruction now has several, it is not really a point in it, right? It spans over a certain cycles. So, it is fetched. How do you do that? Instruction reaches. So, your instruction which writes to R4. Okay. Okay. So, essentially what he is saying is that let us suppose an instruction here writes to R4. All right. So, at that time R4 will be given a new map which is some register. Okay. Whatever that register is free. Whichever register is free at that point. And he is saying that when this instruction finally commits, I am guaranteed that P15 can be recycled. Which makes sense. Because from now on R4 has a new committed name. Okay. Right. Whatever was assigned here. So, R4 to P15 map now must expire. Okay. And I should be able to reuse P15 for some other register. Makes sense? Does everybody see that it is a conservative policy? I could have done better. Why? Because R4 has not used for a long while. Uh-huh. We can just expire this P15. We can use P15 for other registers. Right. So, do you see any difficulty over that? You are right. Yes. That is such an assumption. Why it is conservative? Do you see how to do that? Let me ask this question. I really cannot see the future. That is a problem. So, what do I need to determine? I need to determine if beyond a certain instruction. P15 is dead. There won't be any instruction meeting P15. That is all I need to determine. If I had a way to determine that, I could have done that. Okay. Right. Yeah. So, there are research papers which are looked at this problem. You can actually design predictors which can predict last touch to a certain register. That is actually. Sorry. Is it a standard information? Starting from point, you can follow different control paths. Right. And on different control paths, the register may become better different points. Yeah. You can remember the whole thing. On this path, the register becomes dead here. On this path, yeah. Of course. If there are enough storage, you can remember the whole thing actually. Yes. So, what instruction wake up the other instructions? Yes. So, we can type this G. What are instruction and getting wake up? Okay. All right. So, whenever all the instructions are being complicated for wake up instruction, then it is safer to. No. Does everybody see? So, what he is suggesting is that when this instruction issues, it will broadcast P15. So, all the instructions waiting in the issue queue will compare and you know what the instructions waiting for P15. And when all of them actually have committed, they can. How do you know? There will not be any further need for P15. It is not a wake up. There will be some instruction which is not a fetch structure which may require R4. Okay. So, yeah. So, as such, it is not an easy problem. Okay. So, what the processor actually do, what he has suggested. We wait until R4 is over it. And that instruction when commits, I know that the new map has been committed. So, I can now free P15. Okay. Now, the easy way to do that. So, how do you really implement it? That is how the question is. And the difficulty is that when this instruction commits, you cannot really say that, well, I look up the map table and find out what R4 maps to and I will free that register. That would be wrong. Okay. Because R4 now points to some totally different register. Because by the time this instruction commits, there may be many more instructions in the pipeline which already have over it in R4. Okay. So, how do you really free P15? How do you find out that P15 is the one to be freed when this instruction finally commits that uses R4. That overrides R4. Yes. Exactly. So, you remember in the ROB. So, when you rename this instruction, when you assign R4 a new map, you look up the table there and find that, oh, R4 now maps to P15 at this point. You just remember P15 in your ROB engine. Okay. And when you finally commit, what P15 has to be. Okay. So, that's why register recycling algorithm. So, now it should tell you why I don't need to checkpoint values for branches. Okay. Because there is no way P45 is going to be freed. Okay. And when we reassign before this branch commits, because any instruction that overrides P45 will have to come later. Okay. And it cannot commit. Okay. So, yeah. So, if the renumber runs out of physical registers, the pipeline stalls until at least one register is available. So, physical registers must be recycled. When is it safe to free a physical register? We have just discussed. So, that's the interesting question actually. So, think about this instruction. This one. So, here R2L gets mapped to P59. Okay. And the pipeline continues moving. Eventually, you figure out that this branch was mis predicted. Which means, this instruction should not have been fetched actually. So, now what do we do with P59? Why does P59 get fetched? It will be now. Right. Does everybody see that? As soon as this instruction comes to the head of the ROV in the kill state of course, I can free P59 immediately, because it's actually a non-committed map. Okay. So, there is no problem in free P59 and using it.  I can ignore it completely. I can ignore it. I can override it. So, more physical registers means more implied instructions. That should be now clear actually. But as soon as I run out of registers, my pipeline has to stop. Okay. So, if I have more registers, I can keep on renaming registers and keep on moving my pipeline. Okay. Right. And that also opens up possibility of more parallelism. So, number of registers have a great connection with how much ILP you can expose. Okay. But cannot make the register file very big because there are downsides. It takes time to access as it gets bigger. Because there is a thumb rule that you have to remember that is smaller is faster. And usually both these structures are slower. Okay. So, as you make it bigger and bigger, it's going to be slower and slower. Okay. So, you start using CPI in some other case. Okay. And also it burns power. It's very important. Large structures usually very energy efficient. What is that? Is there a relationship between ROB sign and register file size? Okay. So, today register file size means the number of register registers. What do you think? Should there be or can there be size? Actually maximum is less than equal to this register. Right. What is less than equal to? The ROB size is less than equal to the register for registers. What? Mapping of all these registers. Mapping of all these register registers. So, at max we can map all these register registers. When we are using all these registers, we have a mapping for all these registers. So, you are saying ROB size is less than equal to physical register size. Right. Right. All the distributions are same. Right. Right. Okay. So, whatever the size of this register file size is. Yes. So, that many register registers are same. Right. Okay. There is one more entry. Right. So, what is the same destination register? There is no cross-money mapping in the register. If all the instructions have the same destination register. Yes. Then I will be actually reciting the register. Right. What do we do? At the time of commit. Yes. You are not committed. The worst case would actually be that. Okay. All right. Fine. So, what are you suggesting? So, less than equal to? What is this? So, you are saying that? You are right. So, you are saying that as many physical registers I have. I could. I should be able to rename those many instructions. So, which way is the equality? What makes sense? Sorry. There is an equal to. There is an equal to. Yes. Because if I have a bigger ROB. Some of the slots will remain empty. All right. I cannot rename these. In the worst case. Can I tighten this a little bit?  Sorry. n minus 1 is what? What is n minus 1? This one we have already. So, you are saying ROB size cannot be bigger than n minus 1. Why? It is independent of this size, isn't it? I have n logical registers. Yes. Two times. How do you add that? You are using two names for single register. If a register is using R4. So, add is using R4 as a source. And then a load instruction is using R4 as a register. So, we have to use two names for that. Right. So, we can't.  It will be three, four names. Because register will not be free until that is completed. You don't know when it is going to be. But then after the load instruction, you would use the same physical register. No. So, you are saying that there are two instructions with the same target. No. No. Okay. Sorry. Yes. So, one instruction is using say one as source after a source. So, it has one mapping. They are using one name for that. And one is using it as a destination. No. Which comes first? The destination one is after the source. So, we have to use second name for this. Right. Okay. And we should require more than these two names. What if you can have another instruction that uses the same register as target? We can feed the only one that commits. You don't know what to do. By then, you may have 20 more in condition of the same register. So, if I add the ROB size. ROB size should be? ROB size should be? ROB size should be. Okay. Okay. Another name? Why? I mean I have raised my arm. What's wrong with that? I mean I have an arm of your own instruction. You find it. No. No. What I'm saying is that the minimum number of physical registers occupying is going to be N at any point. Register of my size should be greater than N. Okay. So, we have that we have already discussed right. That our size should be greater than equal to N plus 1. So, I have already n physical registers occupied, now I start fetching installments, can I just say like this, in a always occupied, whatever I have left with only that much I can allocate in the worst case, of course eventually they will get freed, but I do not know when they will get freed. So, I should not have an arbitrary size bigger than this, arbitrary size should


Wel, rydyn ni'n gwybod i'r ffordd yw'r lefwyr cymdeithasol, sy'n gweithio i'r ffordd o'r ddweud ym Mhwygratio a Dysgrifolau, ymlaen i'r ddweud o'r ddweud o antropoligau a'r ddweud o'r ddweud. Dwi'n ddweud i'r colleg John Parker ar hyn o gwneud hynny, ac rydyn ni'n gweithio i'r ddweud o'r ddweud i'r ddweud, rydyn ni'n gweithio i'r ddweud o'r ddweud o'r 2007. Rydy'n gweld o'r ddweud i'w gweithio, a rydyn ni'n ei chael ei fod o facilities byddys goingonol, ac mae'n gwneud i'ch ddechrau pe ysgolio. Rydyn ni'n gweithio i'r ddweud i'w gweithio. Rydyn ni'n gweithio i'w gweithio. Rydyn ni'n gweithio i'w ddweud i'w gweithio.  Which range from jazz to anthropological theory to the connection between history and anthropology. Where obviously that's one of the reasons he's doing this particular lecture. So if we look for key themes in his work we'll probably find religion's spirituality, its interplay with science, ideas of hybridity and also constructions of history. I have to say it's been a real pleasure to go back and remind myself of some of his earlier work. mae'r cyflawni'r cyflawni'n gweithio. Mae'r rhaid i'r ffwrdd yn gwneud o'r ffwrdd ystafell sy'n gweithio'r ffwrdd yw'r ffwrdd afro-afro-afro-fwrdd sy'n gweithio hirscwyd, Sydney Mint, CLR James a'r sannirau Llywodraeth, Llywodraeth Gwladysgwyr, a George Clinton. Mae'r ffwrdd yn gwneud ymddiad. Mae'r ffwrdd yn gwneud o'r ffwrdd afro-Cuban a mae'n gweithio'n gweithio'r ffwrdd o'r dialogue a'r ffordd o'r ideaeth afro-americanaeth o'r concept of African Atlantic religions sydd yn gwneud o'r ideaeth atlantic world. Felly, yn y traddogieth Sydney Mint bod yna'r Llywodraeth yn gyffredig sy'n gyffredig o'r llun yna'r 2007. Mae'n cael eu gweithio'r rhannu i'r hynny yn gwneud o'r hystafell ac yn y cwm yn gweld y gweithio cyfnodol yn gweithio'r gwybod, er bydd yn gweithio'r cyfrifiadau yn ddod yn amser yn ei wneud. Y cwm yn y cwm, a'r cwm yn yr ysgolwyddoedd ac syniadol, pan yw'r amser yn ystodio'r cyfrifiadau historiogol yn Cybus, ac mae'n amser yn y gwybod yw mae'r cyfrifiadau yn ei rhoi am ddegwyd ar gyfer nodio am y traddysgafafaniaeth a'r cyfrifiadau ac mae'n dod yn y tarod of a historical construction of Cuban and Atlantic modernity, which is mutually constituted. So he provides us with a study of Cuban religions and social science in relation to civil and state societies. And what that does is really to illustrate the emergence of modernity and its constitutive hybrid forms. And I would include in that its epistemologies. So it's a very powerful argument of how Afro-Cuban religions are hybrid products of modernity. And, you know, Stefan's, he's edited many volumes as well. But I think slave cultures and the cultures of slavery being one of, I think, one of the most important, which signal the shift really to looking at the lives of slaves at ground level in their relationships with their masters. And that really sort of signaled a new way of looking at the history of slavery, which is quite significant. But I think what Stefan's work does is to go beyond that balancing act. He brings to the fore the subjectivities of individuals. We don't always fit into the neat categories with which we understand wider historical questions. Quite often the subjectivities are sort of an uncomfortable fit. They can't easily be contained. They're neither pure victims nor undiluted heroes. So the other important thing, just to sort of round up now, I think that Stefan does is to raise questions of how we look at the debates around an African past and how it relates to the present. Because he uses his wonderful example of the fly whisk. And what he points to is that if things look similar, if they look similar in the present moment and the past, we then think, well, they must be the same. And what that does is then help us frame a narrative in a certain way that gives a sort of chronological explanation of how that came to be. But we have to ask ourselves, is it quite so simple? He raises tensions about ideas of continuity and discontinuity, which have dominated much recent writing on slavery. And I think what that does is to reveal a wider anxiety about a commitment to or a betrayal of origins, where origins really also help shape these ideas of subjectivity. So the questions of, did slavery destroy the vestiges of African culture which survived the Middle Passage? Or were there relations of continuity which illustrate resilience, resistance, and survival? That always sort of seems to be the question. The trouble was, as Stefan points out, these concepts required relating an African past to a new world present. And the search for an African essence rests on the construction of an African other who is also understood as authentic. So I think what he very rightly suggests is that that conjures up a picture of our desire to consume the other, if you like, necessitating a sort of separation between subject and object. And also this translation of space into time in order to construct a suitable African past, one we think is sort of appropriate for our story, if you like. So Stefan's work suggests that in place of this past and authentic subjectivity is what we need to do is put to the fore ideas of hybrid Atlantic space, containing things which belong to the modern world. So in this particular form, neither Africa nor slavery is placed on the past, but is part of a much more interesting and emergent present. So instead, we have a sort of contemporaneous African Atlantic space instead of a past and a present. So I was thinking about all this, and my thoughts turned back to Kit. And your comments about Django Unchained. Because I thought metaphorically, we in fact could see Stefan riding alongside his spectral African Atlantic subjects, a bit like in Django. And what he's doing is helping give voice to very different kinds of subjectivities, ones not constrained by normalized ways of seeing. He too is accompanying his subjects on a journey which seeks to overturn the tropes, which normally binds us to a certain way of understanding African American history. And that is surely very similar to what to Dr. King Shultz was doing in Django Unchained. So thank you, Kit. So I'd like to introduce Stefan. One word, actually, I didn't realize this week, that quite a few of my colleagues misread your abstract. So if you've come here today thinking you're going to hear a paper about pornography and its relationship to the spirit world, I'm afraid you're going to be disappointed. The word is phonography. Oh, that's an interesting paper. Yes, yes. So I give you, Stefan, the genre of North Thamont Avenue, the Wizard of Manlow Park, and the dialectics of insonement, an episode in the history of an acoustic mask. Stefan. Well, thank you very much, Paro, for beautifully nuanced and actually, to me, an introduction that I find now hard to live up to, but I'll try my best. And well, actually, secondly, of course, thanks to Kit for making this all happen. And everybody else involved. And thanks for coming. So let me start with a few apologies, because my talk today is based on a very long essay of which I can really only share bits and pieces with you today. I also realized that since few of you will likely have more than a faint acquaintance with the ethnographic subject of my talk, which is a male esoteric sodality known in Cuba as Abacoa, I realized that a bit more mise en scène might be called for than I can actually provide you with here, but I'd be glad to answer any questions that you might have after the talk. I started working on matters often lost. And I'm not quite sure rightly so by the term Afro-Cuban religion in the mid-1980s. And I've actually just finished a book, a little bit of shameless self-promotion, which is going to be out in probably June or July. And that book tries to question what it might mean to do something like study Afro-Cuban religion with all three terms in quotation marks. Now, I did my first ethnographic field work in Miami among practitioners of regla de orcia, more popularly known as Santaria, and started to work in Cuba itself in 1991 that is just about at the time when the really bad times of what the government declared a special period in times of peace were beginning to kick in. There are several African-derived ritual traditions in Cuba today, and most of them, conveniently for me, happened to converge in Havana. And there are historical reasons for that. All of them have been traced to some, oftentimes highly specific African antecedents. But that's not what I'm particularly interested in, and I think Paro said it better than I could right now. Personally, I think that origins are interesting. But really only if one cares about the kind of cultural and political work performed by them within historically and ethnographically specifiable social settings, not as an end in itself. Now, the question of what kind of work they do, that's certainly something that I'm very interested in, but it's not what I will talk about much today. So instead, let me turn to the topic that I would like to elaborate on. I began to work on these matters in the late 1990s, and it concerns, as I already said, a male esoteric sodality known as abaqua. And here, and almost misspoke, a note of clarification is immediately in order, because abaqua is often written about as a secret society, and an African one at that. It is nothing of the sort. One would have to qualify this, but what I would like to say is that it is a male initiatory cult that revolves around a mystery whose secrets only members and not even all of them are privy to. In other words, there is no secrecy about membership in the town of Regla, formerly industrial part of the larger Havana harbour complex on the eastern side of the Bay of Havana. In that town of Regla, where I do my fieldwork, everybody knows who is a member of abaquan who is not. No mystery here. Little boys playfully enact fake versions of its ritual, and many of them aspire to become what is called an acobio, that is brother in their late teens. No mystery either about the Andrews centrism. To be sure, only ombudys and real ombudys, not effeminados, can become acobios. But does that exclude women? Well, yes and no. As in practically all ethnographically known cases of male esotericism, women know perfectly well what the guys are up to when they do their thing. I mean, I repeatedly learned just that such as when sitting with men who told me stuff so esoteric that it made their flesh crawl, all the while female partners or daughters were walking through the crammed quarters, serving as coffee, borrowing our cigarette lighter, and so on and so forth. So, you know, that question needs qualification, that issue needs qualification, and final qualification a few words at least about the, you know, African derivation of abaqua. Let me get a sip of water here. Both oral history and documentary evidence indicate that the first chapter of abaqua was founded in regla in 1836 by members of a voluntary association of Africans, based on some idea of ethnic commonality, legally condoned by the Spanish colonial state, and known as the Carildo de los Carabalí, Bricamo apapa efi. And here you might want to know that dozens and dozens of such Carildos de Nacion voluntary associations of Africans exist in Havana at the time. Though it took scholars until well into the 20th century to figure it out, the very terms Carabalí and efi in the name of this particular Carildo, nowadays tend to be understood as reference to the ethic of old Calabar in the cross river region on the borders between Nigeria and the Cameroons. This onomastic connection and other formal similarities have led to by no means unreasonable speculations about the relationship between Cuba and abaqua and similar sorts of male sodalities, variously known in the cross river region on the names such as ekepe or nebe. Like these African counterparts, abaqua has eminently law-giving functions, and its career in Cuba can indeed be explained by them to a certain degree. For just as this type of association rose to prominence in old Calabar by organizing the slave and later palm oil trade, so was it spread in Cuba, immediately connected to its political and economic functions. Beginning in the 1840s, rapidly multiplying chapters of abaqua known as potensias began to maneuver their title holders into positions as gatekeepers for access to labour at the dockside, in tobacco factories, slaughterhouses, the centralized market and other economic complexes. By the 1930s, they were practically in control of all dockside labour, directly contracting for stevedore and warehousing jobs with international shipping lines, sometimes collaborating with labour unions, sometimes breaking their strikes, and often clashing quite violently with the police. Now for this and other reasons, not a few scholars have argued that we are dealing here with an Atlantically Transplanted Diasporic version of Ekbe. Precisely, this logic has sent one of them, the American art historian Ivor Miller, on a historical mission to reunite members of abaqua, Cuban members of abaqua, exiled in the United States with their epic brethren in Africa. Now I have some sympathy with Miller's project, but apart from the fact that few of the Ocobius that I know in Cuba seem to care much about such homecomings, the project itself strikes me as already mistaken on historical grounds. For not only did the supposedly African version of abaqua arise near simultaneously with its supposed new world offshoot, rather the Cuban version soon after returned to Africa when members, Cuban members of the association who were deported during Cuba's two 19th century wars of independence, carried the association to Spanish penal colonies such as Ciuta, but also Fernando Poe, nowadays Bioco, from where, as the Spanish ethnomusicologist Israela de Aransadi has recently shown, Cuban ritual forms diffused back to their supposed places of origins in present-day Nigeria. But let me now bring these preliminaries to an end and show you a few pictures. And here I must say this is the second time in my life that I've given a PowerPoint presentation, so bear with me. So let me show you a few pictures before I launch into the subject proper. And in case you would like to know about abaqua's current economic activities, I'll be glad to answer such questions at the end of the talk. So let me see how it goes. This is where, according to oral history and some archival documentation, newly landed slaves in that cavildo de los caravalli bericamo apapa efi implanted the mystery of equae in Cuban soil, that's the embarcadero of regla in 1836. Here's another view, that's the old embankment, and there's a hydroelectric plant on the side where a massive slave market used to be barracks and all that. Now this is a plaque which, in 1997, members of abaqua managed to actually get the government to install for them at that place, reads to the Africans who, in 1836, founded in this town the secret society of abaqua. Here you see members of the bourreau provinciale de abaqua of regla, local dignitaries in the society, most of them higher title holders, celebrating that precise anniversary on January 6, 1836, in, I think, that was probably 1999. But let me now get into the substance of the paper. It has quite a long history actually, the paper began sometime in the 1990s when I was working in Fernando Ortiz, the preeminent 20th century Cuban social scientist, really a polymath in many ways. When I was working in Ortiz's vast and sprawling archive in Havana's Instituto de Literatura Linguistica, because there I found a clipping from a Cuban newspaper summarizing a report in a 1908 issue of the Philadelphia North American concerning two black Cuban brothers named Leal who had set up a kind of storefront operation on Philadelphia's North Fairmount Avenue that seemed to combine Edisonian sound technology with what Don Fernando, I think rightly, surmised where elements of the ritual repertoire of abaqua. I think it was in the New York public library that I eventually tracked down what in fact turned out a quite substantial article on the Leals and their curious sound system technology by which they broadcast spirit voices from their temple of the ancient grace onto North Fairmount Avenue in Philadelphia. Much like Fernando Ortiz, who stuck the clipping into a folder entitled Negros Nyanigus, which is now a term for abaqua, which contemporary Korea Nyanig Abaqua that is men born over the drum skin regard as derogatory. But much like Ortiz, who filed this away under category that referred to abaqua, I too filed those Xeroxes of the Philadelphia North American away. At the time, I had just begun my own research on abaqua and the Xeroxes literally sat in my filing cabinet for more than a decade. I always wanted to do something with them, but I now realized that it was really only on the background of years of doing intermittent ethnographic work on abaqua in regla that I was able to see the theoretical challenge posed by the simple snippet of information on the rather peculiar practices of two Afro-Cuban migrants in Philadelphia more than 100 years ago. But let me give you a taste of the repertoire to show you what I mean. Here's what Timotheo Leal, who calls himself a yamba, the leader, that is y yamba, which is nowadays the highest title in abaqua. Here's what Leal is said to have told the journalist. I talk to the spirits and they talk with me. See my echo? See my echo? Now Leal seems to be quite proud of his echo and the reporter seems impressed as well. Here's the description he gives. It starts in the middle of the room in a sort of pagoda filled with water. Things that look like painted spools float around gaily. A tiny bell is suspended from the roof of the pagoda and when the spirits happen to be around, they always notify a yamba Leal by ringing this bell. From under the water, a speaking tube stretches across the room to a converter.  Leading into the converter from the western end of the room is another speaking tube. Still another tube finds its way into the converter from a kettle drum in the east. This kettle drum is made of a china wash bowl covered with skin. A final tube is carried out into Fairmount Avenue. This has a megaphone exit and it is from this megaphone that the people in the neighborhood get notice that the spirits are busy. Now, what in the world is that? And why call it the echo? I must confess that it took me forever to figure it out. But apart from the fact that the article features dozens of other pointers towards Abacoir, plume staff, roosters, jute masks, drums, et cetera, it really only dawned upon me when I reread what a woman present in the temple had to say about the phonetic qualities of what she and Leal called the echo. Do the spirits really talk? asks the journalist. Why? answers she. I have been in there alone and the drums started beating on their own accord and the echo made a noise like this. Woo, woo, woo! And then I got away. At this point, the scales fell from my eyes. The journalist had simply misheard. Leal and the woman weren't talking about an echo at all. They were talking about el eque which is a super esoteric friction drum at the center of Abacoir ritual which are known as barocos o plantis. And guess what? It sounds like mm, mm, mm, mm. Or if you like woo, woo. And so to, you know, to write rough shot over my own argument, what it does is to sacralize everything within its sonic reach. You have to have heard it at an Abacoir ritual to understand what exactly a yamba leal meant when he proudly showed the journalist his ingenious combination of early analog sound technology with the much older acoustic mask known to contemporary ecoreaniene Abacoir as el eque. Now let me postpone explaining what I mean by acoustic mask and point to the irony that the woman says to have fled the scene after hearing eque's mysterious voice. For that's precisely what the mythical woman, Sican, failed to do when she first heard the voice of Tanze, an ancestral presence in the shape of a fish that she accidentally scooped up in her calabash when drawing water at the mythical embankment of Usagare from the River Oldan that bisects the territory of Becura Mendo in the Efo region of Abacoir's mythical homeland in Yenyson. And here you see the whole scene about which I will now be talking. Here comes the story. It is the end of a starry night. In Kiko, the rooster sings on top of the hill where Equinyon, the hunter, waits for a spray, bow, and arrow poised for the kill. A caiman initially blocks Sican's path to the river, but the man, soon to experience transformation into the ireme, which is a spirit from the bush, basically, into the ireme Eribangandau, clears her way with a ritual brush. She bows down, scoops up a calabash of water, but when she hoists it on her head, a tremendous roar issues forth from the container. It is Owon Tanze, a numynous presence in the shape of a fish who speaks to her in his otherworldly voice. Having been the first to hear Tanze's awesome bloggers, Sican is variously said to have confided her terror to her father Mokongo or her husband Isonecwe. Either or both, betray her to the supreme chief Iamba and the sorcerer Nassako, who had been tracing Tanze's movements and vocalizations, Cama Ororo, as they say, speaking in the center, in the lagoon for days. Equinon, whose name is glossed as slave to Eque, is now ordered to kill her. However, even before Sican meets her violent end, Tanze is dead as well. His voice has fallen silent. Horrified, Nassako Iamba and the other Obonnes, founding figures soon to become titles, try to revive and recuperate its awesome law-giving sonic capacities. What ensues is a strangely phonocentric version of the search for a male social contract. Sican is seated on three stones, awaiting her immolation when she begins to menstruate, thus foreshadowing the feeding of the three-footed friction drum, Eleque, around which the ritual technos enabling men to cause other men to be born over the drum skin will soon congeal. Following Sican's execution, Nassako ffuses her skin to that of Tanze, to no avail. He and the other Obonnes will sacrifice the snake, Nyangabion, that had coiled itself around the palm tree that night. You'll see the snake around the palm tree. They'll sacrifice Erombe, the Congo slave, captured by the sound of the voice. They'll sacrifice Eronne, the ram, Yebengoo, the tiger. Nothing works. Much blood if you shed in vain in their frantic experiments. It is only when they resort to sacrifice in Bori, the goat, that El Parche, the drum skin, eventually takes shape. And once fused to Ocanco, the hollowed-out trunk of the sabre tree becomes operative, and this is a key term as namberee, the flesh of the voice. Let me show you this. You know, this is like a, yeah, now we've got photos of meeting houses. You know what a sabre looks like, I'm sure. What results is a technology capable of transmitting lavos, the voice, across time materializing its sound onward from baroco ceremony to baroco other ceremony. And this is the moment from whence, as contemporary Cuban Obonec was envisioned it, an unbroken chain of what they call transmissions, transmissiones of the voice, links the inner sanctum, the quarto fam bar, of their temples in the ritual exterior spaces called Isaroco, which are often times simple alleyways, to the primal embankments of Usagari, where the sound approximated by the phrase El Uyo, that's how they would call it, was first materialized in, and mediated by an esoteric biotechnological device, El Ekwe. And here, you can show you some of the temples, so you can see, some of them are quite substantial. And here, finally, you see the sabre. Oh, we're not getting the pictures. Yeah, yeah. So here we are getting the temples. Here's the sabre tree. And right, so we'll stop here. But Ekwe itself is only an agent within a larger network that forms as soon as the original 13 title holders of the Tierra Efo now turned into ancestral personae with names designating their future offices, plasasas, transact the secret of the voice across the river to a group of men soon to constitute the first potencia of the chapter of the Tierra Efi, and these are two, I mean, there are three main branches. One is Efo, Efi, and Oru. So reviving the voice is only the first step in its reproduction. It now begins to spread in space and time. And here we can now omit much of the mythological detail and switch to the sequence in forming contemporary barocos in all of their multi-mediated splendor. Hours of pre-dawn work go into the fabricacion, the production or perhaps better assembly of the conditions under which Ekwe's voice can be transferred to a medium that will carry it forward in time space by enabling men born over the drum skin to perform assisted reproduction in bringing other such men into being. Even before midnight, the temple holders will assemble in the sanctum of the temple to conduct a rigorous schedule of ritual work. Nassaco begins to concoct lawemba and the basic ingredients of la mokuba. The former is a cleansing fluid, the latter a liquid conducer of Ekwe's extra sonic powers. Now the title holder named Empego will begin to write authorizing glyphs with yellow chalk on all major ritual implements as well as on the ground leading from the innermost sanctum towards the door of the temple, charting the path the voice will travel hours from then. In all of this, the physical temple is only a space through which Ekwe maintains its relationship to the world. The voice itself lives in the waters from where it has to be summoned and to which it eventually returns. To this end, a potencia activates a ritual infrastructure composed of an elaborate network of human, man-made and natural agents. A sacramental machinery designed to conduct or perhaps better, transduce a numynous energy into a variety of worldly forms available to the human sensorium. The altar's drums, staff, insignia, the hieroglyphic writing, even its ritual personnel, are mediators that need to be brought to a vanishing point of immediation that is reached when the plasas have once more become the ancestral presences who bring about the sounding of Ekwe's voice. Yn y bwya time, I mean, this of course circumscribes a very interesting vision of history in the sense. Now, once the fabrication nears its completion after hours of performing esoterical ritual works, obelas, Nasa Coel will trace a line of gunpowder along the elaborate diagrammatic phirma glyff that will mark the path for Ekwe to once more emerge and sonically transform the world within its acoustic range for those at least capable of heeding its call. By then, Ekwe'nion will step out into the first light of daybreak announcing the impending sonic incarnation to the profane world. Hei, hei, bariwa, ben kamma, meaning something like attention, admiration, it or I will speak now. So begins the lengthy chant he entones before Nasa Coel lights the gunpowder and the door of the sanctuary flings open in an explosive visual and auditory blast. What emerges from the temple's door is the first stage of la procession, the major blasa's title holders followed by a full drum orchestra guided by the irimi, Eri Bangando, who once more clears the path, and they go out in search of the voice. Only when they return will Iyamba, who has stayed behind in a corner of the fambas occluded by a curtain, begin to apply his fingers moistened with drops of mokuba to the yin, a plun piece of bamboo, poised on the resonant surface of a small, three-footed friction drum that is the source of Ekwe's vocalisation. Here you can actually see what that looks like. I mean, this should never be photographed, of course, but I didn't take them, so I can show you that. But just like the procession, that ritual march, is a mere effect of an as-of-yet-unrevealed cause, so is Iyamba himself, or better perhaps, the human body that has become his office, a mere instrumentality. Blindfolded, he himself only hears, but does not see how the yin that stick in his hand induces the vibrations on the drum skin that activate Ekwe's voice. His fingers merely carry Ekwe's luminous energy over into the phenomenal, that is auditory world, where it will pass through and bring into being further such chains of transduction. From the moment it begins to resonate from within the temple, the drone of Ekwe's vocalisations notionally both affects and directs every single of the twists and turns of the exoteric part of the ritual, that unfolds in the potencia's public space over the next six to eight hours. It takes forever. What ensues is a synesthetic riot that involves elaborate conversations, as they call it, between Ekwe and La Musica, the drum orchestra, between the Ekwe and the Iremes, these masked dancers, and you'll see one of them shortly, who though mute themselves, will react to modulations in Ekwe's volume in timbre in a gestural language of their own. And finally, it interacts with the officiating title holders, who will judge from the sound emerging from the inner sanctum whether or not the ritual steps they just executed were pleasing to the voice or badly executed. Transmitted, in other words, to Nambeeri, the drone skin by the flesh of the voice by the motions of the yn in the yamba's hands, Ekwe's power shifts from a luminous to auditory to kinetic, and not just aesthetic, but really ethical modalities. In a baroco yansaw that involves the initiation and swearing in of new or one Ekwe's or plazas into an existing potencia, it is Ekwe who calls the Iremes eribangandó and you know, here we can see him. No, actually, who calls the Iremes aberisun, this is now, to deal a deadly blow to the sacrificial goat in Bori, and it initially does so by deceiving the Iremes. Attracted to the scene, you can see sort of another one, attracted to the scene of the ritual by the voice, aberisun shrinks back in horror as he hears Ekwe's command and beholds in Bori, whose body has received the same chalk markings as the candidates for initiation. And just as Ekwe's voice will gain urgency, every time aberisun recoils until he finally strikes in Bori down with that cudgel, so will Ekwe rejoice when the goat's skin, called Tsukubakariongo, will finally be presented to the waning stars in the early morning hours as the banner of the association. Here you see that, this is a good friend of mine, presenting, and on the side you see the candidates for initiations, and on the bottom you see remnants of these sacred glyphs, and you will notice that the heads and the arms and shoulders of the initiates are also marked by these sacred writings. Yeah, this is another, this is when you just, this is holding it up to the stars. Ekwe jubilates when the indisime candidates for initiation are led into the sacred chamber and it will give birth to Nu Ekorya Nene Abakwa soon after, when in the course of a series of esoteric procedures, the head of a new initiate is placed on top of another drum called Ceci Eribo, which is never struck, and which only moments ago supported the severed head of the sacrificial victim. But now, of course, is crowned with the powerful, powerfully vibrating presence of Ekwe herself, and I'll show you those. So here you see the Ceci Eribo. You may notice that all of it has references to sound. The guy is holding the head of a rooster in his teeth. He's actually holding it by the rooster's tongue so there's transmission of a voice going on here as well. This is enveloping the Ceci in the skin of the goat. Here you see the Ceci crowned by a poor in body's head. You may notice that there are also ritual markings on his, and here the candidates are entering back into the, these are the initiates carrying their various implements that they have to contribute back into the sacred chamber. And here you have an ireme, another photo approaching with a rooster, and doing just what you saw on the announcement, namely cleansing the author with the rooster. So Ekwe, in other words, has intentionality. It has sensory powers. It takes notice of its surroundings, and it is capable of expressing effect, all the while affecting ritual actors within its phonic reach, sacralising and directing their actions. It is, in some, a mask. Just not a visual one that subsumes the body of its wearer under its power, but an acoustic one who's sacralising capacities extend to all who know how to experience and heed its call. In this sense, the acoustic mask that is Ekwe is a complex assemblage of human and non-human agencies. And I think I'm cleaving rather close to the views of contemporary albacoir members when I qualify it as a biotechnology. One, that while capable of exerting powerful agency of its own, needs to enlist human actors not only to compose its material instrumentalities, but to transduce its mystical energy from the numerous to the phenomenal realm, thereby, of course, reproducing its own agency across secular space and time as well. But enough of that. Let me now return to 1908 and the world of analog sound technology that was dawning at the time. Remember the story of poor Sikhan? We might say, good thing that Philadelphia woman hit the road when she heard of Ekwe. But while all of this gave me a wonderful opportunity to write up my ethnographic data on albacoir ritual, I now need to shift gears and try to give you at least a thumbnail sketch of my larger argument. And if anybody wanted to read the larger paper, I'd be happy to share it. In a nutshell, there are two issues that I'm after. The first one is that the Leal Brothers, technologically enhanced echo, can, I think, be fruitfully analyzed as a site of what appears to have been a remarkable convergence between the phonic and auditory ideologies underwriting the mediation of the divine in albacoir, on the one hand, and the technologies of acoustic transmission across space and time, particularly telephony and phonography, that had begun to reconfigure western auditory worlds since the second half of the 19th century. Secondly, I try to argue in the paper that just as contemporary albacoirs, sacramental technologies of sound transmission, activating the disembodied voice of the mystery, generates numerous sound envelopes that defy the precisely those space-time coordinates in which the whole thing takes place, so did the rational technologies of sound propagation and acoustic disembodiment of the mundane human voice that began to flourish in the second half of the 19th century engender their own numinous penumbra and sacramental logics. A process nicely subsumed under the concept of a dialectic of insonament that I have borrowed from Jonathan Stern, in mind its splendid resonances with Horkheimer and Adorno. Now I really don't have the time to go into the latter part of my story today, but let me just note here that both Bell's invention of the telephone and Edison's invention of the phonograph involved episodes at least as strange and macabre as NASA calls tinkering with the blood and skins of sacrificial victims. In fact, Bell's first functioning sound recording device, the so-called ear phonograph, was composed of the surgically extracted middle ears of paupers who had died at Harvard Medical Center and were mounted on a microphone stand and then fitted with a stylus that transduced the sonic vibrations registered by an eardrum no longer connected to a human being into mechanical energy. Here you have the famous ear phonograph. Bell actually had an autologist's friend at Harvard and he supplied Bell with these inner ears and Bell took them in glycerine up to his summer vacation home in Maine and you can imagine. Anyway, it worked apparently. Edison's subsequent, and why shouldn't it have worked, of course, Edison's subsequent discovery of phonography has often been described as involving a similar logic of human sacrifice, this time not of the ears of cadaveric organ donors, but of his own blood. As the story goes, Edison was tinkering with the version of Bell's telephone. Holding a finger to the stylus attached to the diaphragm when the vibrations caused by his own voice made the stylus prick his finger and draw blood. Now the reason he had put his finger there in the first place was because Edison's own partial deafness forced him to analogize between different sensory modalities and their receptivity to sound waves as a form of energy. A 1913 advertisement quotes the Wizard of Menlo Park saying, and I quote, I hear through my teeth and through my skull.  Now there are photographs of Edison's personal disc phonograph with highly visible bite marks. Excellent evidence of the principle of acoustic transduction across several sensory modalities that lies at the core of modern analog sound technology. Needless to say, the uncanny nature of such merging of body and machine, wetware and hardware, into the transductive conduit of an absent presence, previously recorded sound, was not lost on Edison's contemporaries, many of whom experienced the awesome novelty of disembodied voices as both technological fascinans and necromantic tremendome. As Edison himself repeatedly wanted, the voices of the dead could now be heard on tap. Bells, I should add, Bell's assistant Watson was actually an ardent spiritist who thought that the spirits had actually invented the telephone and put it at his and Watson's disposal. But anyway, surrounded by, as we are nowadays, by things that speak to us, think of the cell phones in your pocket or chatbots, if you want to book a ticket anywhere, we have completely forgotten the fascination from antiquity in the Renaissance onward with speaking statues or other such makine. Just remember Descartes, Locques and Voltaires, obsession with speaking parrots and the limits of humanity. But while I cannot go into the fascinating history of late 19th and early 20th century analog audio technology, you will want to know that ghosts came rushing into bells and Edison's machines almost as soon as their existence became public knowledge. Contrary to Max Weber, there is a genuine acceleration of enchantment on the way in the second half of the 19th century. If it had taken a spiritist almost 30 years to incorporate photography into their repertoire of media for spirit manifestation, the spirits at the Heidsville wrappings in 1847 began to communicate in Morse code within less than a decade of Sam Morse's invention in nearby Rochester. Eagly, of course, availed themselves of the necromantic potential of telephony and phonography in so-called direct voice manifestations right from the start. After all, the very possibility of rationalizing the hearing of disembodied voices that these technologies seem to provide so much resonated with key concerns about transcendence and immediacy that had occupied Western thinkers since the time of Plato, Aristotle and St. Augustine that it is not surprising that record companies adorned their logos with recording angels or dogs listening to their dead master's voice. Or, on the other hand, it's also not surprising that ethnographers who introduced the phonograph to people whose, shall we say, ideologies encompass dreams, possession, transes, and vision quests as genuine forms of communication between the living and the dead, human and non-human agents. This introduction of the phonograph to those people rarely elicited more than responses of polite boredom. So perhaps it was in the Leal Brothers case who, of course, would not at all have been phased by the notion of a technology productive of a disembodied voice. That's, of course, what Abacoir ritual is all about, namely creating the conditions for transducing equest voice from one ontological domain to another. And contemporary Cuban Abacoir members go about this in a highly methodological fashion, methodical fashion which they themselves refer to as the process of fabrication and process de la fabrication. Again, I can't really go into ethnographic detail here, but let me note two issues that I personally find quite fascinating in that regard. The first is that el-eque is decidedly not just a drum, nor even just an object. In fact, as I already said, the term really refers to a complex biotechnological assemblage that includes human actors, animal substances, ritual implements and spirits that are mobilized in order to enable emanations of pure, timeless sonic presence. Second, it is equa itself who enlists humans as instrumentalities of its sonic manifestation, not the other way around. I mean this is quite scandal-y abbreviated and may sound rather cryptic and I'll be happy to talk about it some more afterwards, but if the mystery that is equa allows men born over the drum skin to give birth to other such men, then it does so in order to ensure its own reproduction over time. Remains, and I'm now coming to the end, one fundamental issue to be discussed if only in passing and it pertains to both Abacoir and the turn of the 20th century audio technologies I discussed at some more length in the paper. And it is perhaps best encompassed by the phrase high fidelity, which so obviously and really rather painfully speaks to the flaws in a western metaphysics of presence and so expresses a semiotic ideology that mourns the human predicament of having to rely on socially-rutanized forms of indexical mediation. The mandatory fidelity in the sense is all about the sadness of a world in which the copy invariably must indicate the absence of the original. Unless that is, then non-identity can be made subject to socially pervasive processes of forgetting. RCA's old image of faithful nipper listening to his master's voice emanating from a phonograph horn speaks to just this problem. As does, of course, the resurgence of, or arguably I should say, of analog vinyl records among contemporary audio files. But are our old scratchy Jimi Hendrix records really any closer to the events in the Electric Ladyland studios in the late 1960s than a digitally remastered CD bought over the internet and we really cannot agree with Friedrich Kittler on that score. I mean, sure we might say, but only if we buy into a specific type of sonic ideology. One that allows you the luxury of imagining the vanishing of the medium into the message. And that is all but a technological outcome. It is a thoroughly social one. The problem is, of course, germane to Abacoir just as well. It is one that the Leal Brothers would have faced as well. Electrifying what contemporary members of Abacoir call the mechanism of la transmision of the voice from its numinous habitat to the world of men, and here of course the gender pronoun is appropriate, by sticking phonograph tubes out of your window is one thing. Creating a sonic envelope that sacralises everything within its acoustic reach for those who actually know how to heed Equus' call is another thing altogether. Just like Bell and his assistant Watson really only knew what they had heard when they belatedly told each other what Bell had yelled over the first functioning telephone, Watson, come here, I need you. So even the best recording of Equus' voice might sound like nothing but a weird drone to all of us as we sit here. As far as I know, the Leal Brothers remarkable experiment, conceivable as it really only became within the structure of the conjuncture of two originally distinct sonic and auditory ideologies, that experiment eventually came to nothing. But what the scant record of it does seem to tell us is that the very technologies that seemed so awe-inspiring, even mystical to a European and American listeners, were hardly more than means to an already agreed upon end for early Cuban members of Abacoir. For them the mystery lay where it always had lain since enslaved Africans had founded the first chapter of Abacoir in 1836 to bridge their bodies to the sounding of the voice. It lay in Equus' own agency across time and space.  I mean it's like completely incomprehensible and then it filter out more and more and more of the noise and finally you get something that you can actually recognize as a human voice. But this kind of technological outcome is not determined by technology as such. It is also determined by the kind of, you know, sort of sonic ideology that we apply to acoustic, you know, emanations that we take as indexical of something that in a sense stands behind them. And this of course is where the two, you know, where Edison, where the wizard of Menlo Park actually met the Yamba of North Fairmount Avenue in a kind of a, as my colleague, Marshal Sons would have said, you know, peculiar structure of the conjuncture that unfolded in Philadelphia in 1908. Thanks.