فشرف بالشتغالي بالعلم ولا تبغي به ما عشت يدى بدلا وياله من شراف عظيمي الحمد لله رب العالمين له الحمد الحسن والسناء الجميل وأشد أن لا إله إلا الله وحده لا شريك له يقول الحق وهو يهدي السبيل وأشد أن سيدنا ونبينا محمد صلى الله عليه وعلى آله وأصحابه والتابعين لهم بإحسان إلى يوم الدين أما بعد إن شاء الله تعالى today we're going to be talking about أحكام rulings pertaining to praying on the chair this is one of the most common issues that people bring to me they ask me regarding what is the ruling the أحكام pertaining to praying on a chair and this has become a if i could say an epidemic the muslims are you rarely come to a masjid except you find one or two people praying on a chair and then when you observe those people who are praying you realize they don't follow the rulings pertaining to it and the أحكام that they need to come with or you sometimes find people who are able to pray standing up choose to pray sitting on a chair if you travel and you go on a plane you find the people praying sitting on the on the airplane on the chair instead of standing up and praying so this is something that needs to be properly understood أو else this may have a problem on the prayer my beloved brothers and sisters who are listening to me the scholars and the people of knowledge they gave a lot of importance to the matters of salah either talking about it or throwing a book regarding it and whatnot so don't take it lightly and think to yourself that this topic is a very light topic are you going to designate a whole lecture on this topic there are many more other important things to talk about كلا والله that's not the case because the صلاة is the greatest thing after the after the شهادتين after أشد الله إلهي الله and أشد أن محمد الرسول الله what comes is the صلاة so the way i plan بإذن الله الكريم to go through this topic is as follows i'm going to break it into three parts إن شاء الله وتعالى today إن شاء الله وتعالى sit on today's lecture بإذن الله الكريم first part is going to be مقدمة عامة general introductions which i will speak about قواعد and حكام which are very important for one to understand and this is not as a type of introduction you see so you're going to have an understanding before we go into the topic then إن شاء الله وتعالى the second part بإذن الله الكريم is going to be is going to be the body and the main topic at hand which is the حكم and the rulings pertaining to sitting on the chair and the last one إن شاء الله وتعالى is going to be a conclusion is going to be a conclusion bullet pointing everything we spoke about so you have a better understanding because sometimes i might go out and i might come but at the last point i'm going to give you point one point two point three point four so you are upon clarity إن شاء الله وتعالى so i'm going to start with the introduction right now بإذن الله الكريم as i had said right now the most important نظر بعد الشهادة إن شاء الله وتعالى إن شاء الله is a pillar in which a person's religion stands on and a person's islam does not exist if the prayer is not present and the prayer doesn't also exist so your islam does not exist without a prayer and your prayer doesn't also exist unless you come with prerequisites which are شروط and unless you come with the أركان the pillars and the واجبات and of course your prayer would exist but to also come with the سنان they're recommended الله سبحانه وتعالى he says in the Quran صورة المؤمنون آية one to آية two الله says success and prosperity is for the believers who are they الذين هم في صلاة المخاشعون those who find in their prayer خشور فلح المؤمنون prosperity is for the believers which ones الذين the ones الذين هم في صلاة المخاشعون the ones who find خشور in their prayer humility أصول الله تبارك وتعالى he says إن الصلاة كانت على المؤمنين كتابا موقوطة that the prayer is on the believers إن الصلاة كانت على المؤمنين and the prayer is to the believers كتابا موقوطة a designated time the salah has been made obligatory on the muslims at a particular time it has أوقات times you have to pray there's time for us time for sorry there's a time for us every every one of them it has a time also الله تبارك وتعالى he says in صورة التوبا آية 11 فإن تابوا if they repent وقاموا الصلاة and they establish the prayer واتوز زكاته and they give the زكات فإخوانكم في ديني they are your brothers in faith so the repentance is connected to what فإن تابوا if they repent وقاموا الصلاة and they establish the prayer واتوز زكاته and they give the زكات فإخوانكم في ديني then they are your brothers in faith so the ayah is telling us if they don't do that they are not our brothers in faith that is the مفهوم of the ayah and this is the ayah that the scholar has used that anyone who leaves the prayer is a disbeliever وقوله أصغر الله سبحانه وتعالى he says in صورة مريم آية 59 فخلف من بعدهم خلفوا خلفوا أضاع الصلاة والتبع الشهوات فسوف يلقون غية فخلف من بعدهم خلفوا أضاع الصلاة والتبع الشهوات فسوف يلقون غية after them came a people أضاع الصلاة they forsake the prayer والتبع الشهوات and they follow their desires so forsaking the prayer is a if you follow your desires if you forsake the prayer your person who's following his whims and his desires فسوف يلقون غية they're going to be thrown into what غية is معزم عباسر is what is a valley in جهنم وقوله أصغر الله تعالى he says in صورة المدثر آية 43 ما أعرفت باسر وكبار ما سلككم في سكر قالوا لم نكم من المصلين ولم نكم نطعم المسكين وكننا نخوب مع الخائضين وكننا نكذب بيوم الدين حتى أتانى اليقين حتى أتانى اليقين means until death came to us so what was it that brought them to the house fire قالوا لم نكم من المصلين we were not from those who used to pray أصوى الله تعالى تبارك وتعالى he says فويل للمصلين where be to those who pray which ones الذين هم عصلاة مساهون those who delay their prayer who come with their prayer deficient أصوى الإمام البخاري والمسلم they both narrated الناس صحيح من حديث عبدالله ابل عمر ده مسلم صلى الله عليه وسلم السلام بني الإسلام على خمس شهادة اللى إله إلا الله وأن محمد الرسول الله وإقام الصلاة وإتاء الزكاة وحج البيت وصوم رمضان حديث is collected in بخارية المسلم إذن the prophet tells us in this حديث that the religion is built upon what five pillars the first one of them is what شهادة اللى إله إلا الله that there is none worthy of worship except الله وأن محمد الرسول الله أن محمد is he's what he's messenger وإقام الصلاة أن استعمل شنوات prayer الإمام أحمد pay attention here الإمام أحمد أن أهل السنة أبدو تلميدي بلماد النسائي they narrated من حديث بريدة رضي الله تعالى عنه ده مسنج السد العهد اللى بيننا وبينهم الصلاة فمن تركها فقد كفر the covenant between us وبينهم and between them is the prayer and anyone who leaves it off فقد كفره he's a disbeliever are you with me what does it mean the covenant between us and them what do you guys understand from this yeah yeah what do you guys believe in the covenant yeah what did you guys suffer was it the covenant meant here means the prophet صلى الله عليه وسلم is talking about the the thing that gave them isma to demi والمال the reason why their blood is is sacred and protected it's because they're praying حتى وإن كان ظاهرة as for us you disbelievers are in a state of war and fight with us we're fighting with them so the thing that we give them a contract to them for is the prayer after the shahadateen when they come to the laela is the prayer are you there if they break this contract as they like they stop praying that they become so we you fight with them like we're fighting with the now brothers pay attention here this is a summary of a long discussion that we don't want to open but this is what this is what this حديث the messenger عليه الصلاة والسلام specifically mentions that the person who leaves the prayer is what the messenger said just a mere leaving he didn't condition it to be out of laziness or not it doesn't matter this condition of whether it's laziness or not the messenger left the unrestricted so it encompasses that it's in there and the قاعدة مقررة في أصول الفق the قاعدة which the علامة of أصول الفق agree upon themselves and they take on board which is what a دليل which is ظاهر apparent and it is واضح it's clear in in its approach we can't turn away from evidences which are clear cut for evidences which have احتمالات in are you with me the evidences that have come pertaining to the one who leaves the prayer are clear cut فمن تركها فقد كفر the evidences that those who say are you with me that it's not كفر unless the person leaves it out of جعود the evidences which they bring are not it has احتمال the possibilities are in there other meanings can be taken out of it so for you to go against اي دليل which is this straight and clear to the point for evidences which are what those evidences can take more than one phase is not right موصد the messenger صلى الله عليه وسلم يسلم حديث صحيح مسلم من حديث جابر ابن عبد الله رضي الله تعالى عنهما that the messenger said بين الرجولي وبين الكفري تركوا الصلاة these حديث are not they are صريح they are نص which is what بين الرجولي وبين الكفري بين اي من and disbelief is just to leave the messenger says to leave the prayer then what we see is the sahaba is understanding how did they understand it عبد الله يبن الشقيق ودريساين كان الصحابة ورسولي الله صلى الله عليه وسلم عبد الله يبن الشقيق said the companions of the messenger they never used to see disbelief for any action a person leaves off other than prayer يا اجمع الصحابة the sahaba is unanimously agreed upon if anybody left the prayer he's a what so the importance of the prayer and where it stands in our religion is not a very light issue the evidences have come in multitude narrations and evidences have come in multitude in the kitab and the sunnah and also eachماع consenses have come regarding على فضلي الصلاة the virtues of the prayer والترغيب في فعليها and urging and pushing the people to pray the salah وعلى خطر التهاوني بها and also the dangers and how serious it is if a person is careless about it والترغيب من تركيها so because the prayer has that importance as i said and your religion your islam is connected to this prayer without it you're not without it you are not what without it you're not a muslim when it comes to the people of the sunnah they say that the faith is a word and a work the faith is a word and a speech and it is an action the first thing they were referring to was the prayer that the action person has to come with to prove his iman and to show that he has belief is what is to pray if he does not pray and he doesn't then the claim of having to say that i believe in الله and the day of judgment it doesn't exist so as i said to you your salah is a symbol and a sign for your belief and if you leave it you've left islam the same is the salah has conditions and it has prerequisites and it has pillars and it has obligatory things if you don't come with them your salah will also not exist so one of the things that we need to talk about is a pillar a pillar in the salah without it the salah doesn't exist and that is standing a standing in the prayer is a and there are many verses in the quran that show that الله سبحانه وتعالى يسأل in the quran وقوموا لله قالتين stand up for الله تبانك وتعالى قيام and the prophet Muhammad also said صلوك ما رأيته موني أصلي pray the way you see me praying and the prophet prayed standing up وقاموا to say الذي كان يقوم بالقراءة إن شاء الله تعالى when we go to the shahrح of صفة صلاة النبي will speak more about that narration إن شاء الله تعالى The man who came to the Prophet ﷺ a Masjid and he said السلام عليكم يا رسول الله after he prayed the Prophet said إدهب فصل لي فإنك لم تصلي Go back pray you have not prayed Go back pray you have not prayed So the man went back and he prayed he came back the Messenger ﷺ إدهب فصل لي فإنك لم تصلي Go back pray you have not prayed After many times going back and coming back and coming back and coming back The man said to the Prophet Oh Messenger of Allah This is all I can do Wallahi I can't pray better than this So the Messenger ﷺ taught him how to pray This hadith has got so much فوائد and benefits in it So the scholars refer to it as What the hadith of what المسيء صلاةه The one The one Who prayed incorrectly That's what the hadith got referred to What did the Messenger come on him He said to him إذا كمتا إلا صلاة إذا you stand up to the prayer Stand up is what the Prophet said فأس بغل وضوء Make sure you make the وضوء reach every part تم مستقب للقبلة فكبر Then face the قبلة and say الله أكبر So this is what What is the Prophet come on to him Stand up Once you stood up Or you want to stand up For the prayer This is what you do And anybody Who leaves off a pillar And the man he has knowledge Number one مختار اللي فعلي And also he's He's the one who chose it He wasn't forced to do it He wasn't under any dress He chose it from his own will And it is also قادر He's able to do it As I mentioned قادرا علما مختار اللي فعلي Those three Anyone who doesn't come on any pillar Are you able to do it نعم Do you know نعم You know the ruling Said one is what You also It's your choice مختارا لفعلي Anyone who leaves that Off a prayer بارطلة بإجماع العلم Your prayer is part If you leave that Leave that pillar And this is a consensus وقد نص على الإجماع The person who mentioned this إجماع إبنوه بيرا إبنو حزمن النووي إبنو قدامة وغيرهم من أهل العلم Other than them from the people of knowledge And insha Allah Don't worry We will bring every one of them Their statements So This is something you have to understand But This حكم that we just mentioned right now لا ينطابقوا على صلاة النافلة But that doesn't It doesn't deal with The voluntary prayers The voluntary prayers The حكم is different The reason is because The Salah which are نوافل تتشوف الشريعة إلى فعليها The Salah has desires for you to come with it واتتسامحوا في بعضي And then the Salah is also if it gives you And allows you And lets you go on Some of the actions of the نوافل So a person is allowed To pray a نافلة Sitting down Even though he has the ability He is allowed to sit down And pray He can sit on a chair He can sit on Whatever he wishes Even though he has the ability To do it But But His prayer is going to be Half of the one who is standing Based on The Hadith of Imam al-Bukhari And narrated by The Hadith of Imran ibn Hussain That the Messenger SAW said The Messenger said The one who prays Standing up Is best أفضل سغة المبالغة صحيح على سؤالة وزلي أفعال The best ومن صلق عدا And anyone who prays Sitting down فاله نصف أجل قائم He gets half of the reward Of the one who is Who is standing up ومن صلق ومن صلق قائم And the one ومن صلق نائم Sorry And anyone who prays Sleeping Lying down فاله نصف أجل قائم He gets half of the reward Of the one who is sitting And this is also transmitted That the Messenger SAW في آخر حياتي In his last stages of his life SAW He used to pray Sitting down The Hadith of Aisha رضي الله In the Hadith of Aisha When she found the Sahih Muslim She said لما يموت رسول الله The Messenger did not die حتى كان كثير من صلاته وهو جالسون A lot of his prayers They used to be A lot of his prayers They used to be Sitting down عليه الصلاة و السلام My beloved brothers and sisters I've already dealt with One top one point right now In the مقدمة مقدمة is three points I'm going to be speaking about The first one is done And that is what The Salah has أركان لا تصحبها Without it The Salah won't exist And I said If the person can do it with what If he's got قدرة He's got علم And he has the choice He has to do it صحيح And if he doesn't فصلاته باطلة بإجماع العلمة His Salah is batin By consensus of this color صحيح And I said this consensus was built by مقدمة The second point that I'm going to I'm going to speak about شاء الله is what Pay attention here The second point that I'm going to speak about which is The عبادات The acts of worship that we come with Is Connected to متوقف It is connected to What على الاستطاعة و القدرة It is connected to our abilities It is connected to Our استطاعة و قدرة Our ability So any Muslim Who is unable to stand for something He can't do it Because he's unable to do it Whichever pillar is in the prayer Such as القيام الرقوع السجود Or other than them فهو معظورو شرعان In the shari'a you're excused You're excused And also you're excused عقلان صح Based on the ayah of the Qur'an و الله تباركه تعالى He says لا يكليف الله نفسا إلا وسعها That الله does not burden a soul More than what it can carry Also the Prophet Sorry الله تباركه تعالى He says فتقوا الله مستطاعتم فتقوا الله مستطاعتم فيه الله Be conscious of Allah Based on what مستطاعتم تقوى الله It is connected to your ability وقوله أصدستيق من الله تباركه تعالى وما جعل عليكم في الدين من حرج الله has no place In this religion اي حرج اي بادن On you Also قوله تعالى And also in the statement of Allah يريد الله بكم اليسرة ولا يريد بكم العصرة Allah wants ease for you He doesn't want hardship for you سبحانه وتعالى يريد الله الله wants for you بكم اليسرة الله wants ease for you ولا يريد بكم العصرة And Allah does not want hardship for you Brothers and sisters Pay attention to this This is very important This is very very important Following the Sharia As it is And adhering to it Saying That that is what That that is Extra and OTT Is معارضة لكتاب الله It's opposing his verse Because every single thing The way Allah legislated It's Yusr It's ease Yusr Hardship comes When the people go overboard But what Allah سبحانه وتعالى Made obligatory Wherever Allah تبارك وتعالى Made sunnah Wherever Allah تبارك وتعالى Made مباح Wherever Allah Made مكروه Wherever Allah تبارك وتعالى Made حرام Everything the way it is Is ease So if you say That something Allah Made حرام Is hardship This is what This is going against his verse It's very dangerous Also the hadith Which is found In بقاليا المسلم In حديث أبي هوريلا That the messenger صلى الله عليه وسلم He said إذا أمرتكم If I command you بأمرين أي ماتا فأتوا منه مستطاعتهم Come with that matter According to your abilities إذا أمرتكم If I command you بأمرين أي ماتا فأتوا منه مستطاعتهم If I command you بأمرين أي ماتا فأتوا منه منه مستطاعتهم Come with that thing Which I have commanded you Come with it According to your ability Pay attention والله Brothers and sisters We have to understand the source The prophet didn't say Leave it He said Come with it You what? You have to come with it Because the prophet commanded you To say I am unable to do it In totality It's not what the hadith is saying So you there The evidence What does it want from you?  Look at this Pray standing up is a command But then look what it was said after that فإن لم تستطع But you are not able Then sit down But then I am not able To sit down as well Then ok Pray on your side أنا سبنو ماليك رضي الله تعالى عنه The Hadith in Bukhari المسلم سقط رسول الله The messenger fell down عن فارا سيد He fell from a horse عليه صلى الله عليه وسلم فخودي شا أو جوحي شا شقه الأيمن The messenger صلى الله عليه وسلم injured his side Some narrations mentioned his shoulder عليه صلى الله عليه وسلم He injured himself You see What the messenger صلى الله عليه وسلم did was He stayed in an attic He left all of his wives And he said I am not going to stay with them for 29 nights So he stayed in an attic عليه صلى الله عليه وسلم The Sahabas came and they visited him فدخلنا عليه نعوده We came and we visited him فحضرات الصلاة The Salah came فصلى قاعدا The messenger صلى الله عليه وسلم praying sitting down وصل لنا خلفه And we prayed behind him قعودا We prayed behind him Sitting Some of the narrations mentioned that The Sahabas prayed standing up And the messenger صلى الله عليه وسلم He told them to sit down عليه صلى الله عليه وسلم الإمام النووي And Ibn Qudama رحمه الله May Allah have mercy upon both of them They have brought a consensus That the عبادات Is متوقف على الاستطاعتي والقدرتي That the عبادات Are connected to the person's ability We put ayat, right? We put hadith, right? Now we're bringing إجماع And that's how I manage قرآن سنة إجماع إجماع is قو الإمام أبن قدام And Noah we brought it And others brought it But I'm just going to suffice myself with these two إبن قدام رحمه الله He's selling this Kitab Al-Mughri First volume page 443 أجمع أهل العلم على أن من لم يطبق القيام له أن يصلي جالسا إبن قداما أجمع أهل العلم The scholars are unanimously in agreement The scholars and the people of knowledge On what على أن من لم يطق القيام The one who's not able to pray He's not able to له it is legislated And it's permissible for him أن يصلي جالسا To pray certainly وقال النووي وان إمام النووي He said In his Majmu'a Fourth volume Page 182 He says أجمعت الأمة The Ummah are unanimously in agreement على أن من عجز عن القيام في الفريضة The one Who is unable In standing In obligatory Is unable to stand Praying صلاح قاعدا He prays it sitting وإلا ولا إعادت عليه And there is no repetition from him I mean he doesn't have to repeat it ولا إعادت عليه And he doesn't also have to repeat it وقال المرداوية الإمام المرداوية رحمه الله He said in his Kitab al-Insaf The second volume Page 305 He said بلا نزاع Without any نزاع and discussion And debate about that That's what the pastor needs to do And of course As it is It is Evidence from the Quran And the Sunnah And the Ijmaa I also goes And the Qawa'id al-Fikia That we studied Which is لا ضرارا ولا ضرار And the Qa'id المشقة تجلب التيسير And the Qa'id لا واجب مع العجز And the Qa'id الضرورات To beeh المحضورات So he goes Hand in hand With all of those Qawa'id al-Fikia Which we have Spoken about So Based upon that It is upon every Muslim Who is unable To come with Wherever pillars of the Salah Wherever arcane of the Salah is To know that he is what Excuse By the Quran And the Sunnah And the Ijmaa So what about If I am unable to stand up In the prayer What do I do The person prays Sitting Are you there If I can't stand up And I'm unable to stand up What do I do Sit down Based on what حديث حديث بعمراني بن حصي رضي الله تعالى النصح البخاري The Prophet specifically said to him صلي قائما فإن لم تستطيع فقاعدا فإن لم تستطيع فعلى جنب So You can't stand What do you do You sit down Good ومن عجز علي الرقوع What about the one Who is unable to come with a rقوع He can't come with a He can't come with a He can't come with a He can come with it He can come with the قيام But he can't come with a rقوع What does he do This is very important These points are very important The person He can come with a قيام And he can come with a But he can't come with a rقوع For example Whatever reason it may be This person it will be said to him When you're standing up Go as far as you're Able to go In other words حال قيام While you're standing up You Go a bit down Are you there What about if the person Can't do sujood He sits down And then he does it from there As far as he's Able to go He moves it down As far as he can go Pay attention This is very important You're not allowed to Do the rقوع From the Sitting position And you're not also Allow to do the sujood From the Standing position Because the closest The rقوع is Is to the قيام And the closest That the sujood is Is to the julu sitting So the Am I crystal clear In what I'm saying So when you're standing That is when you're closest To rقوع So you do it With your head like that Pay attention now The rقوع And the sujood Also has to be different Even though the positions Are different anyways Because this one's قيام And you're doing it With your head like this The sujood Should be what Always Slightly moved down And there's a hadith That is narrated Which is not authentic A hadith of And he also narrated it They attributed To the Prophet And he said يوصلي المريض قائمة The sick one Praise standing up فإن لم يستطيع If he's not able to And yes جدا He's not able to do sujood Or ماء He does He points it out With his head like this That's how he does it وجعل sujood أخفض من rقوع And he makes His sujood More than his rقوع فإن لم يستطيع يوصلي قاع If he's not able to pray Sitting صل على جنبيه He prays on his sides On his right side الأيمن مستقبل القبلة But facing the qiblah And the way they said That he should face the qiblah Is that his legs should face the qiblah If he's lying down His legs should face the qiblah Because when he does the rقوع And the sujood sitting Or lying That it is His heads towards the If he's on his right And his legs towards the qiblah When he does his rقوع He's facing towards The qiblah they say That's what they said But this حديث لا يسحر It's not authentic لأن مداره Because what it revolves around Is a man by the name of حسن ملوحسين العراني And he is a مطروك الحديث وكان من رؤوس الشيعة He's from the heads of the Shi'a He's from the heads of the Shi'a And also Also From the inner chain is الحسن ملو يزيد أما الحسن ملو يزيد And he is weak as well But What is authentically transmitted موقوفا موقوفا عن جابير It's a statement of Jabir وليسحر مرفوعا And it is not authentically From the Prophet عليه الصلاة والسلام He's what صلي على الأرض انستطعته Pray On the earth If you're able to وإلا if not فأو ميماءا شو A showing with your head like this واجعل سجودك أخفض من رقوعك And make your سجود More down the aruku So if you're sitting right now Are you there Are you able to do the aruku And the sujud because you're sick You can't even stand up a Salatan Both of them has forced you to sit down right What's the difference between the two The aruku and the sujud here The aruku is more up And the sujud is more down ابل القيم رحمه الله He said in his كتاب بداعي الفوائد The third volume page 1155 He says جعل سجوده أخفض من رقوعه ليه تميز أحد وما عن الآخر The reason why The sujud is more down Than the aruku Is to distinguish one from the other وعليه I'm based on that ابل القيم says I'm based on that فإنا نقول we will say من قدر على القيام أو القعودي Anyone who has the ability In standing or sitting وعجز عن الرقوع أو السجود And he is unable to come With the aruku Or the sujud فإنه يوم أبيهما What he does he does فيوم أبي الرقوع قائما So when he's standing He does it from his Like that وَبِسُجُودِ جَالِسَنْ And the sujud He does it from when he is sitting أيه؟ How does he do it? مُفْتَرِشَنْ أو مُتَرِكَنْ The sits are two right One time you sit on your leg And one time you don't sit on your leg right Whichever of the two it doesn't matter وَقِلَ يَجِلِسُ مُرَبِّعَنْ Even if you want you can cross your legs When you're sitting You got three ways of sitting You can either do مُفْتَرِشَنْ The last تحية how do you do it You don't sit on your leg right أو you sit on one of your legs أو you cross your legs You actually cross your legs The way you're sitting now It's called مُتَرَبِّعَنْ You can sit like that when you're praying If you're sick and you can't get up You're sitting The position can be like that لقولي عائشة رضي الله تعالى عائشة سن رأيته رسول الله I saw the prophet of Allah يصلي مُتَرَبِّعَنْ I saw the prophet of Allah praying like that رأيته رسول الله رأيته رسول الله نعم نعم نعم رأيته رسول الله ألمام النساء يناريته ابنو حكومة الحاكم ابنو حبان ورجانه وثقاته و this is the statement of ابنو القيم So here we learn from it If a person is able to stand And he's able to sit But he's unable to do the رقوع or the sujood He does it from the positions Which are closest to it So the قيام is the closest to it So you do ايماء from there And the sujood you do it from there Sitting that is the closest to it But if you're unable to stand Or you're unable to sit So you're unable to stand at all You're unable to stand anymore You can only sit Then if you're in this position What you do is you bring the رقوع And the sujood is sitting Because that's what you can do right But then you distinguish between the two In one way By making sure that the رقوع Is a bit higher And the sujood is much lower That's the قيام رحيم Very good What about if the person is Unable to If he's unable to pray on his side If he's unable to pray on his side The حديث عرل behind him So if he pushes to the side He's unable to do it Then the scholars they said صل على أي حال He plays it in any way he could So أون على ظهري If he wants he can lie down نحيا جهس when people are in coma or not coma sorry he's really gone he doesn't have to pray but what i mean is I a person who's conscious paralyzed is conscious his mind is there but he's he just can't move for whatever reason it may be then this individual if he wants to come pray if he's like that he prays lying down the way it is are you there or sometimes a person ربما أنه لا يستطيع إضافة أيضاً. يجب أنه في مكان where he's sitting, يجب أن يبقى إضافة هل أنت there on a chair, and he prays like that. في ذلك الوقت هو أنه يستطيع إضافة كيف يستطيع إضافة. ببعض على محاولة الله which is what now you can leave for Allah نفسا إلا وسعها فتقوا الله مستطاعتهم إذا أمرتكم بأمر إنفقته منه مستطاعتهم ببعض على كل ذلك. now that we've said that everybody pay attention here who was unable anybody who is unable, we're still in second point, anybody who is unable to come with a pillar من أركاني الصلاة from the pillars of the Salah or any other عبادات wherever it may be or any other عبادات شرعية فإنهم عدوروا شلعن. we already spoke about that he's excused right? he's excused right? but what he also needs to know is that you're not just excused rather you have the full reward your adhan and your reward is as though you prayed that prayer fully. what I mean praying fully is that you have come with it as it should have been initially. if you're praying sitting down because you're unable to do it you get the reward of the person who's praying standing up at the same reward. and the evidences of the Kitab and the Sunnah show this. the message of the Sallallahu Alaihi Wasallam he said in the Hadith which we find in Sahih Al-Bukhari من حديث أبي موسى ألش علي رضي الله تعالى عنه إذا مريض العبدو if the slave becomes sick or safara if the slave becomes sick or safara or he travels كتب لهم من الأجري the reward will be written for him مثلما كان يعمل الصحيح المقيمة he will receive the reward of a person who is healthy and he is a resident in the land. if you're a traveler you pay attention here. you leave off some things right? things you don't have to do. صح? every single thing that you left. for example when you're traveling you leave a thought. fasting. are you the same in reward with the one who is fasting? نعم. you used to fast every Mondays and Thursdays. or you used to fast a fasting of Dawood علي السلام. you used to fast the fasting of Dawood which is كالي يسوم يوم و يصطر يوم. you used to fast one day and miss a day. so you do that kind of fasting but then قدر الله و ما شاء الله فعل you traveled and you couldn't fast. you get that reward like as though you're fasting nothing. that's the evidence for it. also the messenger صلى الله عليه وسلم I told I asked the hadith of a Muslim من حديث سهر بن حني في رضي الله تعالى عنه that the prophet said من سأل الله الشهادة بصدق بلغه الله منازل الشهداء وإن مات على فراشه the messenger صلى الله عليه وسلم I said من سأل الله anyone who asks Allah الشهادة he asked Allah that Allah kills him the shaheed fighting with the enemies of Islam the kuffar بصدق and he asks him with صدق truthfulness بلغه الله منازل الشهداء الله will make you reach the stations of the martyrs وإن مات على فراشه even if you die in your deathbed even if you die in bed even if you die in bed شيخ الإسلام ابن تيميا أز البعلي الحنب حنبلي in his اختيارات الفقية page 102 he said ابن تيميا said ومن كانت عادته الصلاة في جماعة أو الصلاة قائمة ثم ترك ذلك لبرض أو سفر فإنه يكتب له ما كان يعمل شيخ المقيم ابن تيميا said anyone whose norms عادت to his norms and how he normally was الصلاة في جماعة he would pray the prayer in a congregation أو الصلاة قائمة or he would pray the salah standing up ثم ترك ذلك and he left of that he left of the جماعة or he left of praying standing up for what reason because he became sick أو سفرين أو he's a traveler and the traveler cannot refer to as a person who is the قيام you can't miss that for this traveling فإنه يكتب له ما كان يعمل وهو صحيح المقيم you it will be written for you what you used to do when you were healthy and when you were resident so what stopped you from this right now is because you're not healthy and the fact that you're not a person who is who is a resident your traveler also he said the 23rd volume page 236 he says و أما محتج به منازعه من قوله إذا مرض العبد أو سافر كتب له من العمل ما كان يعمله و صحيح مقيم فوجوابهم أنه أن هذا الحديث دليل إبنو تيم is talking about the discussion and the debate with somebody and he broke the hadith and what the response to them is أن هذا الحديث and this is the evidence على أنه يكتب له that it will be written for the person مثل الثواب الذي كان يكتب له في حال الصحة والإقامة it will be written for him the reward in which الذي كان يكتب that which we used to be written for him في حال الصحة when he was healthy while إقامة when he was a resident لأجليليتي all of that because of his intention that he is excused because he is unable to do so و هذه قاعدة قاعدة الشريعة قاعدة of the sharia a principle of the sharia أن من كان عازما على الفعل عازما جازما anyone whoever that person may be who has conviction unwavering conviction determination of something وفعل ما يقدر عليه أنه does all that which he can كان بمنزلة الفاعلي than he is he does all that which he could but he is unable to really do it but he push, he comes with whatever he can then he gets the reward of the person who is fully done it فهذا الذي كان له عمل في صحته وإقامته عزمه أنه يفعل وقد فعل في المرض والسفر ما كان له فكان بمنزلة الفاعلي فما من لم تكن عادته الصلاة في جماعة ولا الصلاة قائمة إذا مريض فصلاة وحده وصلاة قاعدة فهذا لا يفتب له مثل صلاة المقيم الصحيحي تفكير لو كان هذا ليس التقنية وخلافا إذا لم تكن لديه لماذا كفروا بالداب إذا قرأت to pay Qiyamul-A'il عندما تكون مزاعدة إذا قرأت to travel, what would be written for you ما سوف يكون لدي قيامو الليل ولكن على أي حالما أردت to pay Qiyamul-A'il أقوةWhen you're fine and you're healthy وينما تكون مزاعدة ف ف now it won't be written for you ولا يوجد مناسب وعندead who we're going to speak about في مقدمة ويتاقشة لذلك يجب أن تتذكر أن فضل المتعليق الفضل المتعليق بذات العبادة أولى بالمراعات من الفضل المتعليق بمكان العبادة أو زمانها الفضل المتعليق بذات العبادة أولى التلقين بشكل أهم من العبادة وكما ذاك اللغة أو إبقاء الذي يضع لك في المكان ومن الشيء الذي يخلصه بالحافظ هو بشكل أهم أولاً من خلفي فأرة أمي المقة كعباء الله أولاً أن نقص جدًا بصراحة التي تصل إلى المبارس أو الأمر التي أكدت قطلة لرغم المنطقة المتعاقية العالمية التي قام بكعبة مكة على مالكا مالكا فرق مكة؟ قطلة مكة تكفلت هل تريدين؟ لذا here what we say is in this situation is this individual as a Muslim the shariah wants you to come with a prayer that's what most important here the salah the essence of the prayer is more important هل تريني؟ هذا تأخذ أكثر مجرد من ماذا؟ أكثر من رقل الصلاة الصلاة تأخذها تأخذها تأخذ مجرد إذا كان هناك مالذي يحدث هو؟ تأخذ هناك إجابة التي يوجدها المجرد لا يمكن أن يكون مجرد لكن المجرد لا يمكن أن يكون مجرد أصبحت شريع will give more importance to the essence the Salat itself because that takes presence over the pillar just like the prayer itself takes presence over the the time and the place so that's why the shri'a will excuse you if ability goes if ability goes the shri'a will excuse you for some pillars but it will not excuse you for the prayer so I'm going to conclude there إن شاء الله إذا أتفق سأذهب إلى أحكام الصلاة والقراسي في الأشياء ومكتبوا عن طريقة التي حدثتها والأشياء والأجهزة وماذا لا تستطيع أن تكون؟ وماذا لا تستطيع أن تكون؟ وماذا لا تستطيع أن تكون؟ أي شيء يمكنني أن I have said that was wrong or a mistake فإنه مني ومن الشيطان هذا الشيطان هو مني الشيطان لأن الله his messenger is free from it سبحانك الله وبحمدك الشهد أن لا إله إلا الله أستغفروك وأتوب إليك


In the previous lecture, we have looked at various components of the VHDL language. We have looked at object types, we have looked at data types, we have seen how physical quantities can be represented with units and then we had seen how composites and various user defined types and subtypes can be used in VHDL. This defines the basic structure of the language. We now want to look at the styles in which we design or describe hardware using VHDL. We first look at structural description in VHDL. As we have discussed earlier, structural description means that we have to name all the components that we are using in a circuit and give a list of connections from one circuit one sub-circuit to the other. Therefore the language must provide the wherewithal for placing these components of hardware, attaching these components with a particular kind of behavior and a list of wires which will connect pins of this sub-circuit to pins of other sub-circuits. All the devices in the language which cater to this requirement, they are described as structural description languages, structural description commands and those are the ones that we look at at first. So therefore structural description consists of these parts. You have component declarations in which you declare the properties of each component that you would be using. Component instantiation in which you actually place the component at various positions in the circuit. The configuration refers to the choice of binding this component to entities to architectures and so on and very often we use multiple components of the same time and therefore it is convenient to have a repetition grammar. To give you an example, you might have 8 registers in a particular design. The register is declared as a component and described it maps to a particular entity architecture pair. However you do not need just one register, you need 8 and it is painful to go ahead and describe each instantiation of this component type called register and therefore it is convenient if you could using repetition grammar place 8 instances of this type of component. So therefore repetition grammar is an important part of structural description in BHDN. Let us look at the look at some circuit and see how we shall go about describing it structurally. So the structural design describes a design in terms of components and their interconnects. Each component declares its ports and the type and direction of signals that it expects through these ports. This is very similar to the declaration of an entity. So the next part is how can we describe the interconnects between these components? And we take this example, you have 3 components here u1, u2 and u3 and each one has its own declaration of various ports. So for example u1 has p1, p2, p3, p4, p5 and p6, u2 similarly and u3 similarly these might or might not be identical components. Now once we have instantiated these components the rest depends on how do we tell VHDL that p1 of u2 is in fact connected to p5 of u3 and so on. These are done using internal signals. So for each internal interconnect we define an internal signal. When instantiating a component we map its ports to specific internal signals. For example in the circuit above at the time of instantiating u1 we map its pin p2 to signal s2. Notice p2 is connected to this signal s2. So when we instantiate u1 we not only place a kind of component a component type here but we say that p2 of this instance of this component must be connected to the signal called s2. Similarly when instantiating u2 we map its pin p3 to s2. So u3 is a component, u2 is a component and u2 is mapped to a component type and when we instantiate that component type we shall map its pin sp3 here to that same signal s2. Therefore it is known to VHDL that pin p2 of u1 is connected to pin p3 of u2 through the signal s2. Now a purely structural architecture for an entity will consist of first of all component declarations. What this does is it associates a component type not individual instance of a component but a component type with their port list. It is very similar to an entity declarations. You also need signal declarations so that you can then use those signals to connect one component one instance of a component to another component. Component instantiations to place component instances and to port map their ports to signals. The pins can be connected either to internal signals or to the port signals declared by the entity which is now being described. We also need configurations. These configurations will bind component types to entity architecture pairs and these configurations can be in line that is they could be part of the architecture or they could be standalone units outside the entity architecture description. In addition to these basic requirements we require a repetition grammar for convenience. This is for describing multiple instances of the same component type. For example you have let us say 1024 memory cells all of them are identical it would be indeed very inconvenient to have to describe each instance of a memory cell individually and it makes a life much simpler if we could if we could just place all 1024 of them using a repetition grammar. Similarly a very large bus may have buffers associated with each line of the bus and it is convenient if we have a repetition grammar which will describe the placing of all these buffers in one go. So these are the components that we need for describing hardware structurally. And let us look at many of these components of the language as we go along. First is a declaration of a component and these are VHDL 87 and 93 versions of the component declaration. It declares a component type not a specific instance of a component and it is very similar to the entity declaration that we have seen earlier. I shall not drag you through the differences between VHDL 87 and VHDL 93 every time it is here for you to see and it is better to get used to the more consistent style required by VHDL 93. So in the discussions we shall mostly look at the VHDL 93 style of declaration. So then you have the declaration says component that is a keyword what appears in bold letters here is a keyword. So component and this is the name of this component type. So component name is is is also a keyword and then the list of all the generics and the list of all the ports. So remember this list is essentially the same format as a record data structure that we had discussed last time and then end component name. For example we can say component flip-flop is that means this declaration is describing a component of the type flip-flop. Generic t-prop which is the delay length which says what is the propagation delay of this flip-flop. And then a port list saying port clock and D as input and these are of type bit and Q as type output and bit and finally end component flip-flop. This format is identical to an entity declaration but be aware that you are not describing an entity here you are describing a component which will then be bound to an entity architecture. Because of this similarity in fact in VHDL 93 you need not declare a component type separately if you are always going to use the same entity architecture pair for this component and in such cases you can directly instantiate entity architecture pair. This option was not available with VHDL 87. So this is what we have been talking about in VHDL 93 you can do direct instantiation that means an entity architecture pair can be instantiated to specific pieces of hardware without having to go through a component type declaration first. So this is an instance name notice now I am not declaring a type of component I am declaring a specific part of the hardware for example this could be our U1, U2, U3 that we had seen those are specific instances so you have the instance name and then the keyword entity which wants the language that I am not using a component type I am going to instantiate an entity directly. So instance name could be U2 for example and then the keyword entity it will appear entirely like this E N T I T Y and then the name of the entity and within bracket the architecture which you want to instantiate. So this entity architecture pair is then instantiated into a specific instance of hardware here and then you have the generic map and the port map as before. Notice that this port map now will be for this specific instance that means it will bind those pins that you have declared in the entity to specific signals. This form is convenient though it does not have the full flexibility of associating alternate entity architecture pairs with a component because when you instantiate the component you have already bound bind this is this is already bound to an entity architecture pair. VHDL 87 did not allow the direct instantiation and because it permitted only component instantiation this keyword was not there at all it was taken for granted that only components can be instantiated whereas in VHDL 93 you can you have both options if you directly instantiate an entity you will use the keyword entity otherwise you must use the keyword component. So this is the normal instantiation when you have declared a component type and then you have instance name this is the specific instance that you are placing the keyword component then the component type name now and then the generic map and the port map. The association here is with the previously declared component type the type will be bound to an entity architecture pair using an inline configuration statement or a separate configuration construct. In VHDL 87 the keyword component is not required to be used because the only option you had was of instantiating component type. So there in that we used to use instance name and no keyword component directly the name of the component and then the generic map and the port list. Now let us look at configurations and the simplest of these is an inline configuration that means the binding of a component type to an entity architecture pair is made inline with a use clause. So for example we say for all component name that means you are now saying that whenever the component name flip flop is invoked then for all instances of this use the entity with this entity name and with this architecture name. You also have the option of not saying for all you could specify specific instances and bind some instances to one entity architecture pair and other instances to other entity architecture pairs. So this is the additional flexibility you will get if in fact you are using inline configuration or indeed a standalone configuration. So in that case instead of for all you will have an instance name list you might say for example that U1 U2 U4 and then component name and then you say use the entity these two are keywords and must appear verbatim in your description and here comes the name of the entity that you will be using and here is the architecture name. So these lines then constitute a configuration it simply says that when an actual instance is being placed we know eventually which entity architecture will be evoked when its sensitivity has been hit. If we use the keyword others instead of a list of instance name it refers to all component instances of this component name which have not yet figured in a named list. In VHDL the keyword others is used in different contexts involving lists and if some members of the lists have been specified then others refers to the remaining members. If none was specified it is equivalent to saying all. So recall we had said for all here. If we do not give a list and use others then that is equivalent to for all on the other hand we could give say U1 U2 and use some entity for that and then say others that means all other instances of this kind of component will use the entity name architecture name given in the other statement. Now this configuration could be hierarchical remember we are when are we using this we are using it in an architecture of some higher level component that means we have a higher level component which consists of a more detailed description using lower level components in the hierarchy. So therefore these configurations and such statements etc are going inside an architecture which happens to be structural in nature. So in that architecture we could use an inline configuration or indeed use an external configuration by specifying its name. Now this architecture will then specify a component type remember this component type will then be mapped using the configuration to an entity architecture but that architecture itself could be structural therefore we need to bind the components of that lower level architecture also by a configuration and therefore the configuration itself can be hierarchical. For example you could say in the current architecture U1 is a component this U1 is then is some component type which is mapped to entity E1 and architecture A1 but A1 uses some other components and they must then be bound to entity E13 and component and architecture 13. So therefore this binding can percolate down the hierarchies and such configurations are called hierarchical configurations. So this hierarchical association within an architecture you have a component that component is marked to an entity architecture and that architecture has other components and so on. So this hierarchical listing of components can be done once and for all in a single configuration. So here is an example hierarchical configuration can be fairly complex and VHDL contains fairly complex configuration statements. We now introduce a very simplified construct here which is an inline configuration. So for example you say configuration this is the name of that configuration this is actually a standalone configuration in that case. So configuration and this is the name of this particular configuration of this is the entity name is for such and such architecture of this entity. So remember the configuration is a standalone unit it has its own name and then it says that I am describing the configuration of this entity whose name is this and then for such and such architecture of this entity and within that architecture for this component instance name list use this component type name which must use then the entity such and such entity lower level hierarchical entity with such and such architecture. And notice that you have two fars here and both fars must be ended. This can then be followed for some other architecture of the same entity indeed inside this for architecture you could have for these component instance lists map thusly and for other lists map in a different way. So this whole construct forms a hierarchical configuration by itself. Let us illustrate it by an example. So this is in fact an XOR gate and we are constructing this XOR gate using NANDs. The inputs of this whole thing is an entity and this interconnection is in fact the structural architecture for this entity. This structural architecture uses four instances of the same component type which happens to be a NAND. So you have a component type called NAND and there are four separate instances of this component type NAND. So therefore you need to describe the NAND gate first. So in VHDL you describe entities and architectures and these are then compiled into a special library called work. The work library does not have to be specifically declared. So if you invoke some components which you have just now described then you do not have to invoke a library. On the other hand if you invoke components which were described elsewhere maybe by somebody else then you have to declare a library and then invoke the use clause to use those things from a specific library. So in some sense the work library represents the current state of the development of the project for designing something. So let us now build upwards from NAND here. We say entity NAND 2 is notice we are declaring now an entity. This is the elemental level entity of a simple to input NAND. This is our port list we are not using any generics here. So the port in 1, in 2 are inputs and are of type bit whereas P is of output direction and type bit and entity NAND 2 that is all there is to the entity NAND 2. Then we describe an architecture we happen to call this architecture trivial then architecture trivial of NAND 2 is and then we say assign to P the value of not in 1 and in 2. So this describes how P is the NAND of in 1 and in 2 not and and are built in logic functions. Now that we have this entity architecture pair we can use these to build our XOR gate. So now our work library contains this description of the entity NAND and this architecture of entity NAND 2. Entity is called NAND 2 the architecture is called trivial and it is the architecture of NAND 2. Now we want to build this XOR gate that we had specified we say use work dot all that means everything described in work is to be recognized as something to be used and now we declare the entity XOR. So entity XOR is and now we declare the ports of XOR now. So port A B are inputs so A B are inputs and of type bit and port AXB this is the name AXB is the output and is also of type bit and then finally NAND entity XOR with this we have declared the entity called XOR. Now we need an architecture for this and we happen to call this architecture we happen to name it as simple architecture simple of XOR is now remember we have to declare component. So component NAND 2 in is and if you recall components are declared the same way as entities are. So we declare that component NAND 2 in is and this is the port list port A B in bit AXB output for all NAND 2 in use entity NAND 2 with the architecture trivial recall that NAND 2 with architecture trivial was declared earlier in the work library. Now the architecture begins and the architecture is simply a list of instantiation because it is structural with all the signals that we should have declared earlier. So signals S1, S2, S3 which are the internal signals must be declared earlier and that is what we have done here signal S1, S2, S3 bit. Now we begin here and this is A B and then this is instance N1 notice all instances they are all NAND gates but they are separate instances. So N1 is an instance and we tell the language that we are instantiating a component we are not directly instantiating an entity architecture pair. So we use the keyword component and NAND 2 in is the name of the component recall that this component was declared here. So we say that instance N1 is it uses a type called NAND 2 in and it is to be port mapped to A, B and S1 that is to say A and B are port signals and the output is to be mapped to an internal signal called S1. Similarly we can instantiate N2, N2 is this instance of NAND. So N2 will use the component which we have declared earlier in our work library called NAND 2 in and we shall port map it to A which is a port signal and to the signal S2 which was the output of NAND N1 here. So A and S1 are then its inputs and then S2 is a new signal and that is its output. Similarly we instantiate N3, N3 again keyword component name of the component NAND 2 in and then we port map its ports to B which is a port signal of XOR, S1 which is the internal signal which is the output of N1 and then this new signal S3 which is its output. And finally we instantiate N4, N4 is also of the component type NAND 2 in and we port map this instance to inputs being S2 and S3 here S2, S3 these are the outputs of N2 and N3 as you can see here S2 and S3 and its output goes directly to the port AXB of the XOR. So with this now we have described the entity architecture for an XOR. We can now map a component to the entity architecture pair naming the entity as XOR here entity XOR with the architecture simple. So now XOR becomes a component and from now onwards we can use XOR as a component type just like we use NAND 2 as a component. Let us have a look at their repetition grammar. We frequently use a large number of identical components of the same type. We had looked at this example before for example we could be using a large number of memory cells or bus drivers or what have you. Now it is tedious really to instantiate and configure each one of them individually. So recall all this work that we did for N1, N2, N3 and N4 would have to be done for let us say 1024 components of a 1K memory and we can have much larger repetitive components in VLSI. VHDL provides a way to place a collection of instances of a component type at one go using a statement called generate. This that generate is interpreted and handled before the simulation actually begins. So this is in that sense a macro of the language so to speak that means the hierarchy is expanded before the detailed simulation occurs and generate is interpreted as essentially something which relieves you of the repetitive description process. From that point onwards the description will use this expanded form which is internally set up. So let us look at the generate statement. The generate statement contains a for loop which takes effect during the circuit elaboration step. So I had said that before the simulation begins there is an elaboration step and during elaborating the circuit we make use of the generate statement. After elaboration has been done it is as if the generate statement is not there in your description because the effect of this has already been expanded out in a more detailed circuit. This statement can be used to repeat instantiation constructs. Indeed in theory a generate statement can be used to repeat any concurrent statement but in actual use it is much more common to use it to repeat instantiation. Let us illustrate this with an example. Here you have a name which is the name of the entire group not a single instantiation or any these are this is the name of the entire group which is then being instantiate. Since this is a repetitive statement it has syntactic constructs which are very similar to other repetitive statements in programming language and we use a for here. So you say for any index here which could be an integer for index in the range 0 to width minus 1 generate. So this is the generate construct it simply says that what follows here and it happens to be between this begin and end pair has to be repeated for the value of an identifier called index which will span from 0 to width minus 1. This whatever follows here is to be repeated that many times. Then you have the begin and this is the instantiation some name followed by the keyword component this will appear verbatim as component. This is the name of the component say out buff and then port map. So suppose we are placing many buffers on a bus the bus is for example 32 bits wide. So then we are saying for index in 0 to 31 generate begin. This is the name of the group saying buffer group component which has to be placed repeatedly the type of that component is out buff and then you port map in terms of this index. So each instantiation will use different signals and the names of those signals will be derived from this index. Now the defined index in the for construct has local scope that means it has scope only inside this. You may use the same name outside the generate statement and that will not be this index. This index has local scope only inside here and can be used to pick specific signals from an array in the port map statements remember this port map is to be repeated. But the port mapping is different for different instances. So we get around this problem by using an array of interconnect signals and the index in that array comes from this. Here is an example you have a full adder this is an example of structural description you have a full adder it has three inputs a b and carry in and it has two outputs some and carry out. We must as always begin with an entity declaration entity full adder is this is followed by a port list saying port a b and c in as inputs of type bit and some and c out as outputs and also of type bit and entity full adder that is all there is to the entity declaration. Remember an entity is a look at this hardware from the outside and from the outside what we see are a b and c in as inputs and some and c out as outputs of course as is conventional some and c out represent the more significant some is the less significant and c out is the more significant bit of the two bit result of adding a b and c in. Now just assume that this is too difficult for us to figure out in reality you will be using much more complicated circuits but we would we just use this example as if designing a full adder is too difficult for us and that it must be a hierarchically broken down. So we would like to decompose this circuit into blocks which handle only two bits at a time. So let us say that we cannot design a full adder from scratch. We would like to describe it in terms of a simpler circuit called a half adder which adds only two bits at a time. So then we can decompose the full adder into two half adders the first half adder adds a and b and produces two outputs some one and carry one this some one is then combined using a half adder with the carry in. So we add carry in to this sum and the output of this again produces two bits s two is the sum of this half adder and that appears as the sum of the full adder. And the two carries need to be combined to produce a single carry out and it turns out functionally that the or of these two carries is the carry out that means if a and b produce a carry in that case the carry out should be one or even if they do not if the sum of these produces a carry from c in then also the carry out should be one. So therefore functionally the carry out of the full adder is the or of the carries of the two half adders each half adder. So now we have described the full adder in terms of half adder we must go hierarchically down and declare how the half adder is going to work the half adder is easy to design each half adder represents the sum and carry of just two bits carry occurs only if both bits are one and therefore it is the and gate. And the sum is zero if both bits are zero or one and one if the bits are dissimilar so this is an XOR gate. So now we have described the half adder in terms of known gates recall that just some time ago we had described the XOR gate as a combination of NAND gates. So now we are down to NAND gates for describing everything else. Now this is how in VHDL we will describe the full adder entity half adder is this is what we need for the full adder port in one into as inputs of type bit and port S and carry these are outputs of type bit and this entity half adder the architecture trivial of half adder is and you assign to S, A, X or B and assign to carry A and B and this is the trivial architecture. Now architecture simple of full adder is now we declare a component type half adder notice we have an entity half adder but we are going through the full route not instantiating the entity directly declaring a component type which is half adder. So we say component half adder is and this component has port A and B as inputs which are bits and S and carry as outputs which are also bits and this ends the component declaration and now we declare signals S1, CY1 and CY2 notice these are the internal signals of the full adder S1, CY1 and CY2 are the internal signals remember S2 is directly mapped to a port and therefore need not be declared as an internal signal similarly A and B are directly available as ports. So it is carry in. So these do not have to be declared as internal signals. So as a result it is only S1, S2 carry 1 and carry 2 which are internal to this architecture and that is what we are doing we are declaring S1 carry 1 carry 2 as the internal signals S2 will be directly mapped to the port sum and then we place these components there are two instances of the half adder. So HA1 component half adder remember we have declared the component half adder here and port map these ports that had been declared here to A, B, S1, A, B, S1 and carry 1 that is this half adder this half adder inputs are mapped to A and B and the outputs are mapped to S1 and carry 1 then HA2 is instantiated this is also the component half adder but this is port mapped to S1 and carry 1 and the outputs are port mapped to sum and carry 2 recall this is HA1 the inputs are mapped to A and B the outputs are S and S1 and Cy1 and then S1 and carry in bar carry in are the inputs to half adder 2 and sum and carry of this are mapped to sum directly here which is the port signal and Cy2 is then mapped to the input of this OR gate. So that is what we are saying HA1 is component half adder port mapped to A, B as inputs outputs are S1 and carry 1 HA2 is also the same component half adder and it is port mapped to inputs are S1 and carry 1 now and outputs are the sum of the entity and carry 2. Now we need to combine the 2 carry into a single carry and the that instance is called combination we have a previously declared component OR2. So we say component OR2 input and port map the OR gate to carry 1 and carry 2 and the output appears as C out of the full adder and this ends the simple architecture. Now let us look at the half adder the carry from the half adder is an AND gate and the combiner eventually is an OR but gates without inversions are slow AND gates and OR gates are slow. So let us improve this design and bring out carry bar rather than carry using a NAND gate a NAND gate is a natural in CMOS implementation. So then we redefine the half adder to produce sum and carry bar remember the sum is an XOR which can be constructed from NANDs as we had seen earlier. So rather than carry using a NAND gate we declare a carry bar. So now we declare a new half adder whose output is carry bar not carry. So entity half adder is port in 1 in 2 as before inputs bits and sum as before but now C Y bar which is an output of type bit and that ends the entity half adder and the architecture better this is new architecture of half adder is and you begin assign to sum A XOR B and assign to carry bar A NAND B this ends the architecture better of half adder this is hopefully faster because it uses only inverting gates. The combiner should now remember the carry is now negated carry is the bar of the carry C Y bar is output therefore the combiner should be an OR of negative true signals whenever is whenever the carry is true the output of half adder will be false. So therefore the combiner should be the OR of false signals and that is just a NAND. So now you have HA 1 with a better architecture HA 2 with a better architecture both giving carry bars and the combiner now is the OR of negative inputs which is in other words a NAND. So now we have the architecture better of full adder which uses component half adder so we declare a component half adder with these ports with signal S 1 C 1 B C 2 B and we instantiate HA 1 and HA 2 which is component half adder port map and so on and then the combination is a NAND 2 and this ends the architecture better. Then we have the efficient full adder which uses this better half adder and the combination is in fact NAND 2 this is this illustrates essentially how to instantiate components we have not instantiates instantiated generics and that can be shown by having a byte comparator which compares to bytes and each internal components is a bit comparator. So essentially we are making a byte comparator to give you an example of a hardware which uses repetitive hardware components and assume that you have input bit comparators and these bit comparators will then be stacked 8 of them so that we have to use a generic to describe 8 of them and then we have 3 outputs from each bit comparator when you compare the 2 single bits if the result less than equal to or greater than and then we stack these end to end to form a byte comparator notice that the most significant bit is compared closest to the output because if the most significant bit produces a greater than or less than result then the output is independent of the rest of the bits and can appear immediately at the output. So now you have this architecture compose of byte comparator byte comparator is and then we declare a component bit part with these ports and these outputs greater than in equal in and less than in as the inputs because you are concatenating design and greater than out equal out and less than out as output. So each bit comparator has a and b as inputs but it also has concatenating inputs from the previous comparator and it produces 3 outputs which is greater than equal or less than as outputs. So this declares the component and then we say that for all bit part use entity bit compare behavior. So hopefully we have already declared an entity called bit compare which has an architecture behavior and now we declare a signal called connect which will connect all these bit comparator 1 to the other. So essentially these 3 will occur between each repetitive components. So we declare connect as a bi-directional bi-dimensional array. So it is array 1 to 3 because of these 3 signals and 0 to 6 for all these where these 3 group of 3 is to be repeated of STDU logic. STDU logic is a bit type signal which we have not yet done but we could start using it here. This is a type that we have declared remember this is a type. So type connect is an 2 dimensional array and now we say signal cascade is connect that means cascade is a special signal which is a 2 dimensional array of STDU logic which is like type bit. So it is a 2 dimensional array of 3 by 6 3 by 7 actually 0 to 6 of STDU logic and this is the example that we wanted to show. Then we will say for i in 0 to 7 this is going for all the bits generate and then we have a special case if i equal to 0 generate component bit part and when we map it in case of i equal to 0 we map it to the port entries the 0 part maps directly to the entries of the entity and the outputs are a i b i these are the these are the other 2 bit inputs and the outputs are connect 1 i 2 i and 3 i is the bit number which will go from 0 to 7 and generate notice connect is a 2 dimensional array and here 1 2 and 3 are being mapped to the corresponding greater than in equivalent and less than in signals and generate. Also the last part is unique if i equal to 7 then generate and it is very similar except that the inputs are now cascaded but the outputs are the port outputs and the this is the interesting part this is the middle part and if i is greater than 0 and i less than 7 then no port signals are involved and then we say generate and then we say that the component to be used is the bit part and the port mapping is the array at the input and the array at the output only a i and b i are the bit specific signals which will come. So, by using a generate then we have used all the component parts. So, this gives an illustration of how we can use hardware we can describe hardware structurally using components using entity architecture pairs directly and with or without repetition statements we bring this lecture to a close here and then we will wrap up this series on hardware descriptions by describing how behavioral descriptions can be done in VHDL we stop this lecture here.


Money and budgeting. In Australia, you will have to manage your own money. This can be quite challenging. You will need to budget so you can pay for rent, food, bills, clothes, transport, medical expenses, and more. Central Link. Central Link can help you with some income until you earn enough money to support yourself and your family. In return, you will have to work towards finding a job. People are entitled to different payments or allowances depending on their circumstances. This includes people with families, people who are too old or sick to work, and people who are studying, looking for work, or caring for someone. There are a number of different types of concessions and services including childcare benefits, rent assistance, and healthcare cards. Central Link can also help you pay for your rent and bills by using Centre Pay, a free direct bill paying service. Paul Creedon works for Central Link. Everybody has to follow certain rules to receive a Central Link payment. 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Managing your money can be challenging, but if you follow some simple savings advice, your money will last longer. If you have problems managing your money, accessing your bank account or understanding your Centrelink payments, ask for advice. Did you know that most shops will sell certain products at reduced prices? Look out for the sale, reduced or special signs.


Live from Orlando, Florida, it's theCUBE. Covering Accelerate 19, brought to you by Fortinet. Welcome to theCUBE's coverage of Fortinet Accelerate 2019. Live from Orlando, Florida, I'm Lisa Martin with Peter Burris. Peter, it's great to be with you. Our third year co-hosting Accelerate together. Indeed, Lisa. So we moved from, they've moved from Vegas to Orlando, hence we did. So we had a little bit of a longer flight to get here. Just came from the keynote session. We were talking about the loud music, kind of getting the energy going. I appreciated that as part of my caffeination energy this morning, but a lot of numbers shared from Fortinet Accelerate. 4,000 or so attendees here today from 40 different countries. They gave a lot of information about how strong their revenue has been, 1.8 billion, up 20% year on year. Lots of customers added. What were some of the takeaways from you from this morning's keynote session? I think it's, I got three things, I think Lisa. Number one is that you've heard the expression skating to where the puck's going to go. Fortinet is one of those companies that has succeeded in skating to where the puck is going to go. Clearly, cloud is not a architecture or strategy for centralizing computing. It's a strategy for, in a controlled, coherent way, greater distribution of computing, including all the way out to the edge. There's going to be a magnificent number of new kinds of architectures created, but the central feature of all of them is going to be high performance, highly flexible, software-defined networking that has to have security built into it, and Fortinet's at the vanguard of that. The second thing I'd say is that the, we talk a lot about software-defined wide area networking and software-defined networking and software-defined infrastructure, and that's great, but it ultimately has to run on some type of hardware if it's going to work, and one of the advantages of introducing advanced ASICs is that you can boost up the amount of performance that your stuff can run in. And I find it interesting that there's a clear relationship between Fortinet's ability to bring out more powerful hardware and its ability to add additional functionality within its own stack, but also grow the size of its ecosystem. And I think it's going to be very interesting over the next few years to discover where that tension is going to go between having access to more hardware because you've designed it and the whole concept of scale. My guess is that Fortinet's growth and Fortinet's footprint is going to be more than big enough to sustain its hardware so that it can continue to drive that kind of an advantage. And the last thing that I'd say is that the prevalence and centrality of networking within cloud computing ultimately means that there's going to be a broad class of audiences who are going to be paying close attention to it. And in the keynotes this morning, we heard a lot of great talk that was really hitting the network professional and the people that serve that network professional and the security professional. But Fortinet's going to have to expand its conversation out to business people and explain why digital business is inherently a deeply networked structure and also to application developers. Fortinet is talking about how the network and security are going to come together which has a lot of institutional and other implications but ultimately that combination of resources is going to be very attractive to developers in the long run who don't necessarily like security and therefore security has always been a bolt on. So if Fortinet can start attracting developers into that vision and into that fold so the network that combined network security platform becomes more developer friendly we may see some fascinating new classes of applications emerge as a consequence of Fortinet's hardware, market and innovation leadership. One of the things that they talked about this morning was some of the tenants that were discussed at Davos 2019 just 10 weeks ago, they talked about education, ecosystem and technology and then showed a slide, Patrice Perche, the executive senior vice president of sales said, hey, we were talking about this last year, they talked about education and what they're doing to not only address the major skills gap in cybersecurity, what they're doing even to help veterans but from an education perspective rather from an ecosystem perspective this open ecosystem, they talked about this massive expansion of fabric ready partners and technology connector partners as well as of course the technology in which Ken Z, CEO and founder of Fortinet was the speaker at Davos they really talked about sort of hey, last year here we were talking about these three pillars of cybersecurity at the heart of the fourth industrial revolution and look where we are now so they sort of set themselves up as being I wouldn't say predictors of what's happening but certainly at the leading edge and then as you were talking about a minute ago from a competitive perspective talked a lot this morning about where they are positioned in the market against their competitors even down from the number of patents that they have to the number of St. Gartner Magic Quadrants that they've participated in so they clearly are positioning themselves as a leader and from the vibe that I got was a lot of confidence in that competitive positioning. Yeah and I think it's well deserved so you mentioned the skills gap they mentioned, Fortinet mentioned that there's three and a half million more open positions for cybersecurity experts and other people to fulfill it and they're talking about how they're training the NSC's at the rate of about or they're going to have trained 300,000 by the end of the year so they're clearly taking, putting their money where their mouth is on that front. It's interesting that people, all of us tend to talk about AI as a foregone conclusion without recognizing the deep interrelationship between people and technology and how people ultimately will gate the adoption of technology and that's really what's innovations about is how fast you embed it in a business, in a community so that they change their behaviors and so the need for greater cybersecurity numbers of cybersecurity people is going to be a major barrier it's going to be a major constraint on how fast a lot of new technologies get introduced and Fortinet clearly has recognized that as of other network players who are seeing that their total addressable market is going to be shaped strongly in the future by how fast security becomes embedded within the core infrastructure so that more applications, more complex processes, more institutions and businesses can be built in that network. There is one thing I think that we're going to, I think we need to listen to today because the, well, Fortinet has been at the vanguard of a lot of these trends that are having that hardware that opens up additional footprint that they can put more software and software function into there still is a lot of new technology coming in the cloud when we start talking about containers and Kubernetes those are not just going to be technologies that operate at the cluster level they're also going to be embedded down into system software as well so to bring that kind of cloud operating model so that you have, you can just install the software that you need and it's going to be interesting to see how Fortinet over the next few years I don't want to say skinny's up but targets some of its core software functionality so that it becomes more cloud like in how it's managed its implementations how it's updated how fast patches and fixes are handled that's going to be a major source of pressure and a major source of tension in the entire software defined marketplace but especially in the software defined networking marketplace One of the things Kenzie talked about was cloud versus edge and actually said kind of edge will eat the cloud. We have, we live every business lives in this hybrid multi-cloud world with millions of IoT devices and mobile and operational technology that's taking advantage of being connected over IP and from your perspective kind of dig into what Kenzie was talking about with edge eating cloud and companies having to push security out not just I shouldn't say push it out to the edge but as you were saying earlier and they say it needs to be embedded everywhere what are your thoughts on that? Well I think, I would say I had some disagreements with him on some of that but I also think he extended the conversation greatly and the disagreements are mainly kind of nitpicky things so let me explain what I mean by that. The, there's some analysts somewhere some venture capital somewhere that coined the term that the edge is going to eat the cloud and you know that's one of those that's one of those false dichotomies and it's a ridiculous statement there's no reason to say that kind of stuff the edge is going to reshape the cloud the cloud is going to move to the edge the notion of fog computing is ridiculous because you need clarity incredible clarity at the edge and I think that's what Ken was trying to get to the idea that the edge has to be more clear that the same concepts of security the same notions of security discovery, visibility has to be absolutely clear at the edge there can be no fog it must be clear and the cloud is going to move there the cloud operating model is going to move there and networking is absolutely going to be a central feature of how that happens now one of the things that I'm not sure if it was Ken or if it was the pet of products who said it but the notion of the edge becoming defined in part by different zones of trust is I think very very interesting we think at Wikibon we think that there will be this notion of what we call a data zone where we will have edge computing defined by what data needs to be proximate to whatever action is being supported at the edge and it is an action that is the central feature of that but related to that is what trust is required for that action to be competent and by that I mean not only worrying about what resources have access to it but can we actually say that is a competent action that is a trustworthy action that is an that agency that sense of agency is acceptable to the business so this notion of trust as being one of the defining characteristics that differentiates different classes of edge I think is very interesting and very smart and it's going to become one of the key issues that businesses have to think about when they think about their overall edge architectures but to come back to your core point we can call it we can say that the edge is going to going to eat the cloud if we want to I mean who cares I'd rather say that if software is going to eat the world it's going to eat it at the edge and where we put software we need to put trust and we need to put networking that can handle that level of trust and with high performance security in place and I think that's very consistent with what we heard this morning So you brought up AI a minute ago and one of the things that now the keynote is still going on I think there's a panel that's happening right now with their CISO AI is something that we talk about at every event there are many angles to look at AI the good, the bad, the ugly, the in-between I wanted to get your perspective on we talked about the skills gap a minute ago how do you think that companies like Fortinet and other customers in every industry can leverage AI to help mitigate some of the concerns with you mentioned the 3.5 million open positions Well, there's an enormous number of use cases of AI obviously there is AI and machine learning being used to identify patterns of behavior that then can feed a system that has a very, very simple monitor, action, response kind of a interaction kind of a feedback move so that's definitely going to be an important element of how the edge evolves in the future having greater the ability to model more complex environmental issues more complex, you know, intrinsic issues so that you get the right action from some of these devices from some of these sensors from some of these actuators so that's going to be important and even there we still need to make sure that we are appropriately as we talked about defining that trust zone and recognizing that we can't have disconnected security capabilities if we have connected resources and devices the second thing is the whole notion of augmented AI which is the AI being used to limit the number of options that a human being faces as they make a decision so that instead of thinking about AI taking action we instead think of AI or taking action and that's it we think of AI as taking an action limiting the number of options that a person or a group of people face to try to streamline the rate at which the decision and subsequent action could get taken and there too the ability to understand access controls who has visibility into it how we sustain the data how we are able to audit things over time is going to be crucially important now, will that find itself into how networking works? Absolutely because in many network operating centers at least say five, six years ago you'd have a room full of people sitting at computer terminals looking at these enormous screens and watching these events go by and the effort to correlate when there was a problem often took hours and now we can start to see AI being increasingly embedded at the machine learning and other types of algorithms level to try to limit the complexity that a person faces so you can get better response more accurate response and more auditable response to potential problems and Fortinet is clearly taking advantage of that now, the whole FortiGuard labs and their ability to have they've put a lot of devices out there all those devices run very fast they have a little bit of additional performance so they can monitor things a little bit more richly send it back and then do phenomenal analysis on how their customer base is being engaged by good and bad traffic and that leads to Fortinet becoming an active participant not just in an AI level but also at a human being level to help their customers to help shape their customer responses to challenges that are network based and that's a key there that the human interaction because as we know that humans are the biggest security breach starting from basic passwords being one, two, three, four, five, six, seven, eight, nine well Peter- You shouldn't do that. You know, put an exclamation point at the end you'll be fine. Peter and I have a great day coming ahead we've got guests from Fortinet we've got their CEO Kenzie their CISO Phil Quaid is going to be on Derek Mankey with FortiGuard labs talking about the 100 billion events that they're analyzing and helping their customers to use that data we've got customers from Siemens and some of their partners including one of their newest Alliance partners, Symantec so stick around Peter and I will be covering Fortinet Accelerate 19 all day here from Orlando, Florida for Peter Burris I'm Lisa Martin Thanks for watching theCUBE