TI-84 Plus series / Software: There are three different types of programs which can be downloaded or programmed into the calculators: TI-BASIC, Z80 assembly language, and Flash applications (also written in Z80 assembly). In addition, there are programs available that are able to compile or interpret other programming languages. There are a wide range of applications that this produces, from science classes, to games, to calculus to note taking (when put together with a separately sold keyboard). The TI-84 Plus Series is exactly like its predecessor in that it can be used on the SAT and ACT examinations as well as International Baccalaureate examinations. However in some cases those administering the exam may reset the calculator’s memory beforehand to prevent cheating through the use of built in programs or other data.[9] When OS 2.30 was initially released, users noticed the speed of graphing was greatly reduced. The explanation was that the update added asymptote checking in graphing.[10] In January 2006, Texas Instruments released v2.40 of the operating system for the TI-84 Plus series. The most noticeable addition to the new OS was the ”Press-To-Test” feature that allowed a teacher to disable any programs installed on the calculator, so they cannot be used on tests, etc.[11] As of OS version 2.53MP which was released in February 2010, support was added for prettyprinted expressions. However, some programs stopped working correctly in this OS version, or were running slower.[12] The current OS version is 2.55MP which was released in January 2011.[13] In July 2009, a community-made patch now allows user-made operating systems to be easily uploaded onto the TI-84 plus series. Shortly after the patch was developed, the RSA keys for the calculator’s operating system were factored via the General number field sieve (GNFS) algorithm, making a software patch unnecessary. In response to this, Texas Instruments released a newer hardware revision which only accepts other, stronger RSA keys, making it harder to load user-made operating systems or older TI operating systems (2.53MP and earlier). The community has found a way around the newest limitation by discovering a way to revert to older versions of the boot code.[14]