Assembly shell

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On graphing calculators, an assembly shell is a program that is used to run other[ clarification needed ] programs written in the calculator's native machine code rather than the calculator's standard[ clarification needed ] high-level programming language. While all assembly shells can run assembly programs, some can also run high-level programs. For example, MirageOS and DoorsCS, two popular TI-83+ assembly shells, can run TI-BASIC programs by placing a colon as the first bit of code on the first line in the program.

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Assembly shells were created when calculator manufacturers did not support native-code programming. ZShell, [1] the first assembly shell, was created for the TI-85 after an exploit was found using a hacked memory backup file containing the shell to bypass the calculator's standard[ clarification needed ] operating system. Rather than crack down[ clarification needed ] on users who had managed to bypass the OS to run their own code, Texas Instruments chose to release native programming information for its then-upcoming TI-83 calculator. However, their stance changed and they decided to remove native code functionality from the TI-84 plus CE, making an assembly shell necessary once again.

Although this rendered the traditional assembly shell unnecessary on the TI-83 hardware, calculator programmers continued to develop shells to supplement or replace the standard operating system. Since the TI-83, TI has supported assembly-level programming on all subsequent graphing calculators, though similar shell hacks needed to be created for older hardware, such as the TI-82 and the TI-92.

Hewlett-Packard also supports assembly language programming, though onboard[ clarification needed ] programming tools mean that a separate shell is not needed.

See also

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