- Assembly shell (graphing calculator)
On
graphing calculator s, an assembly shell is a program that is used to run programs written in the calculator's nativemachine code rather than the calculator's standardhigh-level programming language . Such programs were originally created at a time when calculator manufacturers did not support native-code programming on their hardware; the first, ZShell [ [http://www.ticalc.org/basics/calculators/ti-85.html The ticalc.org TI-85 page includes information on the history and use of ZShell and later, similar software.] ] was created for theTexas Instruments TI-85 calculator after an exploit was found to bypass the calculator's standardoperating system . Rather than crack down 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-upcomingTI-83 calculator; though this rendered the traditional assembly shell unnecessary on the 83 hardware, calculator programmers continued to develop shells to add to 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 on their hardware; however, due to the availability of onboard programming tools, a separate shell is not needed.While all assembly shells can run assembly programs, some (at least on the TI-83 Plus) also have the capability of running
TI-Basic programs.On some calculators, no native support or easily recognized security holes for running assembly programs is provided, so a "hacked" memory backup file containing a shell [News article on Mallard for the TI-73 at ticalc.org [http://www.ticalc.org/archives/news/articles/12/125/125616.html] ] is sent to the calculator.
References
ee also
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MirageOS External links
* [http://www.ticalc.org/ ticalc.org] - An archive of Assembly and Basic programs for TI calculators.
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