 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.Assembly shells were created when calculator manufacturers did not support native-code programming.ZShell, 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 operating system.