Shells are calculator programs that make it easier to setect and run assembly language shells. Some shells, such as Ion, provide the user with a few special routines, which may make a programmers life easier.
What is Ion?
Ion is an Assembly Language Shell for the TI-83 and TI-83 Plus written by Joe Wingbermuehle. Some special features about Ion is that you are able to use routines unique only to Ion! Another good thing about Ion is that programs assembled for Ion will run on both the TI-83 and TI-83 Plus. This tutorial will show you how to make a program that runs under Ion.
Things to Know
Ion is TI-83 Plus Asm. Ion is a shell that runs Asm programs. For Ion to detect an Asm program, it must have the following header at the top of the program. If you look at some very well written Ion games/programs, you will see that there may not be any obvious header. This is okay, as long as the contents is somewhere in there. Ion programs must also use the Ion include file. This is because special Ion routines are located there and using the Ion include file allows the user to assemble the program for the TI-83 and TI-83 Plus. Ion programs also use the bcall() macro to call ROM calls rather than the more familiar B_CALL() macro.
All programs that you want displayed by Ion should have the following header at the beginning of every program:
#include "ion.inc" ;This is the Ion include file that must be used with Ion.
.org progstart-2 ;Program start - 9D95h - As defined in the Ion include file.
.org progstart ;Program start for the TI-83 - 9237h
jr nc,Start ;Jump to start label of program
.db "program name",0 ;This is the name Ion displays
Start: ;Your program begins here
Here is a sample program written for Ion that displays text on the screen:
.db "Display text",0 ;Name of Program
Start: ;Start of the program
bcall(_clrlcdf) ;Clear Screen
bcall(_homeup) ;Bring up the home screen
ld a,0 ;Load 0 to the a register
ld (CURCOL),a ;Load coordinates to CURCOL
bcall(_getkey) ;Wait for keypress
.db "This is the text "
.db "that this prgrm"
.db "will display. "
.db "Each line can be"
.db "16 characters "
.db "long, and can "
.db "only be 7 lines ",0
Assembling Ion programs
Ion programs, unlike TI-OS Asm programs, need to be compiled using Devpac83 and the Asm.bat batch file included with Ion. More information can be found in the Ion documentation included with Ion.
Ion is very useful, especially when it comes to assembling Asm programs compatible with both the TI-83 and TI-83 Plus. More advanced uses of Ion's libraries can be found in Matt Hernandez's IonGuru!
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