; Sample.asm
;
; This simple program prints text on screen and waits for key input. 
; After running it, try making some modifications - more interesting text, 
; wait for a special key, etc.
;
; It should work fine, unless I typed something wrong. Be sure you indent the
; indented lines, otherwise it will not compile properly. Always back up the calc
; memory to the computer before running a program!
;
; A link to download TASM for IBM is at the bottom of this page.


#include "TI-85.h"

ProgStart=$80DF             ; Memory location to save the address of the program


.org 0
.db "Sample", 0

Main:
    ROM_CALL(CLEARLCD)

    ld   HL, 3              ; set text cursor position
    ld   (CURSOR_ROW), HL
    ld   HL, 3
    ld   (CURSOR_COL), HL

    ld   HL, (PROGRAM_ADDR) ; get program's memory address
    ld   (ProgStart), HL    ; save address for later
    ld   DE, HelloMessage   ; get difference between address of program, string
    add  HL, DE             ; add to get address of string
    ROM_CALL(D_ZT_STR)      ; print the string

    call GetLoop            ; wait for a keypress

    ld   HL, 4              ; set new text cursor position
    ld   (CURSOR_ROW), HL
    ld   HL, 3
    ld   (CURSOR_COL), HL

    ld   HL, (ProgStart)    ; get address back 
    ld   DE, ByeMessage     ; get difference between address of program, string
    add  HL, DE             ; add to get address of string 
    ROM_CALL(D_ZT_STR)      ; print the string 

    call GetLoop            ; wait for keypress again 
 
    ret                     ; end of program 
        

 
GetLoop:                    ; wait for keypress 
    call GET_KEY 
    or   A 
    jr   z, GetLoop         ; if no key, try again 

    ret                     ; key pressed - go back      




HelloMessage: 
    .db "Hello, world", 0
ByeMessage:
    .db "Bye!", 0



.end

Download TASM

On to the next lesson: Loops using DJNZ.

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