Re: LZ-Adv: Help with zshell program and crashing
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Mark and/or Esmeralda Lybrand wrote:
> #include "TI-85.H" ;this is the most current version - I think
>
> .org 0 ;Does this tell the calc where the prgm starts?
>
> .db "Graph a point",0
>
> ld a,4
> out (5),a
>
> ROM_CALL(CLEARLCD)
>
> ld a,1 ;these two put a pixel at bit 7
> ld ($FC00), a ;of byte 1 of the video mem
>
> Wait:
>
> call GET_KEY ;I wanted to check the keypad
> cp 0 ;compare the a reg with 0
> JUMP_Z(Wait) ;if zero flag gets set, loop back (no keypress)
>
> ret z ;return to zshell; (I think my problem is here,
> ;but I took this command from another prgm)
> .end
The problem with your program is when you check for a keypress. The
JUMP_Z
jumps if the zero flag is set, if it is not set it continues to the next
instruction. ret z returns if the zero flag is set, but you only reach
this
place if it is not because of the jump instruction. Try replacing ret z
with
ret. If you do this your program will return every time you reach that
line.
The reason you got all the stuff on your display when you pressed a key
is
that the program did not exit at the ret z instrunction, and therefore
just
continued executing random instructions.
The .org 0 tells the assembler to start adress 0.
<pre>
--
_______________________________________
Dines Justesen
Email: dines@post1.com or
c958362@student.dtu.dk
WWW : http://www.gbar.dtu.dk/~c958362/
_______________________________________
</pre>
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