Re: A86: Sorry about that!
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Re: A86: Sorry about that!
Programs are automatically compatible with shells. The format for
descriptions is below:
nop ; for the title line in shells (ASE)
jp Start ; jump to real start of program
.dw $0000 ; used by shell
.dw ShellTitleText ; pointer to title of the program
ShellTitleText:
.db "Metroid 86 v0.1b",0 ; text in the shell title
Start:
; PROGRAM GOES HERE!
ret
Dan Eble and Bill Nigel tried to come up with a file format for programs
using a special loader, but it never happened. It's at his page. I think
it's a shame they never succeded. The format is neat, and it would have
had support for libraries as well. The file below has the format for
regular TI-86 files:
http://www.ticalc.org/pub/text/calcinfo/ti86prot.txt
Scrolling is done with LDIR and LDDR. I'm not sure if I have the t-states
correct, since I wrote these awhile back:
;================================================================
; Scroll Up:
; Scrolls the screen up by moving the memory
;================================================================
; Current total: 12b/21198t (not counting ret)
;
ScrollUp:
ld hl,$fc10 ; start at top of screen + 16
ld de,$fc00 ; copy starting at top of screen
ld bc,1008 ; copy all but one row (1024 - 16)
ldir ; do the copy
ret ; we're done (wasn't that simple?)
;================================================================
; Scroll Down:
; Scrolls the screen down by moving the memory
;================================================================
; Current total: 12b/21198t (not counting ret)
;
ScrollDown:
ld hl,$ffef ; start at bottom of screen - 16
ld de,$ffff ; copy starting at end of screen
ld bc,1008 ; copy all but one row (1024 - 16)
lddr ; do the copy
ret ; we're done (wasn't that simple?)
At 01:29 AM 8/19/98 -0400, you wrote:
>I do have a couple of questions right now (forgive me if this is
>an obvious one)... Can you do a vertical scroll of the screen using ldir?
>Also: can that go both up and down? or would it only go scroll down
>correctly because of the fact that it decrements the address? Secondly,
>what is necessary to make a program compatible with ASE or Rascall?
>Thirdly, where can i get info on a universal file format for the TI86? I
>heard something about this (possible at Dan Eble's page, if I remember
>correctly) but i didn't know if it was in widespread use yet. Thanks in
>advance Steve Horne
--
David Phillips
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