TIP: Click on subject to list as thread! ANSI
echo: apple
to: comp.sys.apple2
from: lyricalnanoha
date: 2008-12-25 03:38:04
subject: Coding for IIgs 2 - working on screen memory

Ouch.  Got wedged trying to pull this off, perhaps I'm interpreting the 
hardware wrong.  Looks like it's trying to write in bank 0 instead of bank 
1.  (I'm using the //e way to access bank 1, according to the docs I have, 
rather than trying to go '816 and do it that way, as I don't yet 
understand 65816 mode.)

The way I *wrote* the code, I meant it to leave ][+ space readable while 
making //e space writable.  (It doesn't seem to have done that.)  Whether 
I .org this high or low, it still gets wedged.  (There's nothing 
IIgs-dependent about the code beyond the C029 thing.)

I'm trying to create a memory environment conducive to plotting pixels in 
320x200x16 mode.  The palette approximates EGA.

-uso.

setty:    lda       $C029
           ora       #$80
           sta       $C029
           bit       $C005
           ldy       #32
{at}1:       lda       paltab-1, y
           sta       $9E00, y
           sta       $9E20, y
           sta       $9E40, y
           sta       $9E60, y
           sta       $9E80, y
           sta       $9EA0, y
           sta       $9EC0, y
           sta       $9EE0, y
           sta       $9F00, y
           sta       $9F20, y
           sta       $9F40, y
           sta       $9F60, y
           sta       $9F80, y
           sta       $9FA0, y
           sta       $9FC0, y
           sta       $9FE0, y
           dey
           bne       {at}1
           lda       #$00
           ldy       #$C7
{at}2:       sta       $9D00, y
           dey
           bne       {at}2
           bit       $C004
           rts

paltab:   .byte     $00, $00, $0C, $00, $C0, $00, $CC, $00
           .byte     $00, $0C, $0C, $0C, $70, $0C, $CC, $0C
           .byte     $77, $07, $0F, $00, $F0, $00, $FF, $00
           .byte     $00, $0F, $0F, $0F, $F0, $0F, $FF, $0F
--- SBBSecho 2.12-Win32
* Origin: Derby City Gateway (1:2320/0)
SEEN-BY: 10/1 3 34/999 120/228 123/500 140/1 222/2 226/0 236/150 249/303
SEEN-BY: 250/306 261/20 38 100 1404 1406 1410 1418 266/1413 280/1027 320/119
SEEN-BY: 393/11 396/45 633/260 267 712/848 800/432 801/161 189 2222/700
SEEN-BY: 2320/100 105 200 2905/0
@PATH: 2320/0 100 261/38 633/260 267

SOURCE: echomail via fidonet.ozzmosis.com

Email questions or comments to sysop@ipingthereforeiam.com
All parts of this website painstakingly hand-crafted in the U.S.A.!
IPTIA BBS/MUD/Terminal/Game Server List, © 2025 IPTIA Consulting™.