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| 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 |
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