Apple-2-Tools/4cade
1
0
Fork 0
mirror of https://github.com/a2-4am/4cade.git synced 2024-12-27 12:30:30 +00:00
Code Issues Projects Releases Wiki Activity

skip playing Pollywog demo on ROM0 or ROM1 IIgs (#625)

Browse Source 
Better fix; just don't play the Pollywog demo on a ROM0 or ROM1 that can't properly display page 2. We can't turn on Alternate Display Mode due to its use of VBL interrupts on these machines. We can detect and turn it on with ROM3, however, where it does not use interrupts.
This commit is contained in:
frankmilliron 2024-07-02 09:59:46 -07:00 committed by GitHub
parent 7011550118
commit 27bd54a589
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
1 changed files with 29 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
src/demo/pollywog.a
View File

@ -9,9 +9,35 @@
!source "src/macros.a"
+GAME_REQUIRES_JOYSTICK
+TEST_TEXT_PAGE_2 ; will look wonky on ROM0/1 Apple //gs
; due to lores page flipping
+ENABLE_ACCEL_LC
lda ROM_MACHINEID ; is already on. ROM0 and ROM1 versions of ADM use
cmp #$06 ; interrupts and can cause hangs, so safer to just
bne ++ ; leave it turned off, especially in ATTRACT/DEMO mode.
sec
jsr $FE1F ; check for IIgs
bcs +++
tya ; GS ID routine returns with ROM version in Y
cmp #0 ; ROM 0?
beq ++
cmp #1 ; ROM 1?
beq ++
lda #$20
sta $0800 ; check if Alternate Display Mode is already on
lda #$FF
jsr ROM_WAIT ; skip a VBL cycle
!cpu 65816
lda $E00800 ; did we shadow copy data to bank $E0?
cmp #$20
beq + ; only call TEXT2COPY if we know it's off
!cpu 6502 ; https://archive.org/details/develop-04_9010_October_1990/page/n51/mode/1up
jsr ROM_TEXT2COPY ; set alternate display mode on IIgs (required for some games)
+ cli ; enable VBL interrupts
jmp +++
++ jmp $100 ; can't play demo on ROM0 or ROM1 Apple IIgs
; due to extensive use of page 2 throughout
+++ +ENABLE_ACCEL_LC
+LOAD_XSINGLE title
+READ_ROM_NO_WRITE