Treat SHR registers as write-only (#318)

* Treat SHR registers as write-only

* Revert "no VidHD"

This reverts commit dffb3b1cda.
This commit is contained in:
Tom Greene 2020-07-29 22:27:46 -04:00 committed by GitHub
parent 2c3aa275a1
commit 33e8319078
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 6 additions and 21 deletions

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@ -35,18 +35,6 @@
sta zpMachineStatus
sta SETC3ROM
jsr HasVidHDCard ; check for VidHD card (allows super hi-res artwork even on non-IIgs machines)
bcc +
ldy #@VidHDlen
- lda @s_VidHD,y
sta $68A,y
dey
bpl -
@hang2 bmi @hang2
@s_VidHD !scrxor $80,"CANNOT RUN WITH VIDHD"
@VidHDlen=(*-@s_VidHD)-1
+
sta CLRC3ROM
ror zpMachineStatus
lda ROM_MACHINEID

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@ -123,14 +123,12 @@ SHRArtworkCallback
BlankSHR
jsr Home
lda NEWVIDEO ; set GS NEWVIDEO mode to turn on linearize
ora #%01000000 ; can't use TSB here - might not be 65816
lda #%01000001 ; set GS NEWVIDEO mode to turn on linearize
sta NEWVIDEO
sta WRITEAUXMEM ; writes go to auxmem
lda SHADOW ; enable auxmem-to-bank-E1 shadowing on IIgs
and #$F7 ; can't use TRB here - might not be 65816
lda #$00 ; enable auxmem-to-bank-E1 shadowing on IIgs
sta SHADOW
lda #$20 ; clear $2000..$9FFF in auxmem
@ -139,8 +137,7 @@ BlankSHR
sta WRITEMAINMEM ; writes go to main memory
lda NEWVIDEO ; set GS NEWVIDEO mode to turn on SHR mode
ora #%10000001 ; can't use TSB here - might not be 65816
lda #%11000001 ; set GS NEWVIDEO mode to turn on SHR mode
sta NEWVIDEO
rts

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@ -22,11 +22,11 @@ Home
lda MachineStatus
and #SUPPORTS_SHR
beq @noSHR
lda NEWVIDEO
and #%00011111 ; bit 7 = 0 -> IIgs Apple II-compatible video modes
lda #%00000001 ; bit 7 = 0 -> IIgs Apple II-compatible video modes
; bit 6 = 0 -> IIgs 128K memory map is the same as the Apple IIe
; bit 5 = 0 -> IIgs DHGR is color, not monochrome
; bits 0-4 unchanged
; bits 1-4 reserved
; bit 0 = 1 -> disable bank latch
sta NEWVIDEO
lda #$F0
sta TBCOLOR ; white text on black background