mirror of https://github.com/a2-4am/4cade.git
80 lines
2.3 KiB
Plaintext
80 lines
2.3 KiB
Plaintext
;------------------------------------------------------------------------------
|
|
; Has64K
|
|
; Checks whether computer has functioning language card (64K)
|
|
;
|
|
; in: none
|
|
; out: C clear if 64K detected
|
|
; C set if 64K not detected
|
|
; all other flags and registers clobbered
|
|
; ROM in memory (not LC RAM bank)
|
|
;------------------------------------------------------------------------------
|
|
Has64K
|
|
+READ_RAM1_WRITE_RAM1
|
|
lda #$AA ; test #1 for $D0 page
|
|
sta $D000
|
|
eor $D000
|
|
bne @no
|
|
lsr $D000 ; test #2 for $D0 page
|
|
lda #$55
|
|
eor $D000
|
|
bne @no
|
|
clc
|
|
+HIDE_NEXT_BYTE
|
|
@no sec
|
|
+READ_ROM_NO_WRITE
|
|
rts
|
|
|
|
;------------------------------------------------------------------------------
|
|
; Has128K
|
|
; Checks whether computer has functioning auxiliary memory (128K)
|
|
;
|
|
; in: none
|
|
; out: C set if 128K detected
|
|
; C clear if 128K not detected
|
|
; all other flags and registers clobbered
|
|
; zp $80-$9F clobbered
|
|
; ROM in memory (not LC RAM bank)
|
|
;
|
|
; adapted from "Prince of Persia" by Jordan Mechner
|
|
; (c) 1989 Broderbund Software
|
|
; https://github.com/jmechner/Prince-of-Persia-Apple-II/blob/master/01%20POP%20Source/Source/BOOT.S#L119
|
|
;------------------------------------------------------------------------------
|
|
Has128K
|
|
+READ_ROM_NO_WRITE
|
|
sta STOREOFF
|
|
lda ROM_MACHINEID
|
|
cmp #$A0
|
|
beq + ; Spectrum ED
|
|
cmp #6
|
|
bne @no ; earlier than //e -> no 128K
|
|
+ lda SLOT3STATUS
|
|
bmi @no ; no 80-column card -> no 128K
|
|
ldx #@checklen
|
|
- lda @checker,x
|
|
sta $80,x
|
|
dex
|
|
bpl -
|
|
jmp $80 ; check if auxmem actually works
|
|
@checker
|
|
lda #$EE
|
|
sta WRITEAUXMEM
|
|
sta READAUXMEM
|
|
sta $0C00
|
|
sta $0800
|
|
lda $0C00
|
|
cmp #$EE
|
|
bne @no
|
|
asl $0C00
|
|
asl
|
|
cmp $0C00
|
|
bne @no
|
|
cmp $0800
|
|
bne @yes
|
|
@no clc
|
|
+HIDE_NEXT_BYTE
|
|
@yes sec
|
|
@finish sta WRITEMAINMEM
|
|
sta READMAINMEM
|
|
rts
|
|
@checklen=*-@checker
|