mirror of
https://github.com/cc65/cc65.git
synced 2024-12-23 04:30:10 +00:00
45 lines
926 B
ArmAsm
45 lines
926 B
ArmAsm
;
|
|
; Marco van den Heuvel, 2018-04-14
|
|
;
|
|
|
|
; unsigned char detect_c64dtv (void);
|
|
;
|
|
;/* Check for the presence of the C64DTV.
|
|
; *
|
|
; * Possible return values:
|
|
; * 0x00 : C64DTV not present
|
|
; * 0x01 : C64DTV present
|
|
; */
|
|
|
|
.export _detect_c64dtv
|
|
|
|
.include "accelerator.inc"
|
|
|
|
_detect_c64dtv:
|
|
ldy C64DTV_Extended_Regs
|
|
lda #$00
|
|
ldx $D000
|
|
|
|
; Make sure the CPU is a 6510
|
|
.byte $1A ; NOP on 8502, INA on 65(S)C(E)02, 4510 and 65816
|
|
bne not_found
|
|
lda #$01
|
|
sta C64DTV_Extended_Regs
|
|
|
|
; Check if $D000 is mirrored at $D040
|
|
cpx $D040
|
|
bne found
|
|
inc $D000
|
|
cpx $D040
|
|
bne not_found
|
|
found:
|
|
lda #$01
|
|
.byte $2C
|
|
not_found:
|
|
lda #$00
|
|
stx $D000
|
|
ldx #$00
|
|
sty C64DTV_Extended_Regs
|
|
rts
|
|
|