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;
; Marco van den Heuvel, 2018-04-27
;
; unsigned char detect_c65 (void);
;
;/* Check for the presence of a C65/C64DX in C64 mode.
; *
; * Possible return values:
; * 0x00 : C65/C64DX in C64 mode not present
; * 0x01 : C65/C64DX in C64 mode present
; */
.export _detect_c65
.include "accelerator.inc"
_detect_c65:
ldy $D000
; Make sure the CPU is not a 65816
clc
.byte $E2,$01 ; NOP #$01 on 6510 and 65(S)C02, LDA $(01,S),Y on 65CE02 and 4510, SEP #$01 on 65816
lda #$00
tax
bcs not_found ; carry will be set on 65816
; Make sure the CPU is not a 6510
.byte $1A ; NOP on 6510, INA on 65(S)C(E)02
beq not_found
txa
; Make sure the CPU is a 65CE02/4510
.byte $A3,$A3 ; NOP NOP on 65(S)C02, LDZ #$A3 on 65CE02 and 4510
.byte $6B ; NOP on 65(S)C02, TZA on 65CE02 and 4510
cmp #$A3
bne not_found
; Switch to VICIII mode and check if $D040 is a mirror of $D000
ldy #C65_VICIII_UNLOCK_1
sty C65_VICIII_KEY
ldy #C65_VICIII_UNLOCK_2
sty C65_VICIII_KEY
cpy $D040
bne found
inc $D000
cpy $D040
bne not_found
found:
lda #$01
not_found:
sty $D000
sta C65_VICIII_KEY
rts
|
