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cc65/libsrc/c64/acc_detect_c128.s
2018-04-20 12:08:28 -07:00

34 lines
685 B
ArmAsm
Executable File

;
; Marco van den Heuvel, 2018-04-20
;
; unsigned char detect_c128 (void);
;
;/* Check for the presence of a C128 in C64 mode.
; *
; * Possible return values:
; * 0x00 : C128 in C64 mode not present
; * 0x01 : C128 in C64 mode present
; */
.export _detect_c128
.include "accelerator.inc"
_detect_c128:
lda #$00
tax
; Make sure the CPU is a 8502
.byte $1A ; NOP on 8502, INA on 65(S)C(E)02, 4510 and 65816
bne not_found
; Make sure a C128 VICIIe is present
ldy C128_VICIIE_CLK
cpy #$FF
beq not_found
found:
lda #$01
not_found:
rts