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34 lines
745 B
ArmAsm
34 lines
745 B
ArmAsm
;
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; 2018-04-20, Marco van den Heuvel
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; 2018-04-26, Greg King
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;
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; unsigned char detect_c128 (void);
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;
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;/* Check for the presence of a C128 in C64 mode.
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; *
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; * Possible return values:
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; * 0x00 : C128 in C64 mode not present
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; * 0x01 : C128 in C64 mode present
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; */
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.export _detect_c128
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.include "accelerator.inc"
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_detect_c128:
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ldx #>$0001
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lda #<$0001
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; Make sure the CPU is an 8502.
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.byte $3A ; NOP on 8502, DEA on 65(S)C(E)02, 4510, and 65816
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beq detect_end
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; Make sure a C128 VIC-IIe is present.
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ldy C128_VICIIE_CLK
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cpy #$FF
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bne detect_end
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txa ; return zero when not VIC-IIe
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detect_end:
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rts
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