2 ; Ullrich von Bassewitz, 02.04.1999
4 ; unsigned char getcpu (void);
9 ; ---------------------------------------------------------------------------
10 ; Subroutine to detect an 816. Returns
12 ; - carry clear and 0 in A for a NMOS 6502 CPU
13 ; - carry set and 1 in A for a 65C02
14 ; - carry set and 2 in A for a 65816
15 ; - carry set and 3 in A for a 4510
16 ; - carry set and 4 in A for a 65SC02
17 ; - carry set and 5 in A for a 65CE02
18 ; - carry set and 6 in A for a HuC6280
19 ; - carry clear and 7 in A for a 2a03/2a07
21 ; This function uses a $1A opcode which is a INA on the 816 and ignored
22 ; (interpreted as a NOP) on a NMOS 6502. There are several CMOS versions
23 ; of the 6502, but all of them interpret unknown opcodes as NOP so this is
26 .p816 ; Enable 65816 instructions
30 inc a ; .byte $1A ; nop on nmos, inc on every cmos
34 ; This is at least a 65C02, check for a 65CE02/4510
36 .byte $42,$ea ; neg on 65CE02/4510, nop #$ea on 65C02, wdm $ea on 65816
40 ; This is at least a 65CE02, check for 4510
42 lda #5 ; CPU_65CE02 constant
43 .byte $5c ; map on 4510, aug on 65CE02 (acts like 4 byte nop)
44 lda #3 ; CPU_4510 constant
48 ; 6502 type of cpu, check for a 2a03/2a07
50 sed ; set decimal mode, no decimal mode on the 2a03/2a07
53 adc #1 ; $01+$09 = $10 on 6502, $01+$09 = $0a on 2a03/2a07
57 lda #0 ; CPU_6502 constant
60 lda #7 ; CPU_2A0x constant
63 ; 65C02 cpu type, check for HuC6280
64 @L4: ldx #6 ; CPU_HUC6280 constant
65 .byte $22,$ea ; sax nop on HuC6280 (A=$06, X=$01), nop #$ea on 65C02 (A=$01, X=$06)
68 ; Check for 65816/65802
69 @L6: xba ; .byte $eb, put $01 in B accu (nop on 65C02/65SC02)
70 dec a ; .byte $3a, A=$00
71 xba ; .byte $eb, A=$01 if 65816/65802 and A=$00 if 65C02/65SC02
72 inc a ; .byte $1a, A=$02 if 65816/65802 and A=$01 if 65C02/65SC02
81 .byte $f7,$f7 ; nop nop on 65SC02, smb7 $f7 on 65C02
86 lda #4 ; CPU_65SC02 constant
88 @L9: ldx #0 ; Load high byte of word