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
20 ; - carry set and 8 in A for a 45GS02
22 ; This function uses a $1A opcode which is a INA on the 816 and ignored
23 ; (interpreted as a NOP) on a NMOS 6502. There are several CMOS versions
24 ; of the 6502, but all of them interpret unknown opcodes as NOP so this is
27 .p816 ; Enable 65816 instructions
32 inc a ; .byte $1A ; nop on nmos, inc on every cmos
36 ; This is at least a 65C02, check for a 65CE02/4510
38 .byte $42,$EA ; neg on 65CE02/4510, nop #$EA on 65C02, wdm $EA on 65816
42 ; This is at least a 65CE02, check for 4510
44 lda #5 ; CPU_65CE02 constant
45 ldx #0 ; to make sure MAP doesn't do anything, the upper nybl of X and Z must be clear
46 .byte $5C ; map on 4510, aug on 65CE02 (acts like 4 byte nop)
47 lda #3 ; CPU_4510 constant
52 ; It is either a 4510 (C65) or a 45GS02 (MEGA65)
54 ; 45GS02 supports 32-bit ZP indirect, so use that to check CPU type
55 ; without requiring a functioning MEGA65 hypervisor.
56 ; We setup a read of $200FF, then store a different value in $00FF
57 ; and then re-read $200FF to see if it is unchanged.
59 ; Save the 32-bit ZP pointer and data byte
66 ; Setup 32-bit pointer to $000200FF
75 ; Prefixing LDA ($nn),Z with a NOP uses 32-bit ZP pointer on 45GS02,
76 ; but normal 16-bit ZP pointer on 4510
77 ; (We assume Z=$00, which will be the normal case)
78 nop ; prefix to tell next instruction to be 32-bit ZP
79 .byte $b2,$fb ; LDA ($nn),Z
80 eor #$ff ; change the value
81 sta $ff ; store in $FF
82 ; now try again to load it: If the same, then 45GS02, as $200FF is unchanged
83 nop ; prefix to tell next instruction to be 32-bit ZP
84 .byte $b2,$fb ; LDA ($nn),Z
85 cmp $ff ; does the loaded value match what is in $FF?
86 beq @Is4510 ; matches, so must be a 4510 = C65
87 bne @Is45GS02 ; $200FF and $FF have different values, so must be a MEGA65 45GS02
89 jsr @RestoreGetCPUTemp
90 lda #3 ; CPU_4510 constant
91 ldx #0 ; load high byte of word
95 jsr @RestoreGetCPUTemp
96 lda #8 ; CPU_45GS02 constant
97 ldx #0 ; load high byte of word
101 ; Save the 32-bit ZP pointer and data byte
103 @L11: lda @GetCPUTemp,x
109 ; Temporary storage for the ZP locations we modify above
110 @GetCPUTemp: .byte 0,0,0,0,0
114 ; 6502 type of cpu, check for a 2a03/2a07
116 sed ; set decimal mode, no decimal mode on the 2a03/2a07
119 adc #1 ; $01+$09 = $10 on 6502, $01+$09 = $0A on 2a03/2a07
123 lda #0 ; CPU_6502 constant
126 lda #7 ; CPU_2A0x constant
129 ; 65C02 cpu type, check for HuC6280
131 ldx #6 ; CPU_HUC6280 constant
132 .byte $22,$EA ; sax nop on HuC6280 (A=$06, X=$01), nop #$EA on 65C02 (A=$01, X=$06)
135 ; Check for 65816/65802
137 xba ; .byte $EB, put $01 in B accu (nop on 65C02/65SC02)
138 dec a ; .byte $3A, A=$00
139 xba ; .byte $EB, A=$01 if 65816/65802 and A=$00 if 65C02/65SC02
140 inc a ; .byte $1A, A=$02 if 65816/65802 and A=$01 if 65C02/65SC02
149 .byte $F7,$F7 ; nop nop on 65SC02, smb7 $F7 on 65C02
154 lda #4 ; CPU_65SC02 constant