windows-nt/Source/XPSP1/NT/base/mvdm/dos/v86/inc/chkcpu.inc
2020-09-26 16:20:57 +08:00

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chkcpu macro
jmp begn
msg db 13,10,"This copy of MS-DOS will run only on an 8086",13,10
db "or 8088 CPU based computer. This computer is not ",13,10
db "based on an 8086 or 8088 CPU. ",13,10
db 13,10,"Insert a copy of the appropriate MS-DOS system disk ",13,10
db "and press any key to re-boot.",13,10,0
begn:
;------GET_CPU_TYPE------------------------------------------------------------May, 88 by M.Williamson
; Returns: AX = 0 if 8086 or 8088
; = 1 if 80286
; = 2 if 80386
;
pushf
push bx ; preserve bx
xor bx, bx ; init bx to zero
xor ax,ax ; 0000 into AX
push ax ; put it on the stack...
popf ; ...then shove it into the flags
pushf ; get it back out of the flags...
pop ax ; ...and into ax
and ax,0F000h ; mask off high four bits
cmp ax,0F000h ; was it all 1's?
je scpu_8086 ; aye; it's an 8086 or 8088
mov ax,0F000h ; now try to set the high four bits..
push ax
popf
pushf
pop ax ; ...and see what happens
and ax,0F000h ; any high bits set ?
jz scpu_286 ; nay; it's an 80286
scpu_386: ; bx starts as zero
inc bx ; inc twice if 386
scpu_286: ; just inc once if 286
inc bx
scpu_8086: ; don't inc at all if 086
mov ax, bx ; put CPU type value in ax
pop bx ; restore original bx
popf
cmp ax, 0000
je cpu_ok
push cs
pop ds
mov si, offset msg
prnt: lodsb
or al, al
jz prnt_done
mov ah, 14
mov bx, 7
int 10h
jmp prnt
prnt_done:
xor ah, ah
int 16h
int 19h
cpu_ok:
endm