76 lines
2.1 KiB
NASM
76 lines
2.1 KiB
NASM
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page 60,132
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title MACHTYPE - MACHINE TYPE CHECKER
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.286c ;; Utilize the expanded 80286 instruction set
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;
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; This routine determines the type of machine we are running on by using the
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; System Services Bios call (INT 15h), Return System Configuration Parms
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; function (AH = C0h). A return code which specifies the machine will be
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; returned via the DOS Terminate function (INT 21h, Func 4ch) as follows:
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;
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; return type machine bios Date
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; ----------- ------- ---------
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;
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; -1 Not a 286/386 machine ----
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; 0 Unknown machine ----
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; 1 IBM PC AT 1/10/84
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; 2 IBM PC AT > 6/10/85
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; 3 IBM PS2 ----
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;
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; The information is used to determine shutdown parameters when switching
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; between protected and real mode by AI Architects OS286 operating environ-
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; ment.
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;
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CODE segment byte public
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assume CS:CODE
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org 100h
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begin:
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jmp start
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start:
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push CS
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pop DS ;; Set up data segment
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mov DX,-1 ;; Default to error condition
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;; See if this is a 286 machine
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mov BX,SP ;; Set up BX with current stack pointer
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pusha ;; 286 instruction, ignored on 808x
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nop ;; Must be after pusha
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cmp BX,SP ;; Were regs pushed?
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je MEMRET ;; No...return with error
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popa ;; Restore regs
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;; Determine machine
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mov dx,0 ;; Default to unknown
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mov ah,0C0h ;; Return system config parameters
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int 15h ;; System services call
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jnc CHK286 ;; jump if carry not set
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mov dx,1 ;; indicate older AT, bios dated 1/10/84
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jmp MEMRET ;; return
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CHK286:
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cmp byte ptr ES:[BX+2],0FCh ;; AT or PS2 model 50 or 60?
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jne CHK386 ;; no, jump
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cmp byte ptr ES:[BX+3],04h ;; Regular AT or PC XT model 286?
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jge GOTPS2 ;; no, see if PS2 Model 80
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mov dx,2 ;; Indicate newer AT, bios dated > 6/10/85
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jmp MEMRET ;; and return
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GOTPS2: mov dx,3 ;; Indicate PS2 model 50 or 60
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jmp MEMRET ;; and return
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CHK386:
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cmp byte ptr ES:[BX+2],0F8h ;; PS2 Model 80?
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jne MEMRET ;; No, return
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mov dx,3 ;; Indicate PS2 model 80
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MEMRET:
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mov AX,DX ;; Return return code
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mov AH,4ch
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int 21h
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CODE ENDS
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END begin
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