CSEG SEGMENT PARA PUBLIC 'CODE' ;Start CODE segment ASSUME CS:CSEG,DS:CSEG,ES:CSEG,SS:CSEG ;Set by DOS Loader ORG 100H ;COM file format ENTPT: JMP MAIN SUPPORT_MSG DB "This BIOS supports extended keys$" NO_SUP_MSG DB "This BIOS does not support extended keys$" MAIN PROC NEAR XOR AX,AX MOV ES,AX ASSUME ES:NOTHING MOV DX,OFFSET NO_SUP_MSG MOV AH,12H INT 16H CMP AL,BYTE PTR ES:[417H] JNE NO_SUPPORT XOR BYTE PTR ES:[417H],80H MOV AH,12H INT 16H CMP AL,BYTE PTR ES:[417H] JNE NO_SUPPORT MOV DX,OFFSET SUPPORT_MSG NO_SUPPORT: XOR BYTE PTR ES:[417H],80H MOV AH,9 INT 21H MOV AH,4CH ;Terminate program INT 21H ;Thru DOS MAIN ENDP CSEG ENDS IF1 %OUT Pass 1 Complete ELSE %OUT Pass 2 Complete ENDIF END ENTPT