[微机实验/TD-PITE] 存储器扩展实验+选做实验

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;; INPUT RULE
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;;    00 == ORDERED
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;;    01 == UNORDERED
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;;    10 == BYTE
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;;    11 == STOP
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SSEG SEGMENT STACK
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  DW 32 DUP(?)
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SSEG ENDS
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CODE SEGMENT
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ASSUME CS:CODE
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START PROC FAR
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  MOV AL, 1001000B ;; INIT 8255
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  MOV DX, 0614H
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  OUT DX, AL
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  MOV AX, 8000H ;; SET START OFFSET
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  MOV DS, AX
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BEGIN_MAIN:
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  CALL FAR PTR READ_KEY
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  CMP BX, 11B
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  JE EXIT
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  CALL FAR PTR WRITE_TO
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  NOP  ;; BREAK POINT HERE
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  JMP BEGIN_MAIN
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EXIT:
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  MOV AX, 4C00H
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  INT 21H
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START ENDP
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READ_KEY PROC FAR
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  MOV DX, 0640H ;; READ FROM 8255
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  IN AL, DX
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  MOV BL, AL  ;; SET BX
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  MOV BH, 00H
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  RET
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READ_KEY ENDP
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;;; PARAM: BX(MODE)
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WRITE_TO PROC FAR
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  MOV SI, BX
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  AND SI, 1B ;; SI = BX & 1 (01 -> 1, 00/10 -> 0)
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  MOV AX, 0H
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  MOV CX, 10H
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LO:
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  CMP BX, 10B
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  JE BM
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  ;; NORMAL MODE
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  MOV [SI], AX
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  JMP POST
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BM:;; BYTE MODE
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  MOV [SI], AL
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  MOV [SI+1], AH
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POST:
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  INC AX
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  INC SI
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  INC SI
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  LOOP BM
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  RET
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WRITE_TO ENDP
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CODE ENDS
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END START