Lab 5

Lab 5 : Programming based on block data transfer

OBJECTIVE

To familiar with the use of data transfer instruction set of 8086

PRELAB

Read data transfer instructions and segment registers from textbook in detail.

DATA TRANSFER INSTRUCTIONS

Instructions	Operands	Description
MOV	REG, memory memory, REG REG, REG memory, immediate REG, immediate SREG, memory memory, SREG REG, SREG SREG, REG	Copy operand2 to operand1. The MOV instruction cannot: • Set the value of the CS and IP registers. • Copy value of one segment register to another segment register (should copy to general register first). • Copy immediate value to segment register (should copy to general register first). Algorithm: operand1 = operand2 Ex: Mov AX,BX ;Copy contents of BX to AX Mov si,00h ;load Si with 00h
PUSH	REG SREG memory	Store 16 bit value in the stack. Algorithm: • SP = SP - 2 • SS:[SP] (top of the stack) = operand
POP	REG SREG memory	Get 16 bit value from the stack. Algorithm: Operand = SS : [SP](top of stack) SP = Sp + 2.
XCHG	REG, memory memory, REG REG, REG	Exchange values of two operands. Algorithm: operand1 < - > operand2
IN	AL, im.byte AL, DX AX, im.byte AX, DX	Input from port into AL or AX. Second operand is a port number. If required to access port number over 255 - DX register should be used.
OUT	AL, ibyte AL, DX AX, DX	Output from AL or AX to port. First operand is a port number. If required to access port number over 255 - DX register should be used.
LEA	REG, memory	Load Effective Address. Algorithm: REG = address of memory (offset)
XLAT	No Operands	Translate byte from table. Copy value of memory byte at DS:[BX + unsigned AL] to AL register. Algorithm: AL = DS:[BX + unsigned AL]

EXERCISES

1) An ALP to transfer a given block of data from source memory block to the destination memory block without overlap.

ASSUME CS:CODE, DS:DATA

DATA SEGMENT
    SOURCE DB 10 DUP(?)  ; Source block
    DEST DB 10 DUP(?)    ; Destination block
    COUNT DW 10          ; Number of bytes to transfer
DATA ENDS

CODE SEGMENT
START:
    MOV AX, DATA
    MOV DS, AX
    MOV ES, AX           ; Set ES to point to the same segment as DS

    LEA SI, SOURCE       ; Load effective address of source into SI
    LEA DI, DEST         ; Load effective address of destination into DI
    MOV CX, COUNT        ; Load count into CX for loop

TRANSFER:
    MOV AL, [SI]         ; Move byte from source to AL
    MOV [DI], AL         ; Move byte from AL to destination
    INC SI               ; Increment source index
    INC DI               ; Increment destination index
    LOOP TRANSFER        ; Repeat until CX = 0

    MOV AH, 4CH          ; DOS function: Exit program
    INT 21H              ; DOS interrupt
CODE ENDS
END START

2) An ALP to exchange a block of data located from source to the destination memory locations.

ASSUME CS:CODE, DS:DATA

DATA SEGMENT
    SOURCE DB 10 DUP(?)  ; Source block
    DEST DB 10 DUP(?)    ; Destination block
    COUNT DW 10          ; Number of bytes to exchange
DATA ENDS

CODE SEGMENT
START:
    MOV AX, DATA
    MOV DS, AX
    MOV ES, AX           ; Set ES to point to the same segment as DS

    LEA SI, SOURCE       ; Load effective address of source into SI
    LEA DI, DEST         ; Load effective address of destination into DI
    MOV CX, COUNT        ; Load count into CX for loop

EXCHANGE:
    MOV AL, [SI]         ; Move byte from source to AL
    MOV BL, [DI]         ; Move byte from destination to BL
    MOV [SI], BL         ; Move byte from BL to source
    MOV [DI], AL         ; Move byte from AL to destination
    INC SI               ; Increment source index
    INC DI               ; Increment destination index
    LOOP EXCHANGE        ; Repeat until CX = 0

    MOV AH, 4CH          ; DOS function: Exit program
    INT 21H              ; DOS interrupt
CODE ENDS
END START

Lab 5

Lab 5 : Programming based on block data transfer

OBJECTIVE

To familiar with the use of data transfer instruction set of 8086

PRELAB

Read data transfer instructions and segment registers from textbook in detail.

DATA TRANSFER INSTRUCTIONS

Instructions	Operands	Description
MOV	REG, memory memory, REG REG, REG memory, immediate REG, immediate SREG, memory memory, SREG REG, SREG SREG, REG	Copy operand2 to operand1. The MOV instruction cannot: • Set the value of the CS and IP registers. • Copy value of one segment register to another segment register (should copy to general register first). • Copy immediate value to segment register (should copy to general register first). Algorithm: operand1 = operand2 Ex: Mov AX,BX ;Copy contents of BX to AX Mov si,00h ;load Si with 00h
PUSH	REG SREG memory	Store 16 bit value in the stack. Algorithm: • SP = SP - 2 • SS:[SP] (top of the stack) = operand
POP	REG SREG memory	Get 16 bit value from the stack. Algorithm: Operand = SS : [SP](top of stack) SP = Sp + 2.
XCHG	REG, memory memory, REG REG, REG	Exchange values of two operands. Algorithm: operand1 < - > operand2
IN	AL, im.byte AL, DX AX, im.byte AX, DX	Input from port into AL or AX. Second operand is a port number. If required to access port number over 255 - DX register should be used.
OUT	AL, ibyte AL, DX AX, DX	Output from AL or AX to port. First operand is a port number. If required to access port number over 255 - DX register should be used.
LEA	REG, memory	Load Effective Address. Algorithm: REG = address of memory (offset)
XLAT	No Operands	Translate byte from table. Copy value of memory byte at DS:[BX + unsigned AL] to AL register. Algorithm: AL = DS:[BX + unsigned AL]

EXERCISES

1) An ALP to transfer a given block of data from source memory block to the destination memory block without overlap.

ASSUME CS:CODE, DS:DATA

DATA SEGMENT
    SOURCE DB 10 DUP(?)  ; Source block
    DEST DB 10 DUP(?)    ; Destination block
    COUNT DW 10          ; Number of bytes to transfer
DATA ENDS

CODE SEGMENT
START:
    MOV AX, DATA
    MOV DS, AX
    MOV ES, AX           ; Set ES to point to the same segment as DS

    LEA SI, SOURCE       ; Load effective address of source into SI
    LEA DI, DEST         ; Load effective address of destination into DI
    MOV CX, COUNT        ; Load count into CX for loop

TRANSFER:
    MOV AL, [SI]         ; Move byte from source to AL
    MOV [DI], AL         ; Move byte from AL to destination
    INC SI               ; Increment source index
    INC DI               ; Increment destination index
    LOOP TRANSFER        ; Repeat until CX = 0

    MOV AH, 4CH          ; DOS function: Exit program
    INT 21H              ; DOS interrupt
CODE ENDS
END START

2) An ALP to exchange a block of data located from source to the destination memory locations.

ASSUME CS:CODE, DS:DATA

DATA SEGMENT
    SOURCE DB 10 DUP(?)  ; Source block
    DEST DB 10 DUP(?)    ; Destination block
    COUNT DW 10          ; Number of bytes to exchange
DATA ENDS

CODE SEGMENT
START:
    MOV AX, DATA
    MOV DS, AX
    MOV ES, AX           ; Set ES to point to the same segment as DS

    LEA SI, SOURCE       ; Load effective address of source into SI
    LEA DI, DEST         ; Load effective address of destination into DI
    MOV CX, COUNT        ; Load count into CX for loop

EXCHANGE:
    MOV AL, [SI]         ; Move byte from source to AL
    MOV BL, [DI]         ; Move byte from destination to BL
    MOV [SI], BL         ; Move byte from BL to source
    MOV [DI], AL         ; Move byte from AL to destination
    INC SI               ; Increment source index
    INC DI               ; Increment destination index
    LOOP EXCHANGE        ; Repeat until CX = 0

    MOV AH, 4CH          ; DOS function: Exit program
    INT 21H              ; DOS interrupt
CODE ENDS
END START