String manipulation instructions in 8086 microprocessor

String is s series of data byte or word available in memory at consecutive locations. It is either referred as byte string or word string. Their memory is always allocated in a sequential order. Instructions used to manipulate strings are called string manipulation instructions.

Following is the table showing the list of string manipulation instructions:

OPCODE	OPERAND	EXPLANATION	EXAMPLE
REP	instruction	repeat the given instruction till CX != 0	REP MOVSB
REPE	instruction	repeat the given instruction while CX = 0	REPE
REPZ	instruction	repeat the given instruction while ZF = 1	REPZ
REPNE	instruction	repeat the given instruction while CX != 0	REPNE
REPNZ	instruction	repeat the given instruction while ZF = 0	REPNZ
MOVSB	none	moves contents of byte given by DS:SI into ES:DI	MOVSB
MOVSW	none	moves contents of word given by DS:SI into ES:DI	MOVSW
MOVD	none	moves contents of double word given by DS:SI into ES:DI	MOVD
LODSB	none	moves the byte at address DS:SI into AL; SI is incr/decr by 1	LODSB
LODSW	none	moves the word at address DS: SI into AX; SI is incr/decr by 2	LODSW
LODSD	none	moves the double word at address DS:SI into EAX; SI is incr/decr by 4	LODSD
STOSB	none	moves contents of AL to byte address given by ES:DI; DI is incr/dec by 1	STOSB
STOSW	none	moves the contents of AX to the word address given by ES:DI; DI is incr/decr by 2	STOSW
STOSD	none	moves contents of EAX to the DOUBLE WORD address given by ES:DI; DI is incr/decr by 4	STOSD
SCASB	none	compares byte at ES:DI with AL and sets flags according to result	SCASB
SCASW	none	compares word at ES:DI with AX and sets flags	SCASW
SCASD	none	compares double word at ES:DI with EAX and sets flags	SCASD
CMPSB	none	compares byte at ES:DI with byte at DS:SI and sets flags	CMPSB
CMPSW	none	compares word at ES:DI with word at DS:SI and sets flags	CMPSW
CMPSD	none	compares double word at ES:DI with double word at DS:SI and sets flags	CMPSD

My Personal Notes

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