Specifications

MICROPROCESSADORES
CONJUNTO DE INSTRUÇÕES DO 8086
4
Luís Miguel Charrua Figueiredo 4 - 7 E.N.I.D.H.
Rotates the bits in the destination to the right "count"
times with all data pushed out the right side re-entering on
the left. The Carry Flag will contain the value of the last
bit rotated out.
SAHF - Store AH Register into FLAGS
Usage: SAHF
Modifies flags: AF CF PF SF ZF
Transfers bits 0-7 of AH into the Flags Register. This
includes AF, CF, PF, SF and ZF.
SAL/SHL - Shift Arithmetic Left / Shift Logical Left
Usage: SAL dest,count
SHL dest,count
Modifies flags: CF OF PF SF ZF (AF undefined)
70C 0
Shifts the destination left by "count" bits with zeroes
shifted in on right. The Carry Flag contains the last bit
shifted out.
SAR - Shift Arithmetic Right
Usage: SAR dest,count
Modifies flags: CF OF PF SF ZF (AF undefined)
70C
Shifts the destination right by "count" bits with the current
sign bit replicated in the leftmost bit. The Carry Flag
contains the last bit shifted out.
SBB - Subtract with Borrow/Carry
Usage: SBB dest,src
Modifies flags: AF CF OF PF SF ZF
Subtracts the source from the destination, and subtracts 1
extra if the Carry Flag is set. Results are returned in
"dest".
SCAS - Scan String (Byte, Word or Doubleword)
Usage: SCAS string
SCASB
SCASW
Modifies flags: AF CF OF PF SF ZF
Compares value at ES:DI (even if operand is specified)
from the accumulator and sets the flags similar to a
subtraction. DI is incremented/decremented based on the
instruction format (or operand size) and the state of the
Direction Flag. Use with REP prefixes.
SHL - Shift Logical Left
See: SAL
SHR - Shift Logical Right
Usage: SHR dest,count
Modifies flags: CF OF PF SF ZF (AF undefined)
70C0
Shifts the destination right by "count" bits with zeroes
shifted in on the left. The Carry Flag contains the last bit
shifted out.
STC - Set Carry
Usage: STC
Modifies flags: CF
Sets the Carry Flag to 1.
STD - Set Direction Flag
Usage: STD
Modifies flags: DF
Sets the Direction Flag to 1 causing string instructions to
auto-decrement SI and DI instead of auto-increment.
STI - Set Interrupt Flag (Enable Interrupts)
Usage: STI
Modifies flags: IF
Sets the Interrupt Flag to 1, which enables recognition of
all hardware interrupts. If an interrupt is generated by a
hardware device, an End of Interrupt (EOI) must also be
issued to enable other hardware interrupts of the same or
lower priority.
STOS - Store String (Byte, Word or Doubleword)
Usage: STOS dest
STOSB
STOSW
STOSD
Modifies flags: None