Intel 80C186XL, User Manual

Page: 367 / 405

INSTRUCTION SET DESCRIPTIONS
C-44
STI Set Interrupt-enable Flag:
STI
Sets IF to 1, enabling processor
recognition of maskable interrupt
requests appearing on the INTR line.
Note however, that a pending interrupt
will not actually be recognized until the
instruction following STI has executed.
Instruction Operands:
none
(IF)
←
1 AF –
CF –
DF –
IF
ü
OF –
PF –
SF –
TF –
ZF –
STOS Store (Byte or Word) String:
STOS dest-string
Transfers a byte or word from register
AL or AX to the string element
addressed by DI and updates DI to
point to the next location in the string.
As a repeated operation.
Instruction Operands:
STOS dest-string
STOS (repeat) dest-string
When Source Operand is a Byte:
(DEST)
←
(AL)
if
(DF) = 0
then
(DI)
←
(DI) + DELTA
else
(DI)
←
(DI) – DELTA
When Source Operand is a Word:
(DEST)
←
(AX)
if
(DF) = 0
then
(DI)
←
(DI) + DELTA
else
(DI)
←
(DI) – DELTA
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
Table C-4. Instruction Set (Continued)
Name Description Operation
Flags
Affected
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
ü
the flag is updated after the instruction is executed