Intel 80C186EA User Manual page 343

INSTRUCTION SET DESCRIPTIONS
Name
CBW Convert Byte to Word:
CBW
Extends the sign of the byte in register
AL throughout register AH. Use to
produce a double-length (word)
dividend from a byte prior to
performing byte division.
Instruction Operands:
none
CLC Clear Carry flag:
CLC
Zeroes the carry flag (CF) and affects
no other flags. Useful in conjunction
with the rotate through carry left (RCL)
and the rotate through carry right
(RCR) instructions.
Instruction Operands:
none
CLD Clear Direction flag:
CLD
Zeroes the direction flag (DF) causing
the string instructions to auto-
increment the source index (SI) and/or
destination index (DI) registers.
Instruction Operands:
none
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
C-8
Table C-4. Instruction Set (Continued)
Description Operation
if
(AL) < 80H
then
(AH) ← 0
else
(AH) ← FFH
(CF) ← 0
(DF) ← 0
Flags
Affected
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
AF –
ü
CF
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
AF –
CF –
ü
DF
IF –
OF –
PF –
SF –
TF –
ZF –