User's Manual

THE 80286 INSTRUCTION SET
ADC/ ADD-Integer Addition
Opcode Instruction Clocks Description
10
Ir
ADC eb,rb 2,mem=7 Add with carry byte register into EA byte
11
Ir
ADC eW,rw 2,mem=7 Add with carry word register into EA word
12
Ir
ADC rb,eb 2,mem=7
Add with carry EA byte into byte register
13
Ir
ADC rW,ew 2,mem=7
Add with carry EA word into word register
14
db ADC AL,db
3
Add with carry immediate byte into AL
15
dw
ADC AX,dw
3
Add with carry immediate word into
AX
80
12
db
ADC eb,db 3,mem=7
Add with carry immediate byte into EA byte
81
12
dw ADC eW,dw 3,mem=7
Add with carry immediate word into EA word
83
12
db ADC eW,db 3,mem=7
Add with carry immediate byte into EA word
00
Ir
ADD eb,rb 2,mem=7
Add byte register into EA byte
01
Ir
ADD eW,rw
2,mem=7 Add word register into EA word
02
Ir
ADD rb,eb 2,mem=7
Add EA byte into byte register
03
Ir
ADD rW,ew 2,mem=7
Add EA word into word register
04 db
ADD AL,db
3 Add immediate byte into AL
05
dw ADD AX,dw
3 Add immediate word into AX
80
10
db
ADD eb,db
3,mem=7
Add immediate byte into EA byte
81
10
dw ADD eW,dw 3,mem=7
Add immediate word into EA word
83
10
db
ADD eW,db 3,mem=7
Add immediate byte into EA word
FLAGS MODIFIED
Overflow, sign, zero, auxiliary carry, parity, carry
FLAGS UNDEFINED
None
OPERATION
ADD and ADC perform an integer addition on the two operands. The ADC instruction also adds in
the initial state of the carry flag. The result of the addition goes to the first operand. ADC is usually
executed as part of a multi-byte or multi-word addition operation.
When a byte immediate value
is added to a word operand, the immediate value is first sign-extended.
PROTECTED MODE EXCEPTIONS
#GP(O) if the result is in a non-writable segment. #GP(O) for an illegal memory operand effective
address in the CS, DS, or ES segments; #SS(O) for an illegal address in the SS segment.
REAL ADDRESS MODE EXCEPTIONS
Interrupt 13 for a word operand at offset OFFFFH.
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