74HC181 Datasheet, PDF (5/20 Pages) NXP Semiconductors – 4-bit arithmetic logic unit

Philips Semiconductors
4-bit arithmetic logic unit
Product specification
74HC/HCT181
FUNCTION TABLES
MODE SELECT
INPUTS
ACTIVE HIGH INPUTS AND
OUTPUTS
S₃ S₂ S₁ S₀
LOGIC
(M=H)
ARITHMETIC⁽²⁾
(M=L; C_n=H)
L L L LA
A
L L L H A+B
A+B
L L H L AB
A+B
L L H H logical 0 minus 1
L H L L AB
L H L HB
L H H L A⊕B
L H H H AB
A plus AB
(A + B) plus AB
A minus B minus 1
AB minus 1
H L L L A+B
H L L H A⊕B
H L H LB
H L H H AB
A plus AB
A plus B
(A + B) plus AB
AB minus 1
H H L L logical 1 A plus A⁽¹⁾
H H L H A+B
(A + B) plus A
H H H L A+B
(A + B) plus A
H H H HA
A minus 1
Notes to the function tables
1. Each bit is shifted to the next more significant position.
2. Arithmetic operations expressed in 2s complement
notation.
MODE SELECT
INPUTS
ACTIVE LOW INPUTS AND
OUTPUTS
S₃ S₂ S₁ S₀
LOGIC
(M=H)
ARITHMETIC⁽²⁾
(M=L; C_n=L)
L L L LA
A minus 1
L L L H AB
AB minus 1
L L H L A+B
AB minus 1
L L H H logical 1 minus 1
L H L L A+B
L H L HB
L H H L A⊕B
L H H H A+B
A plus (A + B)
AB plus (A + B)
A minus B minus 1
A+B
H L L L AB
H L L H A⊕B
A plus (A + B)
A plus B
H L H LB
AB plus (A + B)
H L H H A+B
A+B
H H L L logical 0 A plus A⁽¹⁾
H H L H AB
AB plus A
H H H L AB
AB plus A
H H H HA
A
Notes to the function tables
1. Each bit is shifted to the next more significant position.
2. Arithmetic operations expressed in 2s complement
notation.
H = HIGH voltage level
L = LOW voltage level
H = HIGH voltage level
L = LOW voltage level
1998 Jun 10
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