Truth Table

Output

When

When

Input

When

When

A1 A3 B1 B3 A2 A4 B2 B4 R1 R3 R2 R4C2C4 R1 R3 R2 R4C2C4

LLLL

L

L

L

H

L

L

H

LLL

H

L

L

L

H

L

LHL

L

H

L

L

L

H

L

H

H

L

L

L

H

LH

HL

L

L

H

L

L

H

LH

HL

HLHL

H

H

L

L

L

H

LH

HL

H

H

L

L

L

H

HHH

L

L

L

H

H

L

H

LLL

H

L

H

L

H

H

L

HL

LH

H

H

L

L

L

H

LHLH

H

H

L

L

L

H

H

HLH

L

L

H

H

L

H

LL

H

H

L

L

H

H

L

H

HLH

H

H

L

H

L

H

H

L

HHH

H

L

H

L

H

H

HHHH

L

H

H

H

H

H

Note

Input conditions at A1 B1 A2 B2 and C0 are used to determine outputs R1 and R2 and the value of the

internal carry C2 The values at C2 A3 B3 A4 and B4 are then used to determine outputs R3 R4 and C4

4