74LS181

名称

Arithmetic Logic Unit

機能

16種類の論理演算と算術演算が可能な ALU ユニット。

ピン配置

ls181.gif (5623 バイト)

動作

Selection Active High Data
M = H
(論理演算)
M = L (算術演算)
S3 S2 S1 S0 Cn = H Cn = L
L L L L F = A F = A F = A Plus 1
L L L H F = A+B F = A+B F = (A+B) Plus 1
L L H L F = AB F = A+B F = (A+B) Plus 1
L L H H F = 0 F = Minus 1 F = Zero
L H L L F = AB F = A Plus AB F = A Plus AB Plus 1
L H L H F = B F = (A+B) Plus AB F = (A+B) Plus AB Plus 1
L H H L F = A^B F = A Minus B Minus 1 F = A Minus B
L H H H F = AB F = AB Minus 1 F = AB
H L L L F = A+B F = A Plus AB F = A Plus AB Plus 1
H L L H F = A^B F = A Plus B F = A Plus B Plus 1
H L H L F = B F = (A+B) Plus AB F = (A+B) Plus AB Plus 1
H L H H F = AB F = AB Minus 1 F = AB
H H L L F = 1 F = A Plus A F = A Plus A Plus 1
H H L H F = A+B F = (A+B) Plus A F = (A+B) Plus A Plus 1
H H H L F = A+B F = (A+B) Plus A F = (A+B) Plus A Plus 1
H H H H F = A F = A Minus 1 F = A

SELECT と M で演算の種類を選択し、4ビットの各種演算を実行する。マイクロコンピュータの CPU 用。A=B 出力は、オープンコレクタタイプ。

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