74ACT158_05 Datasheet, PDF (2/8 Pages) Fairchild Semiconductor – Quad 2-Input Multiplexer

Functional Description
The ACT158 quad 2-input multiplexer selects four bits of
data from two sources under the control of a common
Select input (S) and presents the data in inverted form at
the four outputs. The Enable input (E) is active-LOW. When
E is HIGH, all of the outputs (Z) are forced HIGH regard-
less of all other inputs. The ACT158 is the logic implemen-
tation of a 4-pole, 2-position switch where the position of
the switch is determined by the logic levels supplied to the
Select input.
A common use of the ACT158 is the moving of data from
two groups of registers to four common output busses. The
particular register from which the data comes is determined
by the state of the Select input. A less obvious use is as a
function generator. The ACT158 can generate four func-
tions of two variables with one variable common. This is
useful for implementing gating functions.
Logic Diagram
Truth Table
Inputs
E
S
I₀
H
X
X
L
L
L
L
L
H
L
H
X
L
H
X
H HIGH Voltage Level
L LOW Voltage Level
X Immaterial
Outputs
I₁
Z
X
H
X
H
X
L
L
H
H
L
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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