Specifications

106 Chapter 6—Primitive Devices
Logic Devices
Multiplexer
This is a device that selects one of N data inputs and routes it to a corre-
sponding output line. There can from 1 to 256 outputs, plus an optional
enable input, as long as the total pin count does not exceed the 800–pin
limit.
A typical 8–to–1 multiplexer obeys the following function table, in which
X = Don’t Care:
EN S2 S1 S0 D7 D6 D5 D4 D3 D2 D1 D0 Q0
0 0 0 0 XXXXXXX0 0
0 0 0 0 XXXXXXX1 1
0 0 0 1 XXXXXX0 X0
0 0 0 1 XXXXXX1 X1
0 0 1 0 XXXXX0 XX0
0 0 1 0 XXXXX1 XX1
0 0 1 1 XXXX0 XXX0
0 0 1 1 XXXX1 XXX1
0 1 0 0 XXX0 XXXX0
0 1 0 0 XXX1 XXXX1
0 1 0 1 XX0 XXXXX0
0 1 0 1 XX1 XXXXX1
0 1 1 0 X0 XXXXXX0
0 1 1 0 X1 XXXXXX1
01110XXXXXXX0
01111XXXXXXX1
1 XXXXXXXXXXX1
LW Reference.bk Page 106 Monday, December 15, 2003 5:59 PM