Programming instructions

74xx
 National Instruments Corporation 6-21 Multisim Component Reference Guide
6.4.41 74xx155 (Dual 2-to-4 Dec/DEMUX)
This device features a dual 1-line-to-4-line demultiplexer with individual strobes and
common binary-address inputs.
Decoder/demultiplexer truth table:
6.4.42 74xx156 (Dual 2-to-4 Dec/DEMUX (OC))
This device contains two 2-to-4 decoders/demultiplexers.
Decoder/demultiplexer truth table:
6.4.43 74xx157 (Quad 2-to-1 Data Sel/MUX)
This device contains inverters and drivers to supply full on-chip data selection to the four
output gates. It presents true data.
A 4-bit word is selected from one of two sources and is routed to the four outputs.
SELECT STROBE DATA OUTPUTS
ABG
C Y0Y1Y2Y3
XX1 X 1111
000 1 0111
010 1 1011
100 1 1101
110 1 1110
XXX 0 1111
SELECT STROBE DATA OUTPUTS
ABG
C Y0Y1Y2Y3
XX1 X 1111
000 1 0111
010 1 1011
100 1 1101
110 1 1110
XXX 0 1111
ComponentRef.book Page 21 Thursday, December 7, 2006 10:12 AM