74157: Difference between revisions
From NESdev Wiki
Jump to navigationJump to search
(function table) |
(→Signal descriptions: reformat) |
||
| Line 17: | Line 17: | ||
{| class="tabular" style="text-align:center;" | {| class="tabular" style="text-align:center;" | ||
! | ! /E !! S !! I0 !! I1 !! style="border-left:3px double" |Y | ||
|- | |- | ||
| H || X || X || X || L | | H || X || X || X || style="border-left:3px double" |L | ||
|- | |- | ||
| L || L || L || X || L | | L || L || L || X || style="border-left:3px double" |L | ||
|- | |- | ||
| L || L || H || X || H | | L || L || H || X || style="border-left:3px double" |H | ||
|- | |- | ||
| L || H || X || L || L | | L || H || X || L || style="border-left:3px double" |L | ||
|- | |- | ||
| L || H || X || H || H | | L || H || X || H || style="border-left:3px double" |H | ||
|} | |} | ||
Latest revision as of 18:09, 16 April 2023
The 74157 (variants 74LS157, 74HC157) is a 74-series logic IC with four 2-input multiplexers sharing a single select line.
74157 Pinout
.--\/--.
S -> |01 16| -- +5V
1I0 -> |02 15| <- /E
1I1 -> |03 14| <- 4I0
1Y <- |04 13| <- 4I1
2I0 -> |05 12| -> 4Y
2I1 -> |06 11| <- 3I0
2Y <- |07 10| <- 3I1
Gnd -- |08 09| -> 3Y
`------'
Signal descriptions
If /E is high, then all 4 Y output pins output as low, otherwise, if S is low, for each set of pins starting with the same number, Y is equal to I0, otherwise, if S is high, then Y is equal to I1.
Function table (L/H/X = low/high/irrelevant):
| /E | S | I0 | I1 | Y |
|---|---|---|---|---|
| H | X | X | X | L |
| L | L | L | X | L |
| L | L | H | X | H |
| L | H | X | L | L |
| L | H | X | H | H |
