Relay computers

From: Pete Turnbull <>
Date: Fri Sep 24 12:30:40 2004

On Sep 24 2004, 15:39, Ade Vickers wrote:
> Additional: Hunting around for a suitable CPU to implement in relays,
> came across the P8 CPU design
> This uses a 74LS181 4-bit ALU, which I reckon would require 149
relays to
> replicate. The only thing that confuzzles me is: what use, exactly,
is a
> 1-input AND? Several of these appear on the 74LS181 schematic...

I've not seen the specific diagram you're referring to, but are you
sure they're not NAND gates? There are a few in the diagram I have. A
1-input NAND is of course an inverter. But otherwise, a 1-input gate
could be used as a buffer (there are some inverters on the LS181 inputs
for that reason) or to equalise the gate delays along some particular
path to match another.

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Fri Sep 24 2004 - 12:30:40 BST

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