Does Anyone Have A (smallest gate count computer)

From: Jonathan Engdahl <>
Date: Thu Apr 11 11:42:35 2002

The lowest gate count computer I ever built had two 1 bit accumulators, and
four instructions: AND, NAND, OR, and STORE. It also had a program counter,
a program store, and a data store. The instruction word had a two bit opcode
and a six bit data address. It really was a sort of PLC (programmable logic
controller). I remember the program store was something like eight 2102
RAMs. The rest was maybe a dozen 7400 series TTL chips. I didn't finish the
data store section, but I was able to demonstrate its operation by toggling
in data values by hand as I stepped through the program.

The details are a bit fuzzy. I think it had two 1 bit accumulators, one for
the min-term and one for the sum. AND would load a bit from the data store
and "and" it to the minterm. NAND would do the same except invert the data
first. OR would "or" the minterm into the sum. STORE would save the OR of
the two accumulators to a data location, and preset the minterm accumulator
to 1 and the sum accumulator to 0.

It had no flow control. The PC was simply a 10 bit counter that cycled the
entire program endlessly.

Jonathan Engdahl???????????????? Rockwell Automation
Principal Research Engineer????? 1 Allen-Bradley Drive
Advanced Technology????????????? Mayfield Heights, OH 44124, USA
Mayfield Heights Labs???????????  440-646-7326
-----Original Message-----
[]On Behalf Of John Allain
Sent: Thursday, April 11, 2002 11:04 AM
Subject: Re: Does Anyone Have A
Just in the interest of getting a good sence of the
problem and it's solution, what is the minimum
number of gates necessary to implement a stored
program computer?  I guess the instruction set
would be something like (IF(x=0),JMP,ADD,SUB,MOV)
Was Simon attempting to be this?
John A.
with a few relays kicking around.
Received on Thu Apr 11 2002 - 11:42:35 BST

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