Practical Electronics CHAMP/Tangerine Microtan 65

From: Dwight K. Elvey <>
Date: Thu May 22 19:46:00 2003

>From: "ben franchuk" <>
>David Comley wrote:
>> Since you mention it, I had been thinking about
>> designing and building a processor from scratch from
>> TTL devices. I am slowly accumulating TTL chips as I
>> come across them at hamfests and things. Perhaps it's
>> time to put pencil to paper.
>> Of course I could take the NASA Apollo Guidance
>> Computer approach and build everything welded-cordwood
>> style out of NOR gates.
>Nope that used lots of REAL ( expensive ) TTL.
>The neat part of that was the CORE memory used.
>Any how a real TTL computer is about 4+ large
>logic cards. Control card, alu card, memory card
>and serial I/O card. The mother board is bus
>and front pannel logic.
>I am doing a 20 bit CPU with about 125 chips total
>in the computer and front panel. About 50?
>more chips for memory and serial i/o.

 All make the assumption that you must make 8 bit/16bit
or, in your case, 20 bit. One can make a 1 bit alu that
can have data width controlled by instruction. It may
not be fast at math but much processor time is consumed
just looking at true/false. If your model doesn't require
passing data through the alu for mem/mem and mem/io moves,
a single bitter makes sense.
 ( My Nicolet is a 20 bit machine. )
Received on Thu May 22 2003 - 19:46:00 BST

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