13 Oct
2007
13 Oct
'07
9:52 p.m.
From: dkelvey at hotmail.com---snip---
> I don't think the board in my development system used a 4201. It> seems it
just use a few transistors.
Hi
I was almost right. They used a 4 each 9602 one shots and
several transistor to create the voltages needed for the clocks.
Check the section on bitsavers under Intel and MCS4. The
manual has schematics for the board I have. It used descreate
parts to interface 1702A to the 4004 bus.
It did use 4002s for RAM but that isn't necessary if one
doesn't expect to emulate the Busicom.
The 4002s had a status nibble on each line of 16 nibbles.
This is why it had such funny non-power of 2 size.
One could use 555 directly now days instead of the 9602s.
These can output the needed voltage swing.
Dwight
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