4004 and IC history / was Re: Vintage computer photogallery

[Brent Hilpert]

dwight elvey wrote:
> 
> > 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.
>  One could use 555 directly now days instead of the 9602s.
> These can output the needed voltage swing.

Oh, I have built a plug-in 4201 replacement from 3 4000-series CMOS ICs, so
the equipment is functional (it's just kind of ugly - a daughter board
connected via a 16-pin DIP plug). The clock cycle used is modulo-7 so it's not
quite trivial. One might question the drive capability of the CMOS but it
seems to work well enough, I think when I did it I looked at the phases on the
'scope and they appeared as sharp as with an actual 4201.