4004 and IC history / was Re: Vintage computer photogallery
dkelvey at hotmail.com
Sat Oct 13 22:59:46 CDT 2007
> From: hilpert at cs.ubc.ca> > Ethan Dicks wrote:> > > >From time to time, I consider building a small 4004 board - nothing> > more complicated than a digital clock, but my lack of examples to> > study in detail always slows me down. I've read over various> > datasheets, but not recently enough to really recall any specifics. I> > happen to have a couple of 4004s already - one plastic, one ceramic> > package, but they came from devices that I didn't have schematics for> > (one digital kitchen scale, one early barcode reader), and don't have> > the original PCBs from to study.> > > > I can't say that a modern 4004 project would be practical, but it sure> > would be neat to watch. I know there were some older bi-polar 4-bit> > PROMs that should still be programmable with 25-year-old programmers,> > but I suppose that it's just easy enough to use modern 8-bit devices> > and ignore 4 of the bits.
The instruction width is 8 bits so that matches. It is just
the data that is 4 bits. There are a number of 4 bit RAMs out
> > I think one essentially has two choices:> > - find a 4008 & 9 to break out the bus and then you can use standard> 8-bit EPROMS (4004 instructions are 8-bits actually). You may still> be screwed for RAM without a 4002 though, as the 4004 is Harvard arch.> and I'm not sure that the 4008/9 bring out the data address space.> > - (re)design some bus muxing logic (4000 series CMOS should interwork)> to deal with the 4004 cycle and use 4 or 8-bit (E)PROMs and RAM.> In other words, recreate the 4001 and 4002 in SSI (or 4008/9 depending> on your perspective).
If you use the 4008/9 chips, you can used regular EPROMs and static
RAMs. No need to be upset at not having 4001's or 4002's.
Of course you'll need to memory map your I/O. I don't recall if the
4008/4009 did I/O separately but it might.
> > (For 4004 stuff it's nice to find equipment with at least the entire digital> portion intact, precisely to avoid having to do the above.)> > (And I forgot to mention the 4201 clock generator (still looking for one)).
I don't think the board in my development system used a 4201. It
seems it just use a few transistors.
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