4004 and IC history / was Re: Vintage computer photogallery

[Brent Hilpert]

Chuck Guzis wrote:
> 
> On 12 Oct 2007 at 23:02, Brent Hilpert wrote:
> 
> > Can't testify to it's accuracy but one of my favorite quips about the 4004
> > is the reason it had that multiplexed 4-bit bus/machine cycle was to squish
> > it into a 16-pin package because management didn't want to tool up for larger
> > packages.
> 
> Sounds like an urban legend to me.  24-pin packages were around in
> the Intel line then, I believe.  In any case, the 8008 followed suit

Can't remember where I read it, but it seemed plausible for the time the 4004
was being developed (1970), also that it was compounded by management's perceptions
that the 4004 was a little business on the side and not willing to invest much
in it, memory chips still being the focus. On the other hand, I wonder what
packages the original Busicom designs utilised - that Intel would otherwise have
been obligated to produce - one would expect, or typically, they would be larger.
(The 4040 would go to a larger package, of course.)

> with an 18-pin package.  I suspect that multiplexing didn't matter
> much to the overall speed of the thing.

Perhaps not speed as an issue but you were wired into the small family of
chips that understood the highly specific machine/bus cycle, at least
until the 4008/9 came along that broke out the address/data busses.

> While the 8080 wasn't multiplexed, the 8085 was, as was the
> 8086/8088.    I don't think it was thought to matter.