Forgotten PC History

[Philip Belben]

> The 18 pin-per-package limit claims regarding the 4004 and 8008 have 
> been around for a long time, and I think they came from interviews with 
> Intel's founders and/or early employees, but I think they're factually 
> incorrect, at least as commonly stated.
> 
> The 24-pin DIP was very well established by 1968, and was already used 
> by TI at that time.  There were certainly higher pin-count packages at 
> that time also.  I'm not sure about the 40-pin DIP, but in 1969 
> Fairchild was shipping at least one memory chip in a 36-pin DIP, though 
> that particular package never became popular.

I would find it hard to believe that 24-pin and higher dips were 
unavailable.

I have a couple of Sharp calculators from about that date.  I just 
grabbed the nearest (an ELSI-160) and opened it up, to find that the 
four chips have date codes in early 1971 and forty-two (yes, 42) pins 
each in a dual zigzag arrangement.  The pins are spaced at 0.05 inch, 
and alternate pins stick out 0.1 inch further than the rest.  The whole 
is a gold-top ceramic package a little smaller than a 24-pin DIP.

(FWIW at least one of the calculators has edge connectors with a pin 
spacing of 1.25mm.  But the chips are still 0.05", i.e. 1.27mm.  And 
yes, you can tell the difference.  For the early '70s, this is high 
precision stuff!)

> Possibly whatever specific company Intel was contracting with to supply 
> lead frames and ceramic packages didn't yet offer higher pin count 
> packages, but they obviously were available from some vendors since 
> other semiconductor companies like Fairchild and TI were using them.

That makes sense.  I think someone said it already: if the chip was a 
custom job for a lowish-volume contract, Intel wouldn't want to go and 
find a new packaging contractor for it.

Philip.