bit slice chips (was Re: Harris H800 Computer)

Eric Smith spacewar at
Fri Apr 22 19:15:56 CDT 2016

On Thu, Apr 21, 2016 at 12:07 AM, Raymond Wiker <rwiker at> wrote:
> I was a bit surprised to see that it used 2901 with a date code of 1985 -
> the 2901 was introduced 10 years before.

The 2901 was the workhorse bit-slice data path chip for many years.
The A, B, and C suffix parts were progressively faster variants
introduced later. Eventually there were CMOS versions, and 16-bit-wide
versions.  While AMD introduced the 2903 and 29203 as functionally
improved (but not directly compatible) 4-bit parts, they weren't
nearly as widely used as the 2901.

Most other bit-slice parts can be considered "also-ran" at best, with
the Intel 3001 and 3002 probably being the next most successful.  MMI
tried to beat AMD to market with the 5701/6701, which was very similar
to (but not compatible with) the 2901, but they were late to market
and AMD won.

Motorola offered the MC10800 ECL bit slice series, which were
significantly faster at introduction than the contemporary Am2900
parts, but AMD kept introducing faster 2901s.  Some later 2901
variants from AMD and National Semiconductor actually used ECL
internally, but had normal TTL I/O, but the CMOS that followed were
even faster than those.

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