bit slice chips (was Re: Harris H800 Computer)

Rob Doyle radioengr at
Sat Apr 23 13:29:46 CDT 2016

On 4/22/2016 11:56 PM, Brent Hilpert wrote:
>> -----Original Message----- From: cctalk
>> [mailto:cctalk-bounces at] On Behalf Of Jecel Assumpcao
>> Jr. Sent: Friday, April 22, 2016 10:54 PM To: General Discussion:
>> On-Topic and Off-Topic Posts Subject: bit slice chips (was Re:
>> Harris H800 Computer)
>> Eric Smith mentioned:
>>> [2901 A, B, and C, CMOS versions] [2903 and 29203] [Intel 3001
>>> and 3002] [MMI 5701/6701] [Motorola MC10800]
>> I'd add the Texas Instruments SN74S481, SN54LS481 and SN74LS481 TTL
>> 4 bit slices. The Schottky version had a 90ns clock cycle and the
>> low power versions 120ns. These were 48 pins chips and didn't have
>> an internal register bank like the 2901. The idea was that you
>> implemented a memory to memory architecture like the TMS9900. ...
> I'd say the 74181 (1970) deserves a mention here. Simpler (no
> register component, ALU only) but it pretty much kicked off the start
> of IC-level bit slicing.
> Adding to Eric's mention of the PDP-6, the HP2116 (1966) did
> board-level bit-slicing (CPU registers, ALU, datapaths on 4 identical
> boards of 4 bits each).

The MC10181 (same thing at the 74181 except implemented in ECL) is used 
by the DEC KL-10 in several places.


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