bit slice chips (was Re: Harris H800 Computer)

Brent Hilpert hilpert at
Sat Apr 23 01:56:04 CDT 2016

> -----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).

More information about the cctech mailing list