In 1974 Monolithic Memories Inc. (MMI) announced the 6701 bit slice device.  At its heart the 6701 is a 4-bit ALU much like the 74181 TTL IC.  The 6701 adds a register, and some other support circuitry on chip making it much more adaptable.  The 6701 has an approximate complexity of 1000 gates (meaning it would replace 1000 gates worth of TTL).  The 6701 was made on a bipolar process and ran at 5.2MHz.  Later versions would up this speed to around 11MHz.

6701D - 1976

The 6701 continues on until around 1980 by which time the AMD 2901 bit-slice processor had come to completely dominate the market.  The Soviets however cloned/modified the 6701 as the 1802VS1 through the 80′s and into the 1990′s.

In the 1970′s and the 1980′s the Soviets developed and successfully flew their own version of the Space Shuttle.  It was called the Buran.  In many ways it was an enhancements of the US Space Shuttle, based on what the Soviets saw as deficiencies in the US design.  One of the biggest differences was the piloting.  The US STS (Shuttle Transport System) was designed to be a crewed vehicle.  The computers assisted the pilot/co-pilot in launch, orbit, and recovery.  Many of the functions on the STS can be handled by the computers (the Flight Computers were based on the IBM System/4 Pi) but the pilot was needed to handle the rest.  The Soviets, on the other hand, designed the Buran to be able to launch, orbit, and land fully automatically.  This meant the computers has to be very robust, and the programming even more so.  The computers had to respond quickly to chaning inputs, and be able to handle failures gracefully.  While each mission would have a set profile, unknown conditions would cause deviations that the computers must detect, analyse, and properly handle.  Preferably without wrecking the multi-billion ruble space craft.

Buran Computer

The main computer of the Buran is actually 4 independent systems that receive the same inputs.  The clock in generated externally (with 4 backups) so that each computer is in perfect time (the STS uses software to ensure the computers are in time, rather then hardware).  Redundancy is achieved by the voting system. Each computers outputs are compared, if one computers output is different, it is automatically shut down, leaving the 3 remaining computers.  These computers are powered by a clone of the DEC PDP-11.  The Soviet’s ‘acquired’ a few PDP/11 systems and then copied and cloned them into many different systems.  The most common is the 1801 a 5MHz NMOS PDP-11 type device.  The Buran used the 1806, which is the CMOS version.   Here is a general overview of the flight computer.

Angstrem CMOS N1806VM2 - MicroVAX

In addition to the 1806 there were many sub-systems with their own processors.  Details on these are a bit thin, however looking at other Soviet space computer designs it is very likely that many of these used the 134IP3 series of ALUs (a clone of the 54L181 TTL 4-bit ALU).  This chip is also used in the Argon-16 and Argon 16A computers of the Soyuz and Progress spacecraft that are still in use today.  Bit-slice devices were used extensively for many Soviet designs as it gave them a great ability to design custom processors to meet the applications needs.  The Argon-17, which was used for anti-ballistic missile work, was based on the 583 series, an 8-bi slice processor.  The C100 and C101 computers (used as weapons computers on the MiG-29) also use a BSP design.

Xerox Alto-II XM

Just last month an Apple 1 computer sold on eBay for almost $23,000. Today, the father of the PC, and where Steve Jobs got many of his inspirations (as did Bill Gates and numerous other founders of the computer industry), sold on eBay for a bit over $30,000.

The Xerox Alto was really the first modern computer as we know it.  It was developed at the PARC research center, and had Ethernet, a mouse, a GUI, and assorted other things we are rather use to now.  The date? 1973. Xerox did not understand the significance of what they had.  They made over 2000 Altos of various configurations, but never sold them, most were simply given away to friends, workers, and universities.

Though never sold, the Alto’s value in the 1970s was $32,000  or so, not a far cry (disregarding inflation) of what a non-working one just sold for on eBay

The Alto was powered by a custom16-bit bit-slice processor consisting of 4 TTL 74181 ALU’s one of the first uses of the 74181, which was itself the first single chip ALU.

TI SN74S181N - Late 1973 - 90MHz

The 74181 consisted of around 75 gates, and could perform 16 arithmetic functions and 16 logic functions on a pair of 4-bit inputs.  It was, for its time, very fast, much faster then most of the single chip processors of the time.  A 74S181 like shown here, using Schottky technology, could operate at up to 90MHz or so.  Obviously in a computer like the Alto actual clock speed would be reduced to match what the memory could do, which in the Alto, with its 128K of RAM, worked out to 5.8MHz.

Back in the day of CPU’s National was on the forefront of CPU design, while Intel was messing around with 4 and 8 bit designs.  It by itself was the 4th CPU, and the 1st bit slice device. 

It consists of:
4 x 4 bit IMP-00A/520D – These are the Register and Arithmetic Units
1 x IMP16A-521D – Standard 16 bit Instruction set control chip (Based on the Data General Nova)
1 x IMP16A-522D – Extended 16 bit Instruction set (not sure what addition instructions it has)
These were sold in a set by National, and in a pretty nice box.

National IMP16A-500D

Later on National implemented them as a single chip, the IMP16A-500D PACE, and then the NMOS INS8900.
More infomation about the IMP16 can be found at Antique Tech