March 31st, 2011 ~ by admin

CPU of the Day: MMI 6701 Bit-Slice

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.

February 20th, 2011 ~ by admin

Russian Computers on the Buran Shuttle

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.

Posted in:
Research

February 17th, 2011 ~ by admin

The AMD 2901 Bit Slicer and Second Sourcing

AMD AM2901ADC – 1977

In August 1975 AMD introduced the ‘100 ns Bipolar microprocessor.’ This was a bit-slice device. Essentially a 4-bit ALU (like a 74181) with functionality (scratch pad memory and accumulator register) to make it work as a processor that could be scaled to any bit width (using the 2909 sequencer and 2910 controller).  Being made in bipolar allowed for the high speed (10MHz at the time was pretty quick).  The introduction of the 2901 also marked the beginning of the end to the competition int he bit-slice arena.  A combination of marketing, second-sourcing, and a good product allowed AMD to completely dominate the bit-slice market.  Even today most bit-slice designs are based on the 2901 from 35 years ago.

At the time there were several other bit-slice processors on the market.  Intel had the 3002 (a 2-bit design), National’s IMP-8 and IMP-16, and the original TTL 74181 were all bit-slice devices.  MMI (which AMD bought in the 1980’s) had introduced the 6701 4bit slice in 1974, a full year before AMD’s 2901.  TI had the SBP0400A and Motorola the MC10800 (in ECL – 1976). So why with all this competition did AMD come to dominate?

Raytheon AM2901ADC – 1980

Second Sourcing

Second sourcing is the licensing of a design to other companies for them to manufacture, market and sell it.  Sometimes its simply a license to manufacture, sometimes it comes with technical assistance, or even complete mask sets to make the device.  There are three main reasons this is done (or was done back in the day)

 

Guaranteed Availability.

In the 1970’s making IC’s was a relatively new process, one with many bugs, and often reliability issues.  Having a second source was a must to get a big design win. A system design would not want to design a system around a chip that may end up not being available, or not be available in the quantities needed.  Having a second source to get the IC from alleviated this problem.  It gave system designers a stable supply, regardless if the primary source could not keep up, or had a problem.

 

Distribution

Second-sourcing helped solve distribution problems as well.  A company may have an excellent design, but no way to sell it.  Often this was a geography problem.  American companies did not initially have a large presence, or distributors set up, in Europe or Japan.  An American company would often second-source a design to a European company (such as Siemens or Thomson) solely to get their design distributed in that area.

 

Marketing

One of the keys to a processors success is design wins.  It can be the best processor on the market,. but if no one uses it, it will fail.  Having additional companies make, and market the processor vastly increased its exposure.  Second-source companies would also typically make development systems, and other support tools, as well as vast documentation for the processor.  This helped ensure that engineers knew about the processor, how to use it, and whee to get it, ensuring its winning of more sockets.

Soviet Electronika 1804VS1 – 2901 Clone – 1988

AMD clearly understood the importance of second-sourcing.  In November 1975, just months after the 2901 was released, they designed an agreement with Motorola to make the 2901.  In December, they signed up Raytheon, and in March of 1976 AMD signed an agreement with the SESCOSEM division of Thomson-CSF, to make and distribute the 2901 in markets outside the US and Japan. In June 1976 AMD amended their agreement with Motorola to include more technical assistance, ensuring Motorola could get the 2901 to market. In September 1976 MMI canceled the 6701, as they were unable to compete.  MMI had no second-sources for the 6701 which likely led to its failure.

As the years went by, AMD added more second-sources, and dropped a few. Eventually coming to completely dominate the bit-slice market.  The Soviets began to copy the 2901 around 1985 (not particularly legally but they did what they had to) and continued to do so until well into the 90’s.

Year Second Sources
1975 Motorola
1976 Motorola, Raytheon, Thomson
1977 Motorola, Raytheon, Thomson, National
1978 Motorola, Raytheon, National, Fairchild, NEC, Signetics, Thomson
1980 Motorola, Raytheon, National, Fairchild, NEC, OKI (MSM8821?), Thomson
1982 Motorola (2903), National, Fairchild, NEC, Thomson
1985 National, Thomson, Cypress, USSR
1990 Cypress, IDT, Thomson, National, USSR
1995 Cyrpress, IDT, WSI, Thomson, Russia

Innovasic IA59032 – 8 x 2901 – 2003

AMD also made the AM29C101 which was 4 2901s in a single chip, producing a 16bit processor.  Cypress manufactured a copy of the 29C101 called the CY7C9101

Several other companies also designed multiple 2901s into a single chip. WSI (and later InnovASIC) designed the 59032, which has the equivalent of 8 2901s to form a 32 bit slice and the 59016 which was  16bit slice (4x 2901).  IDT designed the 49C402 which was also a 16 bit slicer.  Today the 2901 is still in wide use, and while not generally used for new designs, it still powers a vast amount of electronic equipment that still is in use.  InnovASIC still manufactures the 2901 (in 59032 form) to this day.

October 18th, 2010 ~ by admin

Before the PC, Before Apple, was the Xerox Alto

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.

Posted in:
Museum News

February 2nd, 2009 ~ by admin

Rare CPU Find of the Day: National Semiconductor IMP16A-500D

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

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