Archive for June, 2013

June 16th, 2013 ~ by admin

CPU of the Day: Bell Labs BELLMAC-8 aka the WE212

Western Electric WE212B - BELLMAC-8 Processor

Western Electric WE212B – BELLMAC-8 Processor – 1979

Many great technologies have came out of Bell Labs including the C programming language and UNIX.  Bell Labs was the R&D arm of AT&T and developed most everything in house for AT&T.  Bell was loathe to use any product that was not their own, so when the computing age of the 70s came, it was only natural for them to develop an in-house microprocessor to run their telecom systems.

The first processor Bell developed was the BELLMAC-8 in 1977.  The BELLMAC-8 was a fairly simple 8-bit processor containing over 7000 transistors and made on a 5 micron CMOS process.  It ran at up to 2 MHz at 5V (5V and -5V supplies).  It implemented 40 instructions most taking around 4 cycles to complete.  the MAC-8 used a 8-bit data bus and a 16-bit address bus (capable of addressing up to 64 Kbytes of RAM). The BELLMAC-8 is a register based design



with 16 general purpose 16-bit registers.  These registers are stored off chip in memory and an on chip Register pointer register (rp) contains the address of their beginning location in memory.  One could perform register ‘saves’ for IRQ handling by simply changing the value in the register pointer register (and storing the old value on the stack).

There is not a great amount of information on the BELLMAC-8 as it was intended for use within Bell/AT&T.  It was not designed or intended to be a commercial processor.  It was used (and branded) be Western Electric (which was the production arm of AT&T) in many telecom products.  Despite its wide use, very little documentation exists, at least outside of AT&T.  It is not a processor covered in any of the standard books/catalogs (such as IC Master, Osborne or other period microprocessor selection guides), most likely because it was for Bells use exclusively.  There was a trainer system made for the BELLMAC-8 used to teach engineers how to use the processor.  Most produced BELLMAC-8s are labeled as WE212 (or F-60789 on the trainers) and are found in Western Electric products.  The WE212 came in several 40-pin packages, including a version with a gold lid, and a version with a black ceramic lid.   Western Electric made several versions (though no documentation on the differences).  These included both the WE212C and the WE212B.

Western Electric WE32100 - BELMAC-32 Processor

Western Electric WE32100 – BELMAC-32 Processor

In 1979 Bell released the BELLMAC-4, a microcomputer version of the BELLMAC-8 containing on chip ROM and RAM.  It was made on a 3.5 micron process.  In 1980 Bell announced the BELLMAC-80.  The BELLMAC-80 was made on a 2.5 micron process (using domino logic CMOS) and contained over 150,000 transistors.  It was Bell’s first 32 bit processor (completely skipping over 16 bit designs) and was later renamed the BELLMAC-32.  A product improved version was called the BELLMAC-32A.  Better known as the 32100 and 32200 processors these CPU’s were used well into the 1990’s.  Unlike the mysterious BELLMAC-8 there is some documentation and wider use of the 32100 series of processors.

June 8th, 2013 ~ by admin

CPU of the Day: Fairchild F8 Microprocessor

Mostek MK3850P-3 - F8 Processor - 1977

Mostek MK3850P-3 – F8 Processor – 1977

In September 1974 Fairchild Camera and Instrument’s Fairchild Semiconductor division announced they were throwing their hat into the microcontroller market.  The same Fairchild whom created ‘Silicon Valley’ whom many of the ‘greats’ of the industry originally worked, including Gordon Moore, and Robert Noyce, of Intel fame.   In April 1975 Fairchild began sampling the F8 processor with production quantities available in the fall of 1975.

Fairchild knew the importance of having second sources available and in June 1975 reached an agreement with Mostek to allow Mostek to produce the F8 as well.  The 10 year agreement with Mostek included complete mask set transfers as Mosteks NMOS isoplanar process was completely compatible with Fairchilds.  The agreement also called for continuing development of the F8 processor system, allowing each company to develop F8 products independently of each other as well as together (this is important down the road).

Fairchild 3850PC - 1977

Fairchild 3850PC – 1977

Mostek was able to rapidly produce the F8 system, faster, cheaper, and more reliable than Fairchild.  The F8 introduction price was $130 per unit.  When Mostek began production in 1975 prices were down to $85 per unit.  In February 1976 Mostek lowered prices to $55 per unit ($64 to $28 if you bought more than 100 pieces).  The F8 was also licensed to SGS-Ates of Italy in 1976.

Also in February of 1976 Fairchild signed a agreement with Olympia Werke A.G., a German company, allowing production and sharing of information on the F8 processor.  It also allowed Fairchild (and any of its second sources, including Mostek) to use any of Olympia’s processor technology and products. So why did Fairchild reach such an agreement with Olympia, a relatively small company?  Because General Instruments was suing Fairchild at the time.

AEG Telefunken U3870M - F8 Processor

AEG Telefunken U3870M – F8 Processor

It gets a little messy here but try to follow along. A man named Dr David Chung (head of GI’s microprocessor division) was dispatched to Olympia to pick up some proprietary information on a top secret 8-bit processor Olympia was developing called the C3PF.  GI had an agreement to license this processor technology from Olympia and it was Chung’s job to get the information to make that possible.  Very shortly after Chung’s return from Germany he quit GI.  Who hired him? Fairchild of course.  GI accused Fairchild (and Chung) of using the proprietary information on the C3PF to develop the F8 processor.  By reaching an agreement with Olympia, Fairchild now was legally covered if in fact they HAD used information on the C3PF in the design of the F8.  Unfortunately very little information exists on the C3PF but it is widely believed that it was the basis of the Fairchild F8.  The court case went on into the 1980’s by which time it didn’t really matter.  I was unable to determine who ‘won’ but by production dates of the F8, it didn’t matter one way or another.

So what about the processor?
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