Western Digital WD4200F-03 – Copy of National COP420 from 1981

In the 1970’s second sourcing was the name of the game.  Processors that had no additional source available often struggled in the market.  Designers wanted to ensure that if they invested in designing a product around a chip, that chip would remain available if the original manufacturer of it had issues.  It also helped drive down pricing, as often second sources could compete on price with the original manufacturer.

By the 1980’s second sourcing had begun to end.  It did still happen, but began to take the form of fabless semiconductor companies today.  A company would create a design and then license its manufacturing to other companies.

National Semiconductor COP420 – 1982

National Semiconductor was a popular second source for many processors of the 1970’s, notably Intel’s 8080, MCS-48 microcontrollers and AMD’s 2901.  For their own designs, they rarely second sourced to anyone.  Such designs as the PACE, SC/MP, original COPS and NSC800 were exclusive to National.  In the 1980’s they did have TI make a very limited amount of 32k processors, likely due to some of the reliability problems National was having in making them themselves early on.  So it is a bit surprising that they licensed the COPS II to Western Digital in the early 1980’s.

Western Digital WD4210BG-15 – Bond out option of the WD4200

The COPS II (later just called COPS) was the 2nd generation COPS 4-bit microcomputer made by National.  It was a NMOS design, designed for basic control oriented applications to replace the PMOS COPs from 1976.  Western Digital already had the 4-bit CR1872 PMOS processor, as well as the CP1611 16-bit design.  Perhaps WD saw the COPS as a filler between those.  It certainly didn’t replace the CR1872, as that design continued to be marketed up until the mid-1980’s.

Western Digital made the WD4200 and WD4210 as copies of the National COP420 and COP421.  Also made was a WD4020 copy of the COP402 (the ROMLESS version used for dev work).  The WD4200 and WD4210 are nearly identical to each other.  The 4200 comes in a 28-pin package while the 4210 came in a 24-pin package.  WD (and National) called this a bond-out option.  The die is the same in both, the 4210 merely has one 4-bit input port left unconnected (IN0-IN3).  A 24-pin package was enough less expensive than a 28-pin package to make this a viable sales option.  Using a bulk NMOS process the die itself was a fairly insignificant cost compared to packaging and testing. The smaller package also was useful for smaller board designs.  The practice continues today with features on processors and MCU’s disabled/enabled to expand a product line and/or make use of die’s with defects.

WD continued to produce the COP line until at least 1983.  Western Digital was moving its focus to the storage market, and away from te general purpose processor/microcomputer market.  This brought an end to the WD4200 as well as WD’s other processors.   Today WD is known for hard drives, and remembered for their disk controllers. that they second sourced a 4-bit design from National has faded to the annuls of history.

CDP180x Test Board

The CPU Shack’s list of test boards continues to grow.  Today we now have available a board for testing RCA COSMAC processors including the CDP1802 1804 1805 and 1806.  These early CMOS processors are still being made 40 years after their introduction in 1975.  Being a CMOS design, the boards are a bit simpler to make (simpler power supplies) and thus a bit less expensive.  They are in stock and shipping now for $89.95.

You can Order them on the RCA180x Test Board page.

Also available are new expansion boards for the MCS-80 boards.  In addition to the Zilog Z80 and Intel 8085 expansions, an expansion is now available for the National Semiconductor NSC800.  Introduced in 1979 this CMOS processor is a hybrid of the Z80 and i8085, taking features of both to greatly enhance the Z80 architecture.

NSC800 Expansion Board

These expansions are available at the same price as the previous ones, $29.95 with FREE Shipping.  They can be ordered from the MCS-80 Expansion page.

Soviet Electronika MK1red3 – F-11 Clone and implementation of PDP-11

The DEC F-11 ‘Fonz’ implementation of the PDP-11 was released in 1979 and was DEC’s second ‘LSI’ implementation of the PDP.  Like its predecessor it was a multi-chip implementation, consisting at its root of a data chip (DC302) and 1-9 control chips (DC303).  The DC303 control chips were essentially a large ROM/PLA with a few extra features added for interrupts and sequencing.  They formed the microcoded instruction set that drove the 16-bit ALU and registers of the DC302.  This is why more then one were supported.  Expanding the instruction set was as ‘simple’ as adding more DC303 chips with these instructions encoded.  The basic LSI11/23 came with one 303 and one 302.  A second IC could be added to support floating point, which included a pair of DC303 chips implementing the floating point instructions.  A MMU (DC304) was also supported, and required when using the FP option.

DEC 570000101A1 F11 Floating Point Option with 2x 303E Control chips

The Soviets also widely adopted the PDP-11 architecture.  Likely because it was designed to be rather hardware independent.  It could be implemented in many different ways, which meant the Soviets could adopt/implement it on their own.  Electronika was part of the Soviet industrial complex in Voronezh, Russia making many different IC’s, but also was tasked with making consumer devices (computers and calculators etc, that were in very short supply.  The Electronika 60 was one of the first PDP-11 computers they made, and it implemented a copy of the DEC Fonz processor.  Electronika combined the standard chipset, and FPU onto a single large MCM with all 4 IC’s (the MMU remained separate) called the MK1 red1 (and later the MK1 red3)

Tetris Electronika 60 – Text Only

KH1811VM1 = DC302 – 21-15541 Data Chip (16-bit ALU etc)
KH1811VU1 = DC303 – 23-001C7 standard instruction set
KH1811VU2 = DC303 – 23-002C7 FP instruction set Part 1
KH1811VU3 = DC303 – 23-003C7 FP instruction set Part 2

It was on this chipset, on a Soviet Electronika 60 that Alexey Pajitnov wrote the very first version of the still famous game of Tetris back in 1984.  A game that was very popular, and very widely copied in the West, even to this day.  (the copying of technology most certainly went both ways)

Sun UltraSPARC TI Marketing Sample

The Sun UltraSPARC IV consumed 105 Watts at 1350 MHz.  This for a dual core processor that could process 2 threads.  Sun decided that the T1 (aka the Niagra) was going to change that.  It was the first ground up redesign of the SPARC core since the UltraSPARC III.  Interestingly Sun originally first attempted to develop a multithreaded process by using a pair of UltraSPARC II cores on a single die.  That project was canceled in 2004, as the T1 was in development.

The T1 was designed to focus on maximum processor utilization.  It contained up to 8 cores, each of which could process 4 threads.  This allows the processor to be used more efficiently, as a single thread can not slow down the entire processor.  All 8 cores share a single Floating Point unit.  This worked well for most database type processing, as FP instructions are not very common in that type of computing.  The T2 (made on a smaller process) allowed for a FP unit for each core which allowed better performance in HPC applications.

Made by TI on a 90nm process, the T1’s 279 million transistors consume only 72 Watts, a 30% reduction from the UltraSPARC IV at a similar clock speed.  This is what Sun called CoolThreads Technology.  Released in November of 2005 Sun was a bit ahead of their time, lower power, more efficient processors were only just beginning to become an important selling point.  Interestingly, its sister project, the UltraSPARC Rk, turned out to be not so cool.  Today, 10 years later, energy efficiency is one of the key metrics when measuring processor performance.  With data centers having on average 50,000 computers, 30 Watts per chip adds up, quick.

TI SN74LS481J -1980 – 8 MHZ 4-bit Slice

The 1970’s was a rush to design new and innovative processors, faster, more features, and more bits.  Most of the processors were new designs, a few were single chip implementations of older mainframes (such as the TMS9900 and the Intersil 6100.  At the same time there was a competition of 4-bit processors.  Somewhat remarkable in 1976 considering 16-bit designs were now being released.  The most famous was of course the AMD AM2901, which undoubtable won the battle.  There were others, the MMI 6701 (a company which AMD would go on to merge with).  Motorola had the MC10800, made in ECL and Intel made the ill-fated (probably since it was only 2-bits) Intel 3002 Processor.  TI made the SBP0400 in I²L that enjoyed some success, but that apparently wasn’t enough.  In 1976, the same year as the SBP0400, the 6701 and the AMD AM2901, TI released the SN74S481.  This was a Schottky TTL 4-bit slice processor (and the SN74S482 sequencer for it).  It was a bit different than its competition.

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The CPU Shack Museum is pleased to announce the availability of Test Board Systems for the Intel 8008 Processor.  This system will allow you to test, as well as design program for, the Intel 8008 8-bit processor as well as its several 2nd sources, including the Siemens SAB8008, the Microsystem International MF8008 and the unlicensed East German MME U808D.

The Test System is loosely based on the 1973 MARK 8 computer, one of the very first computers to use the 8008, which was arguably the worlds first 8-bit processor.

The Boards are available here for $149 with FREE Shipping Worldwide.

16-bit MegaProcessor ALU

James Newman in Cambridge (UK) is creating a 16-bit discrete Processor Design called the Megaprocessor (there is nothing micro about it).  Not a VLSI version either, a 16-bit processor built of discrete transistors, hand wired, hand soldered, with debugging provided by…3500 LEDs.  He admits perhaps things got a bit out of hand when a co-worker remarked that it would be helpful if a signal had an LED on it, thus providing the motivation to go out and build a complete 16-bit processor.

James estimates that the design (he is still building it) will take 14,000 discrete transistors, 3,500 of which are actually to drive the LEDs.  ROM and RAM (256 bytes each, assuming he doesn’t get carpal tunnel from soldering it all) will be an extra 16,000+.

An original Intel 8086 used 29,000 transistors, and was a similar 8/16 bit architecture.  The Novix NC4016 stack processor, also 16-bits, was a very clean design using only 16,000 transistors.  HPs original BPC 16-bit processor from 1975 was 6,000, so James design is certainly inline with expectations (though his sanity maybe in question).

While this seems like a crazy amount of work (it is), This is how the first transistor computers were made.  The original DEC PDP-1 from 1959, used 2,700 discrete transistors, and was an 18-bit design.  The Apollo Guidance computer from 1966 was a 16-bit design (using IC’s with 3 transistors each, so a bit easier construction) used 12,300.

So while James’ design may be a bit over the top, it provides a good look back at where we have come.  Today chips can have well over a billion transistors on a die smaller then a fingernail.

After much delay the 4004/4040 Test Boards are now back in stock.  Only 9 of them so if you need one, order away.

The introduction of the Dallas Semiconductor DS87C520 reaffirms the viability of 8-bit processors for new and demanding applications.  Those were the words written about the the Dallas DS87C520 (and its ROMLess version the DS80C320) in 1994. The Intel MCS-51 architecture it was based on had been released 13 years prior, in 1981 and ran at up to 12MHz.  By 1994 the Pentium had been released, with speeds of up to 100MHz.  Full 64-bit processors were also available, yet the 8-bit processor continued to hold on, and grow.

Dallas Semi. was founded in 1984, by former Mostek employees.  Their first products were lithium battery backed SRAMs, a product pioneered by Mostek.  Dallas added power saving and sensing circuitry to them though, greatly enhancing their usefulness.  In 1987 they combined with with an MCS-51 microcontroller to make the DS5000, which ran at 16MHz and provided battery backed SRAM.

With the release of the DS87C520 in 1994 they redesigned the MCS-51 core, allowing it to complete a machine cycle in 4-clocks vs the original 12.  They were plugin compatible, providing a simple speed up for 8051 systems.  Max clock was also raised, to 33MHz as well as additional interrupts, 16K of EPROM, an extra 1KB of SRAM and many power saving features/modes.  Other companies (such at Philips, and Atmel) began to also make enhanced 8051s, including things such as Flash memory and expanded instructions/features.

Its now 2015, and the 87C520 continues to be made, as does hundreds of other MCS-51.  It was surprising in 1994 that the 8-bit processor continued to be viable, and perhaps to some, even more so, that 21 years later, it is still viable, and shows no signs of slowing down.  The recent push into the Internet-of-Things (IoT) market has 8-bit MCUs in Internet of Things yet again.  While many companies have marked numerous 16-bit and 32-bit designs as ‘a migration path from 8-bit’, that migration is yet to be seen.  There simply is no reason, no need, and no desire to plug a 32-bit processor in where an 8-bit processor, implemented in a few thousand transistors, will do nicely.

Intel MG80386SX16 in a 88-pin PGA

Seeing this pin out, the first processor that comes to mind probably isn’t an Intel 80386.  The 80386DX came in a 132 pin package (PGA or QFP) and the 386SX came in a 100 pin QFP.  The 386SX was the low end version of the 386.  It made do with 16 bits of Data bus, and 24 bits of Address, as opposed to the full 32-bit buses of the DX.  This accounts for 27 less pins (16 Data + 7 Address, 2 data byte selects and a 16/32 bit pin).  That covers all but 6 of the difference in package sizes.  Where are the rest from?  As with most processors, the signaling pins are not the only pins used, or not used on a package.

The 80386DX has 84 signal pins, pins that carry information to or from the processor.  It also has 40 pins for power and ground.  In the early days, when processors had only 40 pins or less, it made sense, and was feasible to have a single power and ground for the entire chip.  As complexities increased, routing became harder, and it became easier to have multiple power and ground pins to the die.  Not to mention electrically more stable, as current requirements were also increasing.  In addition the 386DX has 8 pins not used at all.  These are known as ‘No Connects.’  They are reserved for future use, or were there for testing, or simply just not needed.

Intel 5962-9453301MXA MG80386SX16 – 16MHz 80386SX – 1996 Full Milspec

Moving to the 386SX, which has 26 less signal pins (58), the standard 100 pin package used 10 No Connects and the rest (32) for power and ground.  The pictured 386SX is a late production (1996) military spec processor in an 88 pin package.  88 pins still leave plenty (30 pins) for power, ground, and no connects.  The PGA 386SX was only produced for military/industrial uses.

Why use an expensive PGA package on a low end SX processor?  The reduced bus sizes were plenty for many industrial applications while the ceramic package was much more reliable, and mechanically strong when soldered on to a board then a plastic QFP.  The PGA could work over the entire military specification, for temperature, voltage etc.  Its likely the 386SX could run on an even smaller pin count, but the PGA88 package was a standard package already in production, which often dictates how many pins a processor will have.  The same is true today, pin-count is usually driven more by what works for the package, then what the processor actually strictly needs.