Fischer & Porter 53MC5 – The beginning of the Mystery

One day last summer, I was browsing the deep dark corners for processors, a fun, yet dangerous activity.  I happened upon a lot of PCBs from some older industrial automation equipment.  No real information was provided (those buying these boards clearly would already know what they needed).  They did however have a RTC, an EPROM a 16MHz crystal, and a large 84-pin PLCC.  That PLCC was marked as an Intel N60066.  Seeing such a large chip, surrounded by such components almost always means its some sort of processor or microcontroller.  The problem is, there is no known Intel 60066 part.  The chips were all made in the late 80’s and early 90’s and had  1980 and 1985 copyrights.  A 1980 copyright typically screams MCS-51, as that was when it was introduced and nearly all such chips bear an Intel 1980 mark.

Intel N60066

The boards themselves were dated from 1990 all the way to the early 2000’s (I bought a lot of them, another problem I have).  Some had the part number 53MC5 and the logo of Fischer & Porter.  Fischer & Porter has existed since the 1930’s and was a leader in instrumentation.  They were bought by Elsag Bailey Process Automation (EBPA) in 1994 which itself was swallowed up by ABB in 1999.  The boards design was largely unchanged through all of these transitions. Searching for documentation on the 53MC5 part number (its a Loop Controller) didn’t yield details on what the N60066 was unfortunately.  The only thing left to do was to set it on fire…

Unfortunately this is the only way I currently have for opening plastic IC’s (I need to get some DMSO to try apparently).  After some careful work with the torch and some rough cleaning of the resulting die it was readily apparent that this was an MCU of some sort.  The die itself was marked… 1989 60066.  This wasn’t a custom marked standard product, this was a custom product by Intel for this application, a very surprising thing indeed.  Unlike other companies such as Motorola, Intel was not well known for custom designs/ASICs.  This wasn’t their market or business plan.  Intel made products to suit the needs they saw, if that worked for the end user, great, if not, perhaps you could look elsewhere.  They would gladly modify specs/testing of EXISTING parts, such as wider voltage ranges, or different timings, but a complete custom product? Nope, go talk to an ASIC design house.  Its likely Fischer & Porter ordered enough of these to make it worth Intel’s effort.

Knowing this was an MCU and suspecting a MCS-51 further searching revealed the answer, and it came from the most unusual of places.  In 2009 the US NRC (Nuclear Regulatory Commission) determined there was no adequate Probabilistic Risk Assessment (PRA) for Digital systems in their agency, so set about determining how best to calculate risk of digitally controlled systems.  They analyzed a system used to control feedwater in nuclear reactors.  These are critical systems responsible for making sure the reactor is kept with the right amount of cooling water at the right time, failure of course is not an option.  The 53MC5 is what is used for controlling the valves.  In this document we find this nugget:

The controller is an 8051 processor on board an application-specific integrated circuit (ASIC) chip that performs a variety of functions.

Well that certainly helps, it is indeed a custom ASIC based on an 8051.  The report also provided a diagram showing the ASIC system.  This is an 8051 core with RAM/ROM (normal) as well as a Watchdog timer, a PAL, I/O Buffers, and Address Logic.

I sent a couple of these chips to my friend Antoine in France for a proper die shot, which he is quite amazing at.

Intel N60066 die – 8051 core on the left. Die shot by Antoine Bercovici

The 8051 core is on the left of the die, with its RAM/ROM.  A very large PLA occupies the bottom right side of the day.  In the upper right is presumably the external watchdog timer for the ASIC.  The lines crossing the die mostly vertically are a top metal layer used for connecting all the various sections.

The hunt for a new CPU/MCU is part of the thrill of collecting.  The satisfaction of finding out what a mystery chip is can be worth many hours of dead ends in researching it.  Its not common to have to go to the NRC to find the answer though.

Intel C8051-3 – 1981 – Original 3.5u HMOS

That’s not a typo, we’re going to look briefly at the technology processes (rather then the processors themselves)  Intel went through in the first 5 years of the MCS-51 microcontrollers, and the exceedingly confusing nature of the resulting naming.  When the Intel 8051 series was released in 1980 it was made on two different processes.  The 8031/8051 (non-EPROM) were made on the HMOS-I process, a 3.5 micron single poly process.

Intel C8751-8 – 1982 – Orignal 3.5u HMOS-E

The EPROM version, the 8751 was made on an EPROM process, HMOS-E, which was still a 3.5 micron process, but with 2 poly layers.  This resulted in some slight differences in electrical characteristics (not to mention the programming features not needed on the MaskROM and ROMless versions.

Intel 8751H B-2 ENG. SAMPLE – 1985 -HMOSII-E – 2u

Intel then moved to the HMOS-II (Intel Process P414.1) process in 1984.  This was a shrink to 2 microns, and the EPROM version was also shrunk, but again, using a slightly different EPROM process (Intel Process P421.X).  The HMOSII MaskROM and ROMless versions received the suffix AH, ‘A’ denoting a minor update to the architecture, and ‘H’ for the new HMOSII process.  The EPROM version did not see the same updates though, it received EPROM security bit support and was simply called the 8751H.

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Microchip PIC16C62 ENG SAMPLE – 1989

Yesterday Microchip, makers of the PIC line of microcontrollers, announced they were buying Atmel, for a cool $3.56 Billion.  This isn’t entirely surprising considering the ongoing consolidation in the industry, It was only last year that Dialog attempted to purchase Atmel, and before that ON Semiconductor and Microchip. In December of 2015 NXP and Freescale (formerly Motorola Semiconductors) merged, creating one of the largest microelectronics companies.  These mergers do create an interesting result, product mixes that were formerly competitors, end up being marketed side by side.  In the case of NXP and Freescale, NXP marketed many MCS-51 microcontrollers in their 8/16-bit lines, while Freescale of course sold many versions of MC6800 based MCU’s.  These two rivalries have existed since the early 1980’s and likely will continue.  Perhaps the biggest rivalry in MCU though is between Atmel and Microchip.

Atmel EPROM, fab’d by GI in 1986, right before they became Microchip

Microchip was spun off of General Instrument in 1987, but the PIC architecture dates back to 1976, and is still being made in nearly the same form (PIC16C55).  Atmel was started in 1984, first making EPROMs, and then MCS-51 microcontrollers, one of the very first companies to make an 8051 with on die flash memory.  In a bit of a twist of fate, when Atmel started, it was a fabless company, it contracted with several companies to make its EPROMs, including Sanyo, and General Instruments, which as mentioned above, became Microchip.  Atmel also makes APRC processors, and for a time made Motorola products as well (Atmel has a very convoluted history, for more info on this read here and here )

Today the PIC line continues to be popular, with devices for the low end, such as the PIC10/12 all the way to the MIPS based PIC24 on the upper end.  Atmel continues to make 8051 MCUs, but also makes the 8 and 32-bit AVR line, perhaps best known today for its use in Arduino boards.  They also make MCU’s based on the ARM core, a competitor to MIPS, and Atmel’s own AVR32.

Likely to the consternation to many fans of either company, this merger does make sense, more so than ON or Dialog buying Atmel.  While Microchip and Atmel both compete in the same markets, they do so with different architectures.  Product lines are unlikely to change, and overhead saving should free up $$ both for stockholders (yawn) and engineering teams alike. No word has been giving yet on wether Microchip intends to keep the Atmel branding, but perhaps they should, as an AVR MCU with a Microchip logo on it may just prove to be too much for some.

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 C8744-8 Engineering Sample – Early 1983

In 1980 Intel released the MCS-51 family of microcontrollers, a design that would go on to become one of the pillars of the 8-bit MCU market.  Initially the family consisted of the 8051, which included 4KBytes of on-chip ROM (or UV-EPROM in the case of the 8751) and 128 bytes of RAM as well as the 8031 which did not include the ROM, all program memory was off chip.

The 8051 was a wild success with Intel struggling to meet demand.  Intel did not have the fab capacity to produce both the 8051, and the very in demand 8088 (thanks to IBM).  In 1984 Intel opened a new fab in Albuquerque, New Mexico to build other chips, freeing up production space in the California fab for more 8051s.  Even so, an $8 8051 was routinely scalped for over $200 on the grey market and waiting periods of up to a year were common in order to receive orders, with many companies on allocation.  Intel licensed the design to both AMD (who built a fab in Austin to make it) as well as Signetics in an effort to keep up with demand.  The hardest to get part in the industry, was the 8051 from 1983-1984.

P8344 – A ROMLess 8044, so essentially an 8031 + SDLC controller.

So in the midst of this insatiable demand for an MCU that they did not have the capacity to produce, Intel releases the RUPI-44 (Remote Universal Peripheral Interface). The RUPI-44, also known as the 8044, is an 8051 with an additional 64 bytes of RAM and a full serial communication co-processor on die.  Specifically it was an 8051 that handled the SDLC (Synchronous Data Link Control) protocol in hardware.  Intel had an SDLC controller, known as the 8273, but it was limited to 64kbps, the 8044 could handle data transfers of up to 2.4Mbps due to the 8051 core’s high speed and close coupling of the serial controller.

SDLC was developed in 1975 by IBM and was generally used as a way for mainframes to communicate with various peripherals and terminals.  It supports error correction and multi-point, point to point, and loop connections.  In 1979 SDLC was standardized as HDLC (High-Level Data Link Control) which the RUPI-44 also supports.  While popular in the 70’s and 80’s its use has faded out, though it achieved some long lived use in Europe running the Intel derived BITBUS protocol well into the 90’s.

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Space can often be at a premium, especially in embedded design.  The original 8051 microcontroller was about 750 sq mm.  SiLabs new one? yah all of 4mm^2, and has more features, and is faster. It includes I2C and UARTs integrated in hardware, and an onboard 24.5MHz oscillator.

Silicon Labs C8051T606

Source: EE Times