October 7th, 2019 ~ by admin

The Forgotten Ones: RISCy Business of Winbond

Winbond W77E58P-40 – Your typical Winbond MCS-51 MCU

Winbond Electronics was founded in Taiwan back in 1987, and is most widely known for their memory products and system I/O controllers (found on many motherboards of the 1990s).  They also made a wide variety of microcontrollers, mostly based on the Intel MCS-51 core, like many many other companies have and continue to do.  They also made a few 8042 based controllers, typically used as keyboard controllers, and often integrated into their Super I/O chips.  So why do I find myself writing about Winbond, whose product portfolio seems admittedly boring?

It turns out, that once upon a time, Winbond decided to take a journey on a rather ambition path.  Back in the early 1990’s they began work on a 32-bit RISC processor, and not an ARM or MIPS processor that were just starting to become known at the time, but a processor based on the HP PA-RISC architecture. This may seem a odd, but HP, in a shift form their previous architectures, wanted the PA-RISC design to be available to others.  The Precision RISC Organization was formed to market and develop designs using the architecture outside of HP.  HP wanted to move all of their non-x86 systems to a single RISC architecture, and to help it become popular, and well supported, it was to be licensed to others.  This is one of the same reasons that made x86 so dominate in the PC universe.  More platforms running PA-RISC, even of they were not HP, meant more developers writing PA-RISC code, and that mean more software, more support, and a wider user base.  Along with Winbond, Hitachi and OKI also developed PA-RISC controllers.  Winbond’s path was innovative and much different then others, they saw the need for easy development as crucial to their products success, so when they designed their first PA-RISC processor, the W89K, they made it a bit special.

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October 1st, 2019 ~ by admin

The Story of the IBM Pentium 4 64-bit CPU

Introduction

This time we will talk about one unique Intel processor, which did not appear on the retail market and whose reviews you will not find on the Internet. This processor was produced purely by special order for one well-known manufacturer of computer equipment. Also in the framework of this article I will try to assemble one of the most powerful retro-systems with this processor.

From the title of the article, I think many people understand that we will talk about the Socket 478 Intel processor

Most people are familiar with the Socket 478 that replaced Socket 370 at the end of 2001 (we omit Socket 423 due to its short lifespan of less then a year) and allowed the use of single-core, and then with Hyper Threading technology “pseudo-dual” processors that can perform two tasks in parallel. All production Intel processors within Socket 478 were 32-bit, even a couple of representatives from the Pentium Extreme Edition server segment on the «Gallatin» core. But as always there are exceptions. And this exception, or to be more precise, two exceptions, were two models of Pentium 4 processors with the Prescott core, which had 64-bit instructions (EM64T) at their disposal.

Intel Pentium 4 SL7QB 3.2GHz: 64-bits on S478

This pair of processors were commissioned by IBM for its eServer xSeries servers. These processors never hit the retail market and their circulation was not very large, so finding them now is very problematic. It is interesting that the fact that if you want and naturally have the right amount of money, or a large enough order, you can count on a special order of the processor that is needed for the specific needs, with characteristics that will be unique and will not be repeated in standard production products. And it should be noted that not a few such processors have been released, in fact, in the 70’s and early 80’s this was the very purpose of the now ubiquitous ‘sspec.’ Chips with an Sspec (Specification #) were chips that had some specification DIFFERENT from the standard part/datasheet.  A chip WITHOUT a sspec was a standard product.  By the late 1980’s all chips began to receive sspecs as a means of tracking things like revisions, steppings, etc.  I will talk about some a little later.

hat’s how the processor looks through the eyes of the CPU-Z utility. In the “Instructions” field after SSE3, the EM64T proudly shows off! Link to popular CPU-Z Validation.

Special processors made for IBM belonged to the Prescott core and were based on E0 stepping with support for 64-bit instructions, which is not typical for Socket 478! The first 64-bit CPUs for “everyone” appeared only with the arrival of the next LGA775 socket, and even then it wasn’t right away; some Pentium 4 models in LGA775 version were 32-bit. I specifically pointed out that the Pentium 4 Socket 478 model with EM64T support belonged to the E0-stepping, although later the more advanced stepping G1 was released, which did not have such innovations. The first model worked at a frequency of 3.2 GHz and had a SPEC code – SL7QB, the second was slightly faster with a frequency of 3.4 GHz and the SPEC code – SL7Q8.

For the rest, these were the usual «Prescott». But the presence of 64-bit instructions made these processors unique, capable of working with 64-bit operating systems and the same applications, allowing them to do what their 32-bit comrades simply could not do.

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Boards and Systems

September 18th, 2019 ~ by admin

Pardon the Mess…Upgrading PHP – FIXED

Moving The CPU Shack to PHP 7 and it has broken some old legacy code (now why would a museum have old code? ha).  A few things (like the header and the OLD pictures section) are not working, should be fixed soon.

Thanks!

EDIT: Looks like we got it all fixed, if ya notice anything broken/not working let me know

 

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August 28th, 2019 ~ by admin

Sushi Tacos and Lasers: Marking Intel Processors

Intel ink stamp used for marking chips in the 1970’s

In 1987 Intel became the first semiconductor manufacturer to use lasers to mark all component parts, including ceramic packages (they still used ink for some but had the capability and eventually rolled out laser marking to most all of their assembly/test locations).  Conventional ink marking for ceramic packages required a post-mark ink cure time and production yields ranged from 96%-98% before rework.  That percentage may be good on a school exam, but in the production environment, having to rework 2-4% of everything off the line is unacceptable.  It costs resources, money and time that do not go to making profit.

Intel A80387-20B SX024 remarked with a laser

With lasers, however, the cure operation was not needed and yields increased to better then 99.95%.  Lasers were so consistent that marking became a zero rework process and overall productivity increased by 25%.  Throughput also increased significantly (less rework and lasers are faster) and inspection requirements dropped by 95%.  These lasers were originally developed for ceramic packages but found to work well on plastic packages as well.  They also made remarking significantly easier, old markings could be crossed out with the laser and new marking made.  No stencils, pads or masks were needed, the lasers were programmable and very fast.

Intel continues to use laser marking today (as do most manufacturers).  Intel uses laser marking systems from Rofin-Sinar (now owned by Coherent).  These lasers are typically from the PowerLine E line, which are a diode end-pumped Nd: YVO4 (Neodymium doped yttrium vanadate) diode laser.  These are basically a high ends high power version of the diode lasers used in laser pointers.  Intel went with diode lasers as they were faster, and cleaner then CO2

Intel Package marked SUSHI TACO SALAD. Perhaps the technician was getting hungry while trying to dial in the laser settings.

lasers (at the same power levels).  These lasers typically run in the 10-40Watt range.  Most commonly they are a 532nm laser (green light).  In order to achieve the speeds needed, these marking systems are ran in a pulsed mode, 1-200KHz depending on the speed and material being marked.  This allows the laser to run at very high power, for very short pulses.

This of course requires some tuning, essentially simple trial and error to find the right setting for a given material.  Today’s packages are very thin, and marking on the organic substrate (or the silicon die itself) must be done in a way that leaves the markings visible, but does not damage the underlying structure. These markings are often only a few microns deep on silicon and 25 microns on a package, as deeper then th

Motorola PP603 Engineering Sample with ROFIN BAASEL test marking on the die

at is the chips circuitry.

Rofin offers testing and calibration for some of their bigger customers (such as Intel) where they help develop the settings needed.  This results in a lot of ‘oddly’ marked chips.  Companies will ship packages, dies and whatever else needs to be marked to Rofin along with

specifications of the markings (how wide, tall, deep etc) and the systems/settings are worked out to make it workable on the production line.  Anyone that has used a CO2 desktop laser knows they are not the fastest thing around.  An engraving project completion time is measured in minutes.  When marking chips, speed and accuracy are of paramount importance.  Rofin advertises their lasers as such “Our semiconductor marking solutions achieve marking speeds up to 1600 characters/second. Even at a character height of 0.2 mm and line widths of less than 30 µm they still ensure best readability.”

Package with laser settings engraved

Here we have a test chip package from Intel, marked up by Rofin, there is tests of the 3d-Bar code, Lots numbers s-specs and others.  There is also some calibration markings, its useful to engrave the settings used as for the test, as the test.  In this case we see 25k, 650mms and 23.8A.  These are 3 of the fundamental settings for the laser system.  25k is the pulse rate (25KHz) of the laser, 650mms is the speed, or feed rate, 650mm per sec (about 2ft/sec),  thats a relatively slow speed, but probably was one step in the calibration process.  The 23.8A is the current for the laser, in amps.  Its a rather high current compared to say a continuous wave CO2 laser which runs currents in the milliamps, but these are pulsed lasers, so that current is only needed for a fraction of a second.

Marking can also be done on the die itself.  Here we see a sample

Flip chip marking marketing sample by ROFIN SINAR in Tempe, AZ

(probably an actually marketing sample given away to customers) of a flip chip die, with ROFIN SINAR markings on it, and erven their phone number for their location in Tempe, AZ (only a few miles from several fabs in Chandler, AZ (including Intel and Motorola (now NXP)).

As chips become smaller, marking technology continues to evolve with it.  Markings today have become much less about what the consumer sees, and much more about traceability and trackability.  Being able to follow a device through the supply chain, or trace a defective device back to when/where it was produced.  Marking enhancements also play a great role in combating counterfeiting, helping them out of the supply chain.

There is a lot that goes into designing, making, assembling and even marking a computer chip, and often times things that seem the simplest, such as placing marking on a chip, are anything but simple, and just as important as the fabrication of the die itself.

August 14th, 2019 ~ by admin

How to 386 Your AT: Intel Inboard 386/AT

With the release of the 32-bit Intel 386 processor in 1986, owners of IBM PC/XT and AT type systems (8088 and 80286 systems) were left a bit in the dust.  This was a concern (or opportunity) for Intel as well. They designed an upgrade solution at the same time as the 386, to be able to be used in the now obsolete computers.  This was the Intel InBoard 386 series of upgrade cards.

InBoard 386 AT with 1MB of RAM and 80287 FPU Option (very unusualy on a late model Inboard, this one from 1990, but the FPU is from 1986)

The InBoard, as its name implies, was a internal 16-bit ISA card that was used to upgrade these systems.  It included a 386DX processor running at 16MHz, 64K of cache, and (optionally) 1-3MB of additional RAM.  Two version of the board were made: the PC/XT version was designed for 8088 processor based systems, and the AT version was for the 286 systems.  These boards required the removal of the original processor, and then a cable was ran from the old CPU socket, to the the InBoard 386 board.  On system start up the original BIOS booted the system, and loaded the DOS operating system.  The config.sys file would then call on the drivers to load the InBoard 386 specific features.  The original system was essentially unaware of the new processor, instructions were executed by the InBoard transparently.

Flat Ribbon Cable used for connecting the board to the old CPU socket. If the cable could not reach the socket, your system was not compatible. Cable length was restricted by signal timing, rather then the common complaint of Intel being ‘stingy’

Early AT systems used a 6MHz CPU and ISA bus speed, so Intel provided a 8MHz crystal to replace the original on the motherboard. This ensured the ISA bus that the InBoard used to communicate with the original memory and peripherals ran fast enough and did not become such a huge bottle neck.   The base model InBoard did not come with any RAM, it could use your existing system RAM just fine.  Adding RAM, however, was a worthwhile upgrade.  The Board itself supports 1M (36 100ns 256 kbit chips, including parity) and a daughter card could add another 1M or 2M.  This RAM was accessed via the 80386s 32-bit address bus so was much quicker.  It also was a single wait state access.  You could configure the InBoard to backfill (take over for) your existing system RAM, at least down to 256K, so that the computer would only use the first 256K of the slower RAM before moving to the RAM on the InBoard.  If your system had 512K of RAM you would ‘waste’ half of it but at the benefit of much faster access times.  The Inboard 386 had another trick up its sleeve to improve speed…

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June 12th, 2019 ~ by admin

Xeon Overclocking: Making Gallatin Gallop

This article is part of The CPU Shack’s continued partnership with guest author max1024, hailing from Belarus. I have provided some minor edits/tweaks in the translation from Belorussian to English.

If you still remember the times of the Pentium 4 running on Socket 478 with the Northwood, Prescott and Gallatin cores, then you should remember what about these processor cores were different from each other. Northwood was fast like a mountain doe due to a shorter 20-stage pipeline that allowed it to perform many operations very quickly without tremendous losses due to branch mis-predictions etc. , but inferior to Prescott frequency potential in overclocking, which in turn was as strong as a buffalo, due to twice the L2 cache memory(1M vs 512K) and finer tech process (90nm vs 130nm). But like any hoofed animal, it was not agile, to achieve the higher clock speeds its pipeline was extended to 31-stages, resulting in some cases, clock for clock out performing Northwood, But doing so at the expense of much heat.

A separate niche in the food chain was occupied by “Gallatin”, which combined the properties of the two previous iterations, a shorter 20-stage pipeline, with the high clock speed of the Prescott, but in its arsenal it also had a very formidable weapon, which was the presence of an additional L3 cache of 2 MB. The price of ownership of this “beast” was high, and in the literal sense of the word, it was equal, like any other representative of the Extreme Edition series – $ 999. I resisted this extreme processor, choosing  hero from AMD, the FX-51, which I consider to be one of the most outstanding processors of all times and peoples.

Xeon Universal Chip Analyzer by x86.fr

What could be better, cooler or faster? I’ve been looking for an answer to this question for a long time, until I became acquainted with the Intel Xeon server processors on Socket 604 and in particular with processors based on the Prescott 2M core, which have twice the cache size compared to their desktop counterparts and can run on ASUS production boards.

As everybody knows, it is the advanced desktop flagships of both processor manufacturers that originate from the server segment. So from the Opteron’s turned out the AMD Athlon FX-51, and from the Intel Xeon MP – the Pentium Extreme Edition. This parity of events has been preserved until now.

Xeon Gallatin MP

The server representatives of Intel Xeon processors on the Gallatin core are divided into two branches: Xeon MP (Gallatin) and simply Xeon (Gallatin). The differences are in the number of simultaneously supported processors in the system. So Xeon MP supported running up to four processors  usual Xeon could be installed in servers only in pairs. There is also a difference in steppings of the processor core itself. Let me remind you that the desktop version of “Gallatin” were the M0 stepping, just like the regular Intel Xeon series.

The Xeon MP line, by contrast, is based on an earlier stepping from A0 to C0. Among the representatives of M0 stepping, you can find four Xeon models (Gallatin) with 1M of L3 cache, with frequencies from 2.4 GHz to 3.2 GHz, and one model with a doubled  L3 cache to 2 MB, pretty much the same as a Pentium 4 Extreme Edition. This model gave rise to the first “extreme” Pentium.

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June 1st, 2019 ~ by admin

All Boxed up: Retail Boxed CPU’s

NIB MOS 6502 CPU

New In Box MOS MCS6502 CPU from 1975 (Michael Steil – pagetable.com)

Today most all processors are permanently installed in their device (soldered in) or were taken from a bulk tray and installed by the OEM such as Dell or HP.  AMD has, at least with their higher end CPU’s gotten quite creative with the marking on the chip itself, and both AMD and Intel still offer some pretty amazing retail packaging for their enthusiast processors (the i9 in a dodecahedron package is pretty cool).  There was a time when almost all processors were available in retail packaging.  This was the time of physical computer shops, largely bypassed now by the Internet, where the packaging of a processor helped sell it.

I collect such New In Box (NIB) processors as they are pretty need to see the branding/marketing that went with the CPU’s of years past, and was reminded of this when I saw perhaps one of the oldest NIB CPU’s I have ever seen on Michael Steil’s pagetable.com blog.  An original MOS 6502 processor from 1975 in its original shipping box, as close to NIB as one can get.  MOS’s packaging would make Apple proud with its simplicity and design keeping everything tidy and the MCS6502 visible as soon as the box is opened (I am happy they didn’t use miserable black foam either, so the CPU is pristine after 45 years).  Even the original invoice is included.  $25 for the CPU ($118 in 2019 dollars) and $10 (nearly half the cost of the CPU ($47 in 2019)) for documentation)

Cyrix 83D87 386 FPU

Cyrix 83D87 386 FPU Bundled with Borland Quattro PRO Spreadsheet software (a big thing back in 1992)

Intel started offering retail boxed CPUs with the 8087 coprocessor.  This was really the first chip designed as a user upgrade to their PC (a new thing back then).  Before this Intel’s closest thing to a NOB was University Kits or Dev Kits for various chips/processors.  With the introduction of the PC, and the many thousands of beige box clones that followed, people themselves began buying processors and building computers for themselves at a much greater pace then before.  There was many companies making compatible processors at the time so packaging helped set them apart.  This began with upgrade products, math coprocessors for the 808x, 286 and 386 were the most common (by Intel, AMD, IIT, ULSI. Cyrix and more), but eventually processors themselves started getting the NIB treatment, Intel made OverDrive processors (still technically an upgrade product) for the 486. followed by actual Pentium CPUs in the retail box. By the late 1990’s everything from Celerons to Xeon server processors could be had in Retail box.  Buying a retail boxed Xeon for your rackmount server seems like an odd thing to do, but apparently Intel figured it would need to be done.

Quad AMD Opteron 6128s in Retail Box

Quad AMD Opteron 6128s in Retail Box

Other companies such as AMD, Cyrix and VIA made NIB processors but they are much less common, and in a lot of ways more interesting.  AMD made retail Durons, Athlons, and Opterons, and in one of the most unusual things I have seen for a NIB, an actual 4-pack of Opteron 6128s (pictured). The Opteron 6128 is a 8 core Magny-Cours server processor introduced in 2009 and cost $266 each at that time.  This NIB set is dated late 2011, so would probably be a bit cheaper, but still $800 or so, and the large SWATX motherboards needed to run 4 socket G34 processors require somewhat special cases and PSU’s, but at least you can have  a half terabyte of RAM.  Inside the retail box is 4 smaller boxes, each containing an Opteron 6128 CPU, installation instructions, warranty info, and a case badge (you get 4 total case badges).  It seems this packaging was designed to support different configurations (probable a single Opteron 6128, and duals).

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April 18th, 2019 ~ by admin

Tiered up for 3D-FPGAs: The Story of the Tier Logic FPGA-ASIC

100K LUT Tier Logic FPGA TL1F100 on the left and TL1A100 ASIC on the right

This is the CPU Shack Museum, but occasionally I find a chip thats not really a CPU but is of such interest that I keep it, especially if its novel and relatively unknown.  So today we have a bit of the story of Tier Logic.  Tier Logic set out to make FPGA (Field Programmable Gate Arrays) better, and to make the transition (or choice) between them and ASICs (Application Specific Integrated Circuit) easier.

FPGA’s are great for smaller product runs, they are configurable, and relatively easy to reprogram, designs can easily be updated/tested with no additional cost.  FPGA’s however are large in terms of die area, power budgets, and cost per chip.  ASIC’s on the other hand, take longer to develop (re-spinning silicon every time an error is found) and have a much larger upfront cost, as well as an entirely different tool chain to design with. They are however smaller, use less power, and once the design is finalized, the per unit cost is very low.  This presents a dilemma in design, which should one choose for a project?  What if you didn’t have to choose? What if you could have the flexibility of an FPGA, and the benefits of an ASIC all at once?

It is exactly this that Tier Logic set out to do.  Tier Logic was founded by FPGA process-technology pioneer Raminda Madurawe (from Altera) in 2003 and was led by Doug Laird, a founder of Transmeta (famous for the Crusoe VLIW processors).  For 7 years they worked to design a solution, working in what is known as ‘stealth mode.’  Stealth mode is a way for companies to work quietly, with little to know PR, until they have a product ready to release.  Often the company exists but is completely unknown to outsiders.  This has some definite benefits, there is no constant barrage of having to answer/report to the media and others, and their is less risk of someone seeing what you are doing and trying to beat you to market to it.  Seven years, however, is a very long time to be in stealth mode, and the reason for this is Tier Logic not only was inventing a new style of FPGA/ASIC, they had to develop a new silicon process to make it work.

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March 31st, 2019 ~ by admin

CPU of the Day: CS603RMP-200 PowerPC 603r Goes Golden

Chip Supply Inc. CS603RMP-200 – 2005 Production Miltemp PowerPC 603r

The original PowerPC 603 was released way back in 1994, made on a 0.5u process and running at 75MHz.  A year later, the greatly improved PowerPC 603e was released, made on the same process, but supporting speeds of up to 200MHz.  It doubled the L1 caches to 16K each (for Instruction and Data) and introduced some Power Down modes useful for mobile and other low power applications.  A die shrink to 0.5u allowed speeds of up to 300MHz.

The 603e was available in both BGA  and cerquad packages, which worked for most applications.  But what if you wanted something a bit different?  What if your application needed something a bit more robust.  This is where packaging and die specialist companies come into play.  Motorola/IBM had no desire to make short runs of oddball packages and/or dies screened for higher end use.  Other companies however, did…

Motorola MPC603ERX100LN – 2000 vintage PowerPC 603e

Chip Supply Inc. was founded back in 1978 in Orlando, FL  just for this purpose.  Chip Supply provided die testing and packaging services for many different companies.  They also provided a service known as ‘die banking’ and just as the name implies, this involves collection and storing wafers and/or dies for future use.  This helped with end-of-life products especially.  As manufacturers slowed, changed, or stopped production of a device, dies for it could be made available through firms like Chip Supply.

In 1997 Chip Supply Inc. signed an agreement with Motorola giving them access to bare dies and known good dies for the PowerPC 603e, MPC106/7 PCI Bridge, and the MC68000 line.  This allowed Chip Supply to source dies from Motorola, screen them for higher spec (Military and Industrial temp typically).  Motorola had a similar agreement with Thomson-CSF (later this line was acquired by Atmel) who did the same thing, but also made radiation tested parts for space use (notably used on the original Iridium satellite constellation).

16×16 PGA in a 50mm package. Pins are 6mm long (twice as long as a Socket 7 Pentium)

The CS603RMP-200 is a 200MHz PowerPC 603r processor.  The 603r is nearly identical to the 603e, but allows for lower voltages (2.5V) and is made on a 0.29u process.  Chip Supply packaged this in a 16×16 CPGA package that is 50mmx50mm (nearly 2 inches square). It includes a large, gold plated heatspreader thats about the same size as a typical BGA PowerPC 603e.  These use original Motorola dies, upcreened to Military temperature (-55-125C) and tested to run at 200MHz.  The large heatspreader and ceramic package allow for better thermal management, and better mechanical support.  Thermal cycling and vibrations often result in BGA connection failures (a familiar problem on some game consoles in the early 2000’s), something a properly mounted PGA chip is much more tolerant of.

Chip Supply Inc. was acquired by Micross Components in 2010, a company that formed in 1998, and provided the same services with the addition of radiation testing. It appears that this was the end of the line for the entire PowerPC line by Chip Supply, though its likely that custom orders could be fulfilled for sometime after the acquisition.   Someday perhaps we’ll find out what applications the PGA PowerPC 603s were used in.

March 1st, 2019 ~ by admin

CPU of the Day: UTMC UT69R000: The RISC with a Trick

UTMC UT69R000-12WCC 12MHz 16-bit RISC -1992

We have previously covered several MIL-STD-1750A compatible processors as well as the history and design of them.  As a reminder the 1750A standard is an Instruction Set Architecture, specifying exactly what instructions the processor must support, and how it should process interrupts etc.  It is agnostic, meaning it doesn’t care. how that ISA is implemented, a designers can implement the design in CMOS, NMOS, Bipolar, or anything else needed to meet the physical needs, as long as it can process 1750A instructions.

Today we are going to look at the result of that by looking at a processor that ISN’T a 1750A design.  That processor is a 16-bit RISC processor originally made by UTMC (United Technologies Microelectronics Center).  UTMC was based in Colorado Springs, CO, and originally was formed to bring a semiconductor arm to United Technology, including their acquisition of Mostek, which later was sold to Thomson of France. After selling Mostek, UTMC focussed on the military/high reliability marked, making many ASICs and radhard parts including MIL-STD-1553 bus products and 1750A processors.  The UT69R000 was designed in the late 1980’s for use in military and space applications and is a fairly classic RISC design with 20 16-bit registers, a 32-bit Accumulator, a 64K data space and a 1M address space.  Internally it is built around a 32-bit ALU and can process instructions in 2 clock cycles, resulting in 8MIPS at 16MHz.  The 69R000 is built on a 1.5u twin-well CMOS process that is designed to be radiation hardened (this isn’t your normal PC processor afterall).  In 1998 UTMC sold its microelectronics division to Aeroflex, and today, it is part of the English company Cobham.

UTMC UT1750AR – 1990 RISC based 1750A Emulation

UTMC also made a 1750A processor, known as the UT1750AR, and if you might wonder why the ‘R’ is added at the end.  The ‘R’ denotes that this 1750A has a RISC mode available.  If the M1750 pin is tied high, the processor works as a 1750A processor, tied low, it runs in 16-bit RISC mode.  How is this possible? Because the UT1750AR is a UT69R000 processor internally.  Its the same die inside the package, and the pinout is almost the same (internally it may be but that’s hard to tell).  In order for the UT1750AR to work as a 1750A it needs an 8Kx16 external ROM.  This ROM (supplied by UTMC) includes translations from 1750A instructions to RISC macro-ops, not unlike how modern day processors handle x86.  The processor receives a 1750A instruction, passes it to the ROM for translation, and then processes the result in its native RISC instructions.   There is of course a performance penalty, processing code this way results in 1750A code execution rates of 0.8MIPS at 16MHz, a 90% performance hit over the native RISC.  For comparison sake, the Fairchild F9450 processor, also a 1750A compatible CPU, executes around 1.5MIPS at 20MHz (clock for clock, about 30% faster), and thats in a power hungry Bipolar process, so the RISC translation isn’t terrible for most uses.

NASA Aeronomy of Ice in the Mesosphere – Camera powered by RISC

By today’s standards, even of space based processors, the UT69R000 is a bit underpowered, but it still has found wide use in space applications.  Not as a main processor, but as a support processor, usually supporting equipment that needs to be always on, and always ready.  One of the more famous mission the UT69R000 served on was powering the twin uplink computers for the DAWN asteroid mission (which only this year ended).  It was also used on various instrumentation on the now retired Space Shuttles. The CPU also powered the camera system on the (also retired) Earth Observing-1 Satellite, taking stellar pictures of our planet for 16 years from 2000-2017.  Another user is the NASA AIM satellite that explores clouds at the edge of space, originally designed to last a couple years, its mission which started in 2007 is still going.  The

JAXA/ESA Hinode SOLAR-B Observatory

cameras providing the pretty pictures are powered by the UT69R000.  A JAXA/ESA mission known as SOLAR-B/Hinode is also still flying and running a Sun observing telescope powered by the little RISC processor.

There are many many more missions and uses of the UT69R000, finding them all is a bit tricky, as rarely does a processor like this get any of the press, its almost always the Command/Data Processor, these days things like the BAE RAD750, and LEON SPARC processors, but for many things in space, and on Earth, 16-bits its all the RISC you need.