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Archive for the 'Research' Category

June 10th, 2018 ~ by admin

The Collector’s Guide to Vintage Intel Microchips

The CPU Shack Museum is proud to announce the availability of The Collector’s guide to Vintage Intel Microchips, written by George Phillips Jr. This e-book (PDF) contains over 1300 pages, and 900 photographs of Intel Microchips from the 1960’s and 70’s along with their functions, package variations, rarity, and valuations.  Everything from the 3101 Static RAM to the i4004 4-bit processor. The author, George Phillips, has moved this book into public domain.  Originally published back in 2007 it is still a very useful resource.  Being 10 years old, some of the values are inaccurate and there has been a few more Intel chip types from the 1970’s found since then, as well as some different package/marking variations.  However the Guide is really an important resource for any collection that includes Intel IC’s from the 1970’s.

I have been collecting information for an update to it for some time, so if you have any Intel chips/variations not in this guide, feel free to let me know.

You can download The Collector’s Guide to Vintage Intel Microchips here (pdf 22.9MB)

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Products, Research

March 21st, 2018 ~ by admin

Intel’s Chipped Chips

Early Intel 8080A processor (no date code) chipped and used in a Uni kit

Typically when collecting something, be it coins, cars or CPU’s having the most pristine unblemished example is highly desirable.  However, sometimes, the best example is one that isn’t perfect, in coin collecting it may be a rare double struck coin, or some other flaw that actually makes the coin more valuable.

In the 1970’s Intel put together many development kits for it’s processors.  These were to help engineers, companies, and even students learn how to use Intel’s products. Intel made several kits specifically for University use, including one based around the MCS-80 processor and another around the MCS-48 microcomputer.  The 8080 University kit came with an 8080 processor, and a variety of support chips, including RAM, EPROMs (usually 1702s), clock drivers, bus drivers etc.  They were often a mix of packages, including plastic, and ceramic, with many chips being marked ‘CS‘ which is Intel’s designation for a Customer Sample.

Military MC8080A CS from a Uni kit. Multiple chipped corners. Such damage often was a result of improper packing in an IC shipping tube.

The price of the kits was kept low, the purpose was to get people use to using Intel products, not to make money.  Due to this, Intel tried to build the kits in the most efficient way possible.  Almost every 8080 University kit included a working, but cosmetically damaged C8080A processor.  These were typically the white/gold ceramic variety with a chipped corner.   It was very common to see a MC8080A or MC8080A/B military spec processor in a University kit, the processor would function fine, but had  some damage, enough that it could not be sold as a mil-spec processor (which has requirements for screening out such damage). The damaged chip would simply be tested, stamped ‘CS‘ and stuck in a kit, ths saving Intel money and keeping a working processor from being wasted.   The same thing happened with the MCS-48 University kits, these included chips such as the D8035 or C8748 MCU, and again, often shipped with damaged chips.

It turns out that the most correct, authentic chip, in a University Kit, was the cosmetically challenged, and in a way, this makes them more uncommon and more interesting.  Its due to their damage that they were selected for the special use in a University kit.  The irony is that many times it was the highest end military screened chips, that ended up getting used in one of the lowest end products.

July 3rd, 2016 ~ by admin

Juno Joins Jupiter: And Brings Some Computers For The Trip

Juno - RAD750 Powered Mission to Jupiter

Juno – RAD750 Powered Mission to Jupiter

NASA’s Juno mission to Jupiter arrives in just about a day, after a 5 year journey that began in August of 2011 aboard an Atlas V rocket.  The Juno mission is primarily concerned with studying the magnetic fields, particles, and structure of Jupiter.  Finding out how Jupiter works, and what its core is made of are some of Juno’s goals.  None of the experiments need a camera, but NASA decided, in the interest of public outreach and education, that if you are going to spend $1 billion to send a probe to Jupiter, it probably should have a camera.  Energetic particle detectors, Magnetometers, and Auroral Mappers are great for science, but what the public is inspired by is pretty pictures of wild and distant worlds.

Juno is powered by a now familiar computer, the BAE RAD750 PowerPC radiation hardened computer.  It operates at up to 200MHz (about the processing power of a mid 1990’s Apple Computer) and includes 256MB of Flash memory and 128MB of DRAM.  It (and the other electronics) are encased in a 1cm thick titanium radiation vault.  Flying in a polar orbit around Jupiter, Juno will experience intense radiation and magnetic fields.  The probe is expected to encounter radiation levels in the order of 10Mrads+.  The vault limits this to 25krads, within what the electronics can handle.  It should be noted that a dose of 10krads is fatal in most cases.  This intense of radiation will degrade the prober, even with shielding, resulting in a mission life of only 37 orbits (a little over a year) before the probe will be gracefully crashed into Jupiter.

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March 13th, 2016 ~ by admin

Part 3: Vintage IC Collecting – The How.

In Part 1 of our three part series on IC collecting we discussed why to collect vintage computer chips. For Part 2 we covered what to collect, how to set and keep a focus in your collection. For the final Part we’ll cover some of the ways of how to find and collect the IC’s you want.

Part 1: Why Collect Vintage Chips?
Part 2: What Vintage Chips should I Collect?
Part 3: How do I collect Vintage IC’s?

There are two main parts of the How of IC collecting. Where to I get my chips? and Where do I put them?  For most collectors cost is a concern, for the right money you can have most any chip, but since i have yet to find the dollar/Euro/yen tree cost is a factor in acquiring chips.  One of the greatest sources of chips is eBay.  Several categories in particular are a good source of chips, IC?Processors in the Business/Industrial category, the CPU/Processors and Vintage categories in Computing, and Scrap/Recovered Gold.  Of these Scrap Gold can yield some of the most interesting chips.  Scrap sellers in general though have no idea about what they are selling (as far as collectibility) but most are happy to work with you.  If you win a lot with a nice chip in it, send the seller a note to pack the chips well, and in most cases they will.  They are sold as scrap though so keep that in mind if they don’t come in perfect shape. This can be a good chance to learn the art of pin straightening.

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March 1st, 2016 ~ by admin

Part 2: Vintage IC Collecting – The What.

Where do I start? Where do I end? Focus!

Where do I start? Where do I end? Focus!

In Part 1 of our three part series on IC collecting we discussed why to collect vintage computer chips.  For Part 2 we’ll cover what to collect. which is the most important part of collecting (not just IC’s but anything).

Part 1: Why Collect Vintage Chips?
Part 2: What Vintage Chips should I Collect?
Part 3: How do I collect Vintage IC’s?

There are millions of different IC’s made since the dawn of the IC in the 1950’s, obviously it would not be prudent to try to attempt to collect all of them, so one needs to set a focus for their collection.  The earlier this is done, the easier collecting will be, and the less chance of going insane, broke, or both.  The CPU Shack, as the name implies, began collecting just CPU’s, the brains of computers.  Through the years (and due to things being donated to the museum) this has expanded to microcontrollers, SoCs. UV-EPROMs. GPU’s, and even the occasional DSP.  It’s a broader slice of IC’s then most would want to attemp, at least when starting.  So let’s figure out ways to gain a focus in collecting.

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February 18th, 2016 ~ by admin

Part 1: Vintage IC Collecting – The Why.

First Start of IC Collecting

First Start of IC Collecting

This will be the beginning of a three part series on Vintage IC Collecting, as I get asked a lot, ‘why do you collect computer stuff?’ and How do you do it? Where do you find chips etc.

Part 1: Why Collect Vintage Chips?
Part 2: What Vintage Chips should I Collect?
Part 3: How do I collect Vintage IC’s?

These really are the fundamentals to collecting/curating anything, and are important if you wish to have any structure to your hobby of collecting.  Collecting itself seems to be built into human nature, and psychologists and evolutionary scientists have many theories as to why.. Freud, who else, claimed that people collect things due to ‘unresolved toilet training issues.’ Others see collecting as a evolutionary strength, that allowed for a better chance of survival, those that collected scarce resources, had a better chance of living to procreate.

Myself, I started collecting coins when I was young, among other things.  While scrapping out computers in High School I figured the processors should be saved, as the ‘brains’ of the computer, and thus my hobby, and the museum, began.

The Collection Progresses

The Collection Progresses

There really has become two main reasons for continuing to do so.  First, I see a need to preserve some small portion of the technology that has driven us to where we are today, and where we are going.  Second, its genuinely fun, the hunt for new chips, the research into finding where they were used, and why they were made and the camaraderie with fellow collectors.

This leads us to the Why, specifically for collecting Vintage IC’s.  Many assume that those who collect computer chips will be ‘a bunch of nerds’ and while some certainly are, there is a great variety.  Like other collecting areas, there are those who collect for economic reasons, they see a good deal, buy it, with the intent of reselling it for profit at some later date, and there is certainly nothing wrong with this.  Others have some historical connection with the chips they collect.  They may be retired Electrical/Computer Engineers, programmers and the like, that see collecting as a way to preserve some of what they did.

It gets big quickly without proper focus

It gets big quickly without proper focus

For some collecting computer chips is a matter of convenience, they have ready access to them (recycling, etc) and are drawn to the fact, that like coins, IC’s have an extrinsic value in their rarity, obscurity, or provenance, but also some intrinsic value in the precious metals they contain.  Computers chips also have the benefit that their entire history is contained in a period of time that numbers in the decades, 50 years, shorter than an average human lifetime, contains the current sum of IC history.  This can be seen to make the hobby more ‘manageable’ though we will see if Part 2, that this may not be the case.

For some, computers chips are shiny, pretty, and look ‘cool’ and thats all thats needed, they collect not for any historical, or technological reason, but for the fact that they like neat looking ‘stuff’.  Some collect very large/gold chips only for this reason, or wafers, because they are drawn first, to their beauty.
On the extreme of this is those, as a fellow collector in Romania once told me:

“Basically when I saw in the same place 3 different objects of the same type, my first thought is ” I should start a new collection”

And sometimes, that’s all it takes to get started.  Next week we will explore the What of collecting, how to determine what specific type of IC’s you want to collect, and figuring that out early is so important.

February 8th, 2016 ~ by admin

Reverse Engineering the ARM1 Processor

VLSI VL2333-QC ARM ACORN - ARM2 (Adds MULT instruction in hardware) 1987

VLSI VL2333-QC ARM ACORN – ARM2 (Adds MULT instruction in hardware) 1987

Ken Shirriff has an interesting article on reverse engineering the original ARM1 processor (as designed by ARM, and implemented by VLSI).  He goes right to the silicon to form a transistor level model/emulator of the chip.  Back in 1986 when the ARM was designed and released, it wasn’t very well known, being used in very few devices.  This continued for over a decade surprisingly. being used in niche markets (the Apple Newton, the DEC StrongARM on RAID cards, etc).  It wasn’t until the 2000’s that this processor startup from England became the powerhouse it is today.  Two major developments drove this, mobile, and multimedia.  The ARM architecture was powerful, small, and easy on the power budget, this obviously was a benefit for mobile, but also proved very useful in dealing with multimedia processing, such as controllers on DVD players, digital picture frames, MP3 players and the like.  Today, hundreds of companies license and use the architecture and it is found in devices now numbering in the billions.


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October 15th, 2014 ~ by admin

Has the FDIV bug met its match? Enter the Intel FSIN bug

Intel A80501-60 SX753 - Early 1993 containing the FDIV bug

Intel A80501-60 SX753 – Early 1993 containing the FDIV bug

In 1994 Intel had a bit of an issue.  The newly released Pentium processor, replacement for the now 5 year old i486 had a bit of a problem, it couldn’t properly compute floating point division in some cases.  The FDIV instructions on the Pentium used a lookup table (Programmable Logic Array) to speed calculation.  This PLA had 1066 entries, which were mostly correct except 5 out of the 1066 did not get written to the PLA due to a programming error, so any calculation that hit one of those 5 cells, would result in an erroneous result.  A fairly significant error but not at all uncommon, bugs in processors are fairly common.  They are found, documented as errata, and if serious enough, and practical, fixed in the next silicon revision.

What made the FDIV infamous was, in the terms of the 21st century, it went viral.  The media, who really had little understanding of such things, caught wind and reported it as if it was the end of computing.  Intel was forced to enact a lifetime replacement program for effected chips.  Now the FDIV bug is the stuff of computer history, a lesson in bad PR more then bad silicon.

Current Intel processors also suffer from bad math, though in this case its the FSIN (and FCOS) instructions.  these instructions calculate the sine of float point numbers.  The big problem here is Intel’s documentation says the instruction is nearly perfect over a VERY wide range of inputs.  It turns out, according to extensive research by Bruce Dawson, of Google, to be very inaccurate, and not just for a limited set of inputs.

Interestingly the root of the cause is another look-up table, in this case the hard coded value of pi, which Intel, for whatever reason, limited to just 66-bits. a value much too inaccurate for an 80-bit FPU.

October 11th, 2014 ~ by admin

Why the Zilog Z-80’s data pins are scrambled

Zilog Z80A CPU -1978

Zilog Z80A CPU -1978

Ken Shirriff has an excellent write up about the Zilog Z80 and why its pin-out, specifically the Data lines, is a bit convoluted.  Rather then being in order (such as D0-D7) the original Z80 is D4,D3.D5,D6,D2,D7,D0,D.  Its functional but its not pretty and can lead to some interesting PCB layout issues.  Ken uses data/imaging from the Visual6502 project to look at the on die reasons for this.  Essentially it came down to saving die space. there literally was not enough room to route the data connections within the confines of the die size.  Keeping the die size small allowed Zilog, and its many second sources), to keep prices down.  In the early days Zilog contracted Mostek to make much of their processors, so die size and the associated cost were a big issue.

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November 1st, 2013 ~ by admin

nCube and the Rise of the HyperCubes

nCube/2 Processor - 20MHz The logo is a tesseract - 4-way Hypercube

nCube/2 Processor – 20MHz
The logo is a Tesseract – a 4-way Hypercube

In 1983 Stephen Colley, Dave Jurasek, John Palmer and 3 others from Intel’s Systems Group left Intel, frustrated by Intel’s seeming reluctance to enter the then emerging parallel computing market.  They founded a company in Beaverton, Oregon known as nCube with the goal of producing MIMD (Multiple Instruction Multiple Data) parallel computers.  In 1985 they released their first computer, known as the nCube/10.  The nCube/10 was built using a custom 32-bit CMOS processor containing 160,000 transistors and running initially at 8MHz (later increased to 10).  IEEE754 64-bit floating point support  (including hardware sqrt) was included on chip.  Each processor was on a module with its own 128KB of ECC DRAM memory (implemented as 6 64k x 4 bit DRAMs.)  A full system, with 1024 processor nodes, had 128MB of usable memory (160MB of  DRAM counting those used for ECC).  From the outset the nCube systems were designed for reliability, with MTBFs of full systems running in the 6 month range, extremely good at the time.

The nCube/10 system was organized in a Hypercube geometry, with the 10 signifying its ability to scale to a 10-way Hypercube, also known as a dekeract.  This architecture allows for any processor to be a maximum of 10-hops from any other processor.  The benefits are greatly reduced latency in cross processor communication.  The downside is that expansion is restricted to powers of 2 (64, 128, 256, 512 etc) making upgrade costs a bit expensive as the size scaled up.  Each processor contained 22 DMA channels, with a pair being reserved for I/O to the host processor and the remaining 20 (10 in + 10 out) used for interprocessor communication.  This focus on a general purpose CPU with built in networking support is very similar to the Inmos Transputer, which at the time, was making similar inroads in the European market.  System management was run by similar nCube processors on Graphics, Disk, and I/O cards.  Programming was via Fortran 77 and later C/C++. At the time it was one of the fastest computers on the planet, even challenging the almighty Cray.  And it was about to get faster.

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