Archive for October, 2017

October 22nd, 2017 ~ by admin

The CPU Shack Gets a Scope

Microscope – Packed with a free roll of tape

For quite some time I have wanted a microscope for the Museum.  It would be very useful for inspecting unknown wafers and dies, as well as learning a lot more about EPROM dies.  So often one die is used for many devices, often of different sizes or even manufacturers.  Recently the Museum also received a whole bunch of MIPS prototypes, mostly all unmarked, and all with open die covers.  The only way to positively identify them, and find all the die art that the MIPS designers added, is with a scope.

Make that 2 rolls of tape

A good deal on an Accu-Ray 3035 inverted metallurgical scope showed up on eBay.  These sell new for over $2000 so at under $400 it was a good deal.  Its cost was covered by donations by many other collectors around the world, who are most likely hoping it results in more interesting article and

pretty pictures.  Metallurgical scopes are a bit different from your typical microscope.  The ‘normal’ scope is a transmitted light device, shining light THROUGH the sample into the objective.  Clearly this doesn’t work for opaque and solid items, such as wafers.  These need to use reflected light, which is a bit harder to work with.  Light is shown on the sample and reflected back into the objective.  The Accu-Ray came with 10x, 25x 40x and 60x objectives, though for wafer work 25x really is about the limit of what is needed (and it gets harder to light samples at the higher magnifica

Accu-Ray 3035 Inverted Microscope

tions).  The standard eyepieces are 10x so this results in 100x-250x magnification.  I have ordered a 4x objective and a 20x as well, which should give a good range.  The higher power

objectives have a smaller working distance, meaning they have to be much closer to the wafer/die, that can be tricky when the die is mounted in a package, or several millimeters under a window on an EPROM.

The physics of a microscope are a well understood science, getting light through the scope, to the wafer, and to the eyepiece in a way you can see anything turns out to be more of an art.  Dealing with a mirror like silicon surface, glare becomes a huge problem, so that is what I am

Quick shot through the eyepiece of a MIP R10000

learning about now, how to light the wafers.  The included halogen light is very nice and very bright but with wafers results in massive glare that makes seeing the wafer near impossible.  Using and LED flashlight (it bolts right up to the scope, surprisingly) results in much more even lighting, albeit less of it.  I have ordered a diffuser which should help even out the light from the halogen, hopefully that helps.

As soon as I get a good reliable set up you can look forward to some interesting pictures and hopefully some interesting new information.

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Museum News

October 14th, 2017 ~ by admin

VLSI: What is this THING?

VLSI VY12338 THING UA-JET238-01 – Made in 1997

VLSI was started back in 1979 by several former Fairchild employees, 2 of which had previously founded Synertek, a connection that becomes important later on.  VLSI is best known for being a contract deign/fab services company.  They excelled at custom, and semi-custom designs for a wide range of customers, as well as acting as a foundry for customers own designs.  They became best known for their part in the development and success of the ARM processor back in the late 1980’s with ACORN.  They manufactured, as well as marketed and sold, several versions of the ARM processor, one of the few processors they actually sold themselves.  They also made a 6502 used by Apple and 65C816 (CMOS 16-bit 6502).  The 6502 was also a processor that Synertek had made back before Dan Floyd, and Gunnar Wetlesen left Synertek to start VLSI.

VLSI went on to fab processors for some of the biggest companies of the 1980’s.  The made the processor for several Honeywell BULL mainframes, built the processor for the HP A990 computer, and made dozens of chips for SGI and WANG.  VLSI also enjoyed wide success in the early 1990’s making chipsets for 486 processors, before Intel began to offer chipsets on their own in the Pentium era.

Unfortunately like LSI, most of VLSI’s designs are relatively unknown to all but them and their customer.  Marking on the chips rarely provide information on who it was made for, and even less on what exactly it does.  The above chip, marked “VY12338 THING UA-JET238-01” seems to be names as an answer to the question “What do we call this thing?”  Certainly seems to be a bit of humor on the part of some engineer.

VLSI was bought by Philips (now NXP) in 1999 so the THING may forever remain an unknown thing.

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Just For Fun