List of Atari ASIC suppliers

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czietz
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List of Atari ASIC suppliers

Postby czietz » Sat Apr 29, 2017 8:14 am

Hello,

I've come to the conclusion that the supplier of an Atari ASIC can often be determined by a two digit code on the package. Sometimes (often in older ICs) this code is directly appended to the Atari part number Cxxxxx, sometimes (often in newer ICs) it is printed separately. After reviewing many photos on the Internet and also my own collection of ASICs, I got the following table. I'll also add a link to a sample for each entry:


Can anyone shed light on the mystery supplier -20 or contribute additional entries?


Note that with the Blitter there are some oddities: Blitters made by NSC neither had an Atari part number nor the "-19" marking, see for example http://www.exxoshost.co.uk/atari/last/MEGAST/mega5.jpg. Also there were Blitters made by Innovative Silicon Technology (IST), like this one https://upload.wikimedia.org/wikipedia/ ... litter.jpg, without a two digit code. IST was a subsidiary of SGS.

czietz
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Re: List of Atari ASIC suppliers

Postby czietz » Sun Apr 30, 2017 9:49 am

czietz wrote:Can anyone shed light on the mystery supplier -20 or contribute additional entries?


Also, if you happen to have a (most likely very early) 520ST with -20 chips (be it MMU, GLUE, DMA or Shifter), you can help me by looking if there are any markings on the bottom side of those ICs that might help identifying the supplier.

czietz
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Re: List of Atari ASIC suppliers

Postby czietz » Sun May 07, 2017 7:54 pm

After a lot of research, I have not proof but very concrete indications that the -20 supplier was Universal Semiconductor from San Jose, CA. Recall that these chips are labeled 3G-2120-BC, 3H-2119-CC, 3H-2123-AA and 3H-2130-?? (big gate count, GLUE, MMU, Shifter and DMA, PLCC or large DIP package) in the 520ST [1] and 3J-2100, 3J-2139 (presumably small gate count, MMU, EMMU, small DIP package) in the 130XE. [2]

In the early 1980s Universal Semiconductor offered the ISO-3 CMOS gate array series [3], 3J being the smallest ones (available in small DIP), 3G and 3H being bigger ones (available in bigger packages, such as PLCC or DIP40). On its own, this could very well be a coincidence. But there is proof [4] that Universal Semiconductor manufactured a gate array designated 3H-2185-AA for another customer -- Tektronix.

Now, without getting a -20 chip into my hands I cannot be sure -- and even then, there may be no hidden marks -- but imho this information strongly indicates that Universal Semiconductor is the mystery -20 supplier that I was looking for.

[1] http://www.atari-wiki.com/images/1/18/S ... jokker.jpg
[2] http://ataricomputers.altervista.org/13 ... _FRONT.jpg
[3] http://datasheet.datasheetarchive.com/o ... 150642.pdf
[4] http://www.armyproperty.com/product/0AEB1/3H-2185-AA/

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Re: List of Atari ASIC suppliers

Postby ijor » Mon May 08, 2017 12:35 pm

Great research work Christian! Probably your theory is correct. Thanks.

czietz
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Re: List of Atari ASIC suppliers

Postby czietz » Sat Jul 22, 2017 10:30 am

Even though I still haven't found a company to decapsulate my -20 ASIC sample, I have uncovered more information that in my opinion proves that the "mystery" -20 supplier was indeed Universal Semiconductor. The -20 manufacturer also was one of several suppliers of TIA ASICs for the VCS/2600. You can find a logo on some ICs [1]. This puzzled me, since Universal Semiconductor's more current logo [2] is completely different. But thanks to the Internet Archive, I uncovered an IC catalog from 1983 [3] that shows exactly the logo from [1] for Universal Semiconductor.

Combine this with the part numbering that I described in my previous post and I think we can now safely assume that -20 ASICs came from Universal Semiconductor.

[1] http://www.ataricompendium.com/faq/vcs_ ... 26-641.png
[2] http://photos.wikimapia.org/p/00/02/04/80/89_big.jpg
[3] https://archive.org/stream/bitsavers_ic ... 5/mode/2up


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