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:
- 19: National Semiconductor (NSC). See this TT mainboard, where on the right the DCU has both NSC logo and the "-19" marking. http://www.strotmann.de/~beetle/images/ ... 030226.JPG
- 20: Mystery supplier. Made the chipset for early STs: http://www.atari-wiki.com/images/1/18/S ... jokker.jpg. Note that this supplier also made the MMU in the 130XE: http://ataricomputers.altervista.org/13 ... _FRONT.jpg
- 28: SGS-Thomson (ST). See the Blitter in this MegaST: http://www.exxoshost.co.uk/atari/last/M ... egastb.jpg
- 31: International Microelectronic Products (IMP). See the chipset in this MegaST: http://www.exxoshost.co.uk/atari/last/M ... egastb.jpg
- 36: General Electric/RCA. See this Blitter: http://forum.atari-home.de/index.php?ac ... 3518;image
- 38: Ricoh. Confirmed by ijor's die shot and by this MMU, a clearly marked Ricoh RF5GH23: http://forum.atari-home.de/index.php?ac ... 3489;image
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.