Old mystery chip (AMI) - Page 1
Forum section: electronics / general

author: jannek
author_rank: Newbie
timestamp: December 23, 2018, 10:46:15 pm
content: Hello Fellows,Years back I bought a literal pile of old electronics from friend that needed to clean the place for repairing his cars.Old bakelite and maybe even few lathe turned wooden audio connectors iirc., glass tube fuses that start to fall into pieces etc.etc. and one mystery chip that looks cool.I think it's time to find out what the chip is. Someone recognized the logo as old American Microsystems logo. Not sure if they were just a fab for chips or did they have their own designs but they were involved in microprocessors and calculator chips back in the 70s. Even in the very first microprocessor chipset MP944 (F-14 CADC) but by the looks of it this chip is quite certainly newer if compared to grude looks of MP944 chipset but before era or plastic packages in early-mid 70'sSo I don't think the what would be timecode is actual timecode.Anyone have any idea what this chip is? Photos attacted. Price was 300 finnish marks. Chip has been used but not sure if before or after buying it.It's all I know.Also, MP944 was a beast for it's timeCheck link to get impressed.http://firstmicroprocessor.com/

author: jannek
author_rank: Newbie
timestamp: December 02, 2019, 01:43:50 am
content: Bump?

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 06, 2019, 02:19:39 pm
content: I do not recall AMI using that logo. That does not mean that it cannot be AMI. I interpret the bottom number as a date code-- Week 21 of 1968. The oldest catalog I have for AMI is 1976. It is no help. AMI made their own products and they did custom product designs as well.

author: Stray Electron
author_rank: Super Contributor
timestamp: December 06, 2019, 04:00:56 pm
content: I have a bunch of old AMI ICs but I don't recall that style logo either. The gray traces indicate that that's a very early production IC but the label says that it was made in Korea!I don't recall ever seeing AMI ICs that were made in Korea. I wonder if this is from a different AMI and this AMI was based in Korea? I have some old IC Master catalogs, if I have time, I'll look through them later and see what I can find out.I don't think that AMI (US) was around in 1968 and I don't think anyone was making Large Scale Integrated ICs that early. I think Intel started making LSI ICs in about 1973 and they were probably the first, or one of the first, to make them.PS I think the 7420 number is probably the date code. That would be about right for that style IC (white ceramic body, gold lid and pins and gray traces from the pins to the die body and with the locator holes in the IC.) Look around the edge of the lid and see if it looks like it was soldered on.

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 06, 2019, 05:46:45 pm
content: Quote from: Stray Electron on December 06, 2019, 04:00:56 pmMe either. It was a US fab.QuoteWikichip says they were founded in 1966. I have their book, "MOS Integrated Circuits" copyright 1972. They would have to have been working on it several years.QuoteCould be. Typically back then, the date code did not get top billing.I don't think this package style would be unusual for the late 60's, but I don't have any data to support that feeling.

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 06, 2019, 06:02:23 pm
content: If you have a microscope, pop the lid and see what it looks like. A memory (RAM, ROM, etc) will be obvious. Also, it may have additional markings that would be helpful.

author: Stray Electron
author_rank: Super Contributor
timestamp: December 06, 2019, 06:31:34 pm
content: I pulled out my 1983 copy of IC Master and I can't find anything like that. There are no 7420 numbers with that format and no 2168 numbers with that format from any company and there is no record of AMI (US) producing any standard part containing either of those numbers. The only logo that the ICM shows for AMI is the box with the arrow inside that is pointing to the top RH corner.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 06, 2019, 07:23:41 pm
content: It could be some kind of custom hybrid.

author: Stray Electron
author_rank: Super Contributor
timestamp: December 06, 2019, 08:06:43 pm
content: OK I finally found my 1980 edition of the IC Master. I can't find any of those numbers but the manufacturer's section shows that logo and says that it is "Discontinued" and that the current logo is the arrow in the box.The numbers on the OP's part don't match the PN description shown in this book. The part number should start with a "S" for a standard package and have letters at the end of the PN that specify the version number and then a dash "-" and another letter that specifies the package material and the number of pins. Note that the chart in this book does not list a 40 pin ceramic package.

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 06, 2019, 08:30:26 pm
content: Quote from: Stray Electron on December 06, 2019, 08:06:43 pmNice work Stray! Did it give a name?

author: Stray Electron
author_rank: Super Contributor
timestamp: December 06, 2019, 08:47:46 pm
content: "Did it give a name?"No, nothing that even looked remotely like this IC part number. This was just a short section that showed the company logos and how their part numbers were supposed to be broken down. Or did you mean the name of the company? If so, then yes, AMI was American Microsystems, Inc. They were later renamed to AMI Semiconductor (AMIS). FWIW the net shows that they were founded in 1966.In fact there only one part containing "7420" in this edition. By 1893 there were about 9 or 10 companies that made a part that contained "7420" as part of their part number.The OP's part appears to have been made well before 1980.

author: SpecialK
author_rank: Regular Contributor
timestamp: December 07, 2019, 04:35:22 pm
content: It seems that AMI did change their logo around 1975:https://www.ebay.com/itm/S1883-AMI-40-PIN-CERAMIC-WHITE-LEAD-TRACE-VINTAGE-1975-COLLECTIBLE-ORIG-CARRIER-/372151247045This website details that AMI did build a facility in Korea to build chips for the burgeoning calculator market:http://www.thechofamily.com/KMI-Product.htmlOf interest, is that they located to Korea to supply chips to Ricoh.This site has some information on AMI buying Unicom, a calculator distributor.https://www.oldcalculatormuseum.com/timeline.htmlI would say this chip looks consistent with several old calculators from the early seventies. Commodore, Ricoh, and Burroughs to name a few.

author: Wimberleytech
author_rank: Super Contributor
timestamp: December 07, 2019, 05:46:24 pm
content: Good sleuthing SpecialK !!

author: SpecialK
author_rank: Regular Contributor
timestamp: December 07, 2019, 07:29:25 pm
content: Quote from: Wimberleytech on December 07, 2019, 05:46:24 pmThanks. I've been lurking this site for quite some time. I wasn't planning on joining until I had something worthy to contribute. Today was the day I suppose.That chip seems to be a significant piece of history. Display case worthy I'd say. I'd try to reach out to someone from the Cho family website's contact page if I were jannek. Last updated about 2014 from what I can tell.

author: jannek
author_rank: Newbie
timestamp: December 11, 2019, 02:07:17 am
content: Thanks Guys!It's exciting to know this chip is indeed old and.. rare I think?I'll ask Mr. Cho more about this chip.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 11, 2019, 11:30:05 am
content: Quote from: jannek on December 23, 2018, 10:46:15 pmI am much more interested in the "hand turned wooden audio connectors"-----I've been "around since Adam", & I have never seen such things.They sound like an early version of "audiophoolery"!

author: SpecialK
author_rank: Regular Contributor
timestamp: December 12, 2019, 01:27:01 am
content: Quote from: vk6zgo on December 11, 2019, 11:30:05 amMust be this "finnish carpentry" I've been hearing about...