Identifying old ICs - Page 1
Forum section: electronics / general

author: kazzie
author_rank: Newbie
timestamp: July 25, 2018, 03:58:26 pm
content: Hello,I have two old ICs that I grabbed some months ago before they were thrown into a bin. They caught my eye as they're gold and white ceramic. I've attached a photo, but here's a textual description too:The first is a 14-pin DIP chip, with a fully-gold upper and lower portion sandwiching white ceramic in the middle, with gold pins. The top is labelled "PLESSEY / MP131B / 51974", there is no marking on the bottom.The second is a 24-pin DIP made of white ceramic, with a gold plate over the die area. There are two holes through the white ceramic, and a gold trace runs from the plate to the notch. The pins are again gold. The plate is labelled "GIM-0 / 16-M / D0876", the bottom of the chip is plain white ceramic.The manufacturer for the first is quite obvious; as for the second my best guess is General Instrument's Microelectronics division. The labels look like they include date codes from the 1970s. I've searched numerous online datasheet websites using variations of the label texts, and also looked through several old component books from the 1970s on archive.org, but to absolutely no avail. I can't find any evidence that Plessey had a line of ICs that were named MPxxx, and the other part's label is less that helpful. "16-M" made me think of ROM or RAM, which would fit with the 24-pin DIP shape, but that would bewaytoo large for 1976: 1977 saw the commercial release of 16Kilobit EPROMs.I don't know if these are functioning or not, I haven't applied any voltages to them as I don't know their pinouts, and want to avoid frying a potentially working chip by shoving the wrong polarity down its throat.I realise the odds of somebody recognising either of these on sight are very long, but I'd also be receptive to any suggestions on what further investigation I could do to try and work out what they are.Thanks.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 25, 2018, 04:24:44 pm
content: Hermetic ceramic packages with gold plated terminals? If you ask me, those are Aerospace or MIL-spec ICs. Probably full custom.If you cannot find what they are or how they work, set them in a nice frame and hang them as souvenirs in your office.These are prime examples of a bygone era where certain markets would pay stratospheric amounts of money for premium components. The cream of the crop of semiconductor manufacturing in that era.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: July 25, 2018, 04:51:52 pm
content: That big one is doubly unique: dog-leg pins and a slot in the ceramic package.

author: amyk
author_rank: Super Contributor
timestamp: July 26, 2018, 12:47:11 am
content: Fromhttps://www.americanradiohistory.com/Archive-Wireless-World/70s/Wireless-World-1970-01.pdfpage 93, we find this clue as to what the MP131B is. If anyone has a Plessey databook from the early 70s, that might be where to pursue this further.(There is one well-known datasheet site which claims it is a binary up/down counter, which it most certainly is not.)There are some "IC master" books on archive.org that you might be able to find more information about them in.

author: kazzie
author_rank: Newbie
timestamp: July 26, 2018, 12:04:28 pm
content: That's a great lead on the MP131B/ML150, amyk, thanks. I've found a mention of the planned introduction of the ML150 series in 1969here.TheIET Archivesin London have some papers relating to Plessey, and their catalogue mentions some datasheets for the ML151 and ML153, though nothing from the MP130 series. I wonder what 'MOSAIC' stood for (other than the obvious Metal Oxide Semiconductor)? I suppose that's another thing to add to my (already long) list of things to research when I next visit London.Thanks also for the suggestion of IC Master books. I hadn't come across these, and have had a browse through the oldest on Archive.org (1977). Sadly there's no sign of any Plessey ML15* or LP13* chips in the part number index, and the section on analogue switches (with or without drivers) lists nothing by Plessey. They may have pulled out of that sector of the market by 1977.With regard to Schmitt Trigger's observations, it's quite possible that these were custom or prototype ICs, as they came from an old university storeroom.They will end up getting displayed somewhere, but it'd be nice to know what they are, too.As for the large chip, can anyone tell me if the "GIM" designation is known to have been used by General Instrument, or suggest an alternative manufacturer?The two holes in the ceramic are a new concept to me. (As well as the slot,there's a circular hole beyond the die that doesn't show very well at the angle I photographed it. Why would such holes be there in the first place: something to do with physical manipulation of the chip during manufacture?Thanks again for your insight.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 26, 2018, 01:32:56 pm
content: I actually worked for General Instrument in the 1980s, although not for their microelectronics division.But we did use a lot of the micro division's ICs in our products. I also remember that GI had what was called a "Federal" division which did a lot of confidential military work.As far as I can remember General Instrument was always abbreviated "GI". They changed logos many times, I still have a softball cap with the round green "meatball" GI logo on it.

author: johnkenyon
author_rank: Regular Contributor
timestamp: July 27, 2018, 11:47:12 am
content: MOSAIC = "Metal Oxide Semiconductor Advanced Integrated Circuit, Plessey Trademark applied for"Found this athttps://books.google.co.uk/books?id=RcUgBQAAQBAJ&lpg=PA1533&ots=HUmVZLsZyO&dq=plessey%20MOSAIC&pg=PA1531#v=onepage&q=plessey%20MOSAIC&f=falsePage 1531 of "Anglo–American Microelectronics Data 1968–69"

author: amyk
author_rank: Super Contributor
timestamp: July 28, 2018, 12:50:06 am
content: Quote from: johnkenyon on July 27, 2018, 11:47:12 amThanks for reminding me I have the eBook of that, and indeed it contains ML153 and ML154 "advance data". I've extracted and attached the relevant pages. Unfortunately the book predates the MP13x, but that gives a further hint about where to find more information --- IC metacatalogs from ~1970 to '75 might have it.This is the most relevant:Plessey Integrated Circuit Databook 1974--- unfortunately I can't find a scan, butsomeone is selling a hardcopy(if anyone buys it, please scan and upload to archive.org....) There's also a 1973 edition floating out there.

author: Astrodev
author_rank: Regular Contributor
timestamp: July 31, 2018, 04:10:02 pm
content: I have got copies of some of the Plessey Databooks but can't find the box they are in at the moment, if I find the data I will scan it in for future reference.I also have a load of boxes of bits that came from Plessey's R&D at Cheney Manor which includes quite a few prototype hybrids that were constructed on thin glass plates which were then connected up and mounted in rectangular copper can enclosures which could then either be evacuated of filled with a gas mix, there were also some IC's in various states of build, an example of 2 is in the photo.One day I must go through and sort them out as I just got all this for a Keithley System 2 rack and at the time I considered the rest as junk but never got round to sorting it out and I suppose it is history.

author: Astrodev
author_rank: Regular Contributor
timestamp: July 31, 2018, 04:30:12 pm
content: Since I was doing some pictures I thought I would share this little montage.

author: schmitt trigger
author_rank: Super Contributor
timestamp: July 31, 2018, 05:28:46 pm
content: You DO HAVE some piece of computing history on that display!

author: Astrodev
author_rank: Regular Contributor
timestamp: July 31, 2018, 05:52:42 pm
content: Yes its a modulo 4 processor set 4, 8, 12 and 16bit

author: glarsson
author_rank: Frequent Contributor
timestamp: July 31, 2018, 06:24:05 pm
content: Quote from: Astrodev on July 31, 2018, 05:52:42 pm4040 is 4 bits.8080 and 1802 are 8 bits.8086 is 16 bits.12 bits?

author: Astrodev
author_rank: Regular Contributor
timestamp: July 31, 2018, 06:47:30 pm
content: Your right, for some reason I had it in mind that the CDP1802 was 12bit, that spoils the sequence.

author: james_s
author_rank: Super Contributor
timestamp: July 31, 2018, 06:53:54 pm
content: Was there ever a 12 bit processor? That would be news to me, I suppose some of the earlier pre-microprocessor architectures had unusual bit widths.

author: Astrodev
author_rank: Regular Contributor
timestamp: July 31, 2018, 06:56:52 pm
content: There were several one being the Intersil 6100

author: amyk
author_rank: Super Contributor
timestamp: August 01, 2018, 12:40:24 am
content: PDP-8 is one that comes to mind.

author: ebastler
author_rank: Super Contributor
timestamp: August 01, 2018, 09:18:11 am
content: Wikipedia knows of a few more:https://en.wikipedia.org/wiki/12-bitMost of them are rather obscure. The PDP-8 (and its LSI version, the Intersil/Harris 6100) is certainly the best-known architecture, probably followed -- at a fair distance -- by the LINC:https://en.wikipedia.org/wiki/LINC

author: james_s
author_rank: Super Contributor
timestamp: August 01, 2018, 03:58:46 pm
content: I knew at least one of the PDP systems used an odd bit width but I couldn't remember which one. Isn't the PDP-8 built around discrete logic though rather than a microprocessor?

author: glarsson
author_rank: Frequent Contributor
timestamp: August 01, 2018, 05:09:15 pm
content: Quote from: james_s on August 01, 2018, 03:58:46 pmThe PDP-8 was released in 1965. What microprocessor would that be?Discrete transistors and diodes (DTL logic) on pcb modules was used on the first models.

author: ebastler
author_rank: Super Contributor
timestamp: August 01, 2018, 08:06:20 pm
content: Quote from: james_s on August 01, 2018, 03:58:46 pmYep, the original PDP-8 was built from discrete transistors. Later versions used medium-scale integrated TTL logic.In 1975, Intersil cast the PDP-8 CPU design into an integrated processor, the Intersil 6100 (second-sourced by Harris). DEC never used this microprocessor in a PDP to my knowledge, but in their "DECmate" early personal computers.https://en.wikipedia.org/wiki/Intersil_6100

author: nad007007
author_rank: Contributor
timestamp: March 08, 2019, 09:56:10 am
content: Very nice.

author: fanOfeeDIY
author_rank: Unknown
timestamp: April 10, 2019, 02:01:29 pm
content: The 12 bits one chip cpu what I could come up in mind is this chip.I think it was used on Ford for the fuel injection ecu.http://toshiba-mirai-kagakukan.jp/en/learn/history/ichigoki/1975digital_controller/index.htmI remembered this when I saw some tv program long time ago.

author: TheEPROM9
author_rank: Frequent Contributor
timestamp: April 14, 2019, 07:09:13 pm
content: Loving the chip collections

author: chris_leyson
author_rank: Super Contributor
timestamp: April 14, 2019, 07:52:29 pm
content: The Cinematronics CPU was 12-bit with 8-bit instructions. All TTL (mostly)