Buying Older Parts From EBay - Page 1
Forum section: electronics / general

author: admiralk
author_rank: Regular Contributor
timestamp: September 01, 2019, 12:43:48 am
content: I am currently putting together a project, basically a homebrew 8088 computer, and eBay is virtually the only source for parts. I have noticed a few things that would apply to buying pretty much any component from eBay, although I am talking about older parts here.The first thing is knowing your part number. D8088 or D8086 is a ceramic package, yet probably half the items claiming those numbers are PDIP. This applies to pretty much any chip from the era. While there should be nothing wrong with plastic packages, that is legitimate, it should have a P prefix. In this case "vintage" and "collectable" are thrown about freely with no regard to what is actually being sold. Even if the parts are legitimate, they are being offered for a huge premium. To be fair, some sellers do mention they are selling clones. I would be more inclined to buy from them than the BSers. One thing I find interesting is the mythical 8088-1. You can find fan sites that list it, without any image. While the 8086 datasheet clearly states an 8086-1 version, the 8088 datasheet only mentions the 8088 and 8088-2 as the only versions.Those are the two main things I have run across so far, I am sure there are others. Please do not attack China on these discrepancies, they come from sellers all over the world.Anyway, just voicing some of my frustrations from looking for sources to parts over the last couple days.

author: scatterandfocus
author_rank: Regular Contributor
timestamp: September 01, 2019, 01:04:48 am
content: On a more serious note, I am glad that classic, well made, and repairable gear is still available on the used market. All of this stuff could be sitting in landfills right now, but the high quality of it keeps much of it in re-circulation.Oops, posted in the wrong thread.

author: Towger
author_rank: Super Contributor
timestamp: September 01, 2019, 01:08:09 am
content: I believe NASA bought up all the 8088 stock years ago, at they were used in various space shuttle systems.

author: admiralk
author_rank: Regular Contributor
timestamp: September 01, 2019, 01:39:09 am
content: That is interesting, and I might have even heard about it before.https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.html] https://www.nytimes.com/2002/05/12/us/for-parts-nasa-boldly-goes-on-ebay.htmlI am pretty sure the shuttles have been scrapped for some time though. "NOS" would not be unreasonable, although that also brings a premium, just as military parts do. Misguided, or not, one of the reasons I am interested in CDIPs is I expect them to be more hardy, or more likely to be working now. At ~ $3.00 compared to $0.30, for logic I am happy to use PDIP.

author: RomDump
author_rank: Regular Contributor
timestamp: September 01, 2019, 01:50:36 am
content: Quote from: admiralk on September 01, 2019, 12:43:48 amNot true.Jameco

author: admiralk
author_rank: Regular Contributor
timestamp: September 01, 2019, 03:41:10 am
content: I never said there where not alternatives, butQuoteNot that it matters much, I would also like an 8088-2. The PPI (8255?) chip only goes up to 5 MHz, so a slightly higher speed does not mean a lot. But then again I am dealing with a 16 bit architecture with an 8 bit bus. That reminds me of another discrepancy in the naming that is not related to eBay. The -5 version only goes up to a 4 MHz bus, while the -2 handles 5 MHz. If anything, you would think it would be the other way around.

author: jfiresto
author_rank: Frequent Contributor
timestamp: September 01, 2019, 08:49:05 am
content: I wanted some CD4538P (PDIP) one-shots to test a design, which are a little hard to get, as distributors tend to substitute its successor, the CD14538P. I picked up ten new/old stock V4538's off ebay.de, that were made in the former East Germany some 30+ years ago. They still look like new.

author: jfiresto
author_rank: Frequent Contributor
timestamp: September 01, 2019, 10:46:28 am
content: For those that are interested, I found a couple reliability surveys from1997and2008(both PDFs) of the long term storage of plastic encapsulated microelectronics. I bet my old, 4000A-series PDIP CMOS is still good.

author: Gyro
author_rank: Super Contributor
timestamp: September 01, 2019, 10:56:20 am
content: From my stock, old 4000 series parts are still good long term... and still useful forverylow current simple battery operated tasks.For some reason, 74Cxx (Not HC and other more modern families) parts are as flaky as hell. It must have been something (non manufacturer specific) in the process. Luckily they don't come up that often, but are sometimes to be found in '70s-early '80s era test gear.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 01, 2019, 03:15:51 pm
content: https://en.wikipedia.org/wiki/NEC_V20https://www.ebay.ca/sch/i.html?_odkw=nec+v20&_osacat=0&_from=R40&_trksid=m570.l1313&_nkw=nec+v20&_sacat=0

author: admiralk
author_rank: Regular Contributor
timestamp: September 01, 2019, 06:28:08 pm
content: That reliability report looks interesting, I just skimmed the newer one.I did consider the V20, but am going with an 8088-2. If I decide to do a 16 bit build later, I will probably look into the V30.

author: admiralk
author_rank: Regular Contributor
timestamp: September 01, 2019, 09:15:04 pm
content: Speaking of datasheets, I noticed that many of the datasheets for various parts are taken from one large one.exampleDoes anyone know what the large one is?

author: Canis Dirus Leidy
author_rank: Regular Contributor
timestamp: September 02, 2019, 01:07:04 pm
content: Quote from: admiralk on September 01, 2019, 09:15:04 pmSomewhere here:http://bitsavers.informatik.uni-stuttgart.de/components/intel/_dataBooks/

author: admiralk
author_rank: Regular Contributor
timestamp: September 02, 2019, 08:50:39 pm
content: Thank you, that was more than I was looking for.