WANTED: Old DIP-28 EPROM Chips - Page 1
Forum section: electronics / general

author: Halcyon
author_rank: Unknown
timestamp: November 03, 2017, 08:47:28 am
content: Hi guys,As you may or may not be aware, rebuilding vintage computers is a huge hobby of mine and I've recently been helping a few mates out with similar projects. I've got all sorts of cards, cables and parts that I've collected over the years. Some I've kept for myself and others I've given away to those who appreciate vintage technology.I've recently helped a friend out with burning some ROMs for his Acorn computers he has and am running really low on old windowed (UV erasable) EPROMs. If anyone has any they can part with (I'm happy to pay), especially for any M27C128 types, it would be greatly appreciated!

author: dexters_lab
author_rank: Unknown
timestamp: November 03, 2017, 09:10:23 am
content: just checked and i don't have any 27c128, all most of mine are c256 or c512i'll check with someone i know, they did have some NOS tubes of eproms but i don't recall exactly what they were

author: wraper
author_rank: Unknown
timestamp: November 03, 2017, 10:55:37 am
content: You can get M27C128 on ebay. However many of them had some Chinese magic applied to them. Old marking removed and new one applied. So if silicon die looks the same, it's the same IC, however don't count on date code and speed grade.

author: ebclr
author_rank: Super Contributor
timestamp: November 03, 2017, 11:05:06 am
content: Isn't exactly what you looking for but, is what will solve your problemhttp://ww1.microchip.com/downloads/en/DeviceDoc/20005022C.pdfIf you wanna the old stuffhttps://s.taobao.com/search?q=M27C128&type=p&tmhkh5=&spm=a21wu.241046-global.a2227oh.d100&from=sea_1_searchbutton&catId=100

author: perieanuo
author_rank: Frequent Contributor
timestamp: November 03, 2017, 11:48:21 am
content: Quote from: Halcyon on November 03, 2017, 08:47:28 amWhere do you live?Envoyé de mon HUAWEI NXT-L29 en utilisant Tapatalk

author: legacy
author_rank: Super Contributor
timestamp: November 03, 2017, 12:23:29 pm
content: Quote from: dexters_lab on November 03, 2017, 09:10:23 amas mine, plus a lot of C010, and a couple of C020(which is the biggest UV_ROM I have, LOL)

author: macboy
author_rank: Super Contributor
timestamp: November 03, 2017, 02:43:33 pm
content: I came acrosshttp://www.epromman.com/the other day, on a retro arcade game forum. Worth a try.

author: guido
author_rank: Regular Contributor
timestamp: November 03, 2017, 06:01:47 pm
content: I'll be going to a clearance sale of electronic components in december or january. Three rooms which were filled to the roof with equipment and components, which we have been plundering for the last years. So all the good stuff hast mostly gone, allthough you can still find new gems under all of the remaining stuff. There will be one last clearance sale, where prices will be even lower than usual. After that it's gone.One of the thing you findeverywhereare eproms. Many of them, really really MANY of them. I have collected all of the non standard EPROMs for my own repairs. But 27128 i consider bog standardI think there are plenty of them around at the site. Sent me a PM and i will see what i can do. Shipment would be the cost driver.I have Acorn Atom machines myself.

author: Halcyon
author_rank: Unknown
timestamp: November 03, 2017, 11:06:54 pm
content: Quote from: wraper on November 03, 2017, 10:55:37 amYes I know, I'd rather avoid anything that might have been 'tampered' with and go for collections sitting in EE's workshops somewhere.Quote from: perieanuo on November 03, 2017, 11:48:21 amSydney, Australia.Quote from: macboy on November 03, 2017, 02:43:33 pmThanks, looks quite reasonable.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: November 04, 2017, 12:02:06 pm
content: You could probably use a 27256 in place of a 27128. Only difference is 27128 has /pgm on p27, /ce on 20, /oe on 22. 27256 has /ce & /pgm on 20 and 27 is now A14. Once programmed it would probably work, just not addressing the upper half of the chip. The whole family of eproms were basically socket compatable.Ken

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2017, 02:39:23 pm
content: Correct on the common family pinout, many old boards had a jumper so you could put a 24 pin device in, when you had firmware below 64k in size and thus could use any 2764 or greater size, whichever was cheaper. Many boards also had select jumpers as the developers also wanted to have the flexibility to use cheaper larger size proms as they got cheaper. I have seen many where, as the size stayed the same, the actual chip inside the window shrank, so you get a 27128 at the early stage filling the entire large window, but later generation ones with lower program voltages being a very much smaller die. That is why you get ID strings inside many modern proms, so the programmer can set up accordingly to use the right algorithm ( aside from the voltage being correct and then 50ms per byte as default) for fast programming.

author: perieanuo
author_rank: Frequent Contributor
timestamp: November 04, 2017, 05:46:15 pm
content: Quote from: perieanuo on November 03, 2017, 10:48:21 PMWhere do you live?Sydney, Australia.Nice!In this case it isn't worth to send you some eeproms, even at 1 euro/piece, I think you get them cheaper on ebay.I'm from France.Worst, my godfather lives in Sydney but I lost contact...Regards,Pierre

author: FrankBuss
author_rank: Unknown
timestamp: November 04, 2017, 05:58:06 pm
content: Recently I used an AT27C256 for a DIY Vectrex cartridge:They are really cheap:https://www.digikey.de/short/qtwm1dOnly one time programmable, can't be UV erased, but doesn't matter much for this price and you can emulate most old computer systems anyway on a PC before burning the ROM. My TL866 could burn it with no problems in seconds. The pinout is nearly the same as for the 27C128 EPROMs, you might only need to tie A14 to GND, or VCC, if you burn the content in the upper half or copy it.

author: IconicPCB
author_rank: Super Contributor
timestamp: November 04, 2017, 11:41:44 pm
content: I thought i had some in th bottom of the junk bin.Turns out they are d8748 micros.

author: Sjokolade
author_rank: Regular Contributor
timestamp: November 05, 2017, 01:00:43 am
content: Found these at the dump some time ago, useful for anyone here ?

author: hermit
author_rank: Frequent Contributor
timestamp: November 05, 2017, 06:01:18 am
content: I have some M27C256B. Still in the tube the came in originally. Let me know if you don't find something better.

author: SeanB
author_rank: Super Contributor
timestamp: November 05, 2017, 06:37:55 am
content: I have a number of SEEQ eproms as well, will have ot check if the TL866 can program them, and if they still work after 30 years of storage.

author: max-bit
author_rank: Frequent Contributor
timestamp: November 05, 2017, 07:57:51 am
content: for sale these ICs?

author: carlstechshed
author_rank: Newbie
timestamp: November 08, 2017, 01:56:44 pm
content: I've got two tubes (24 ICs total) of AMD 27C128 EEPROMs.Date codes range from 1995-1998. They are all new-old-stock from an electronics company I cleared out.Let me know if you're interested