Flash replacement for EPROM - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: April 13, 2023, 02:02:51 am
content: I've been making these particular boards in one form or another for about 25 years, and they use a 1Mx8 EPROM that contains 128 lookup tables each 8K long. It's time to get into the 21st century. Trouble is, using flash is a whole lot more complicated than EPROMs. Looking at the data sheet I have no idea where to start. What would be really simple is a daughter board that could plug into the existing 32 pin DIP socket. Some level translation needed because the main board is 5V. And maybe converting parallel to serial and vice versa, depending on the actual chip. And some means to program it before it gets plugged into the main board.Can anyone give me some pointers. I have no idea where to even start.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 13, 2023, 02:53:05 am
content: Quote from: Circlotron on April 13, 2023, 02:02:51 amI'm not sure about "converting parallel to serial and vice versa" that's never going to be practical, but you might find packages other than DIP32 are easier to apply to a daughter board.That said, you can still buy DIP32 EPROMs eg 27H010 from Digikey, or AT27C0x0 from Mouser etc.You can use FLASH parts, if you pgm externally and simply tie WE# high.Parts like SST39SF010A-70-4C-PHE look to be active and stocked and 1/2/4Mb can all fit into DIP32, so that gives you many choices, without needing a daughter card.For a while Winbond made MTP versions of their W27C010/W27C020 etc, sometimes called W27E010/W27E020, and those seem to show up on Aliexpress.https://www.aliexpress.com/item/1005003166003152.html

author: Circlotron
author_rank: Super Contributor
timestamp: April 13, 2023, 03:17:28 am
content: Okay. I'm currently using a M27C801. And yeah, I did find some parallel flash. Not sure what I was thinking. The biggest hurdle may yet be programming, but what you have said is a start.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 13, 2023, 03:42:49 am
content: Quote from: Circlotron on April 13, 2023, 03:17:28 amAhh - looks like you can still buy 27C801 ok, and AT27C080 too..

author: fchk
author_rank: Frequent Contributor
timestamp: April 14, 2023, 06:41:40 am
content: https://www.digikey.com.au/en/products/detail/microchip-technology/SST39SF020A-70-4C-PHE/2297831Currently 1957 in stock.fchk

author: westfw
author_rank: Super Contributor
timestamp: April 14, 2023, 08:26:43 am
content: QuoteSST39SF020A-70-4C-PHEWhy would you think that a 2MbitFlash chip can replace a 1MbyteEPROM ?There are a bunch of 8Mbit parallel flash chips, but I don't see any in DIP packages. And the available packages look like they would be pretty tricky to put onto an adaptor PCB...

author: peter-h
author_rank: Super Contributor
timestamp: April 14, 2023, 10:18:31 am
content: How do people program these nowadays?Data IO went bust about 20 years ago. I still have their Chiplab programmer which just keeps running; one product I've been making since 1995 uses an H8/323 which is OTP EPROM on chip. 27C256 lookalike.Actually there is a huge choice of old 4 digit priced programmers on Ebay, going for practically nothing. You may need a winXP machine, but that's ok.https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p3814320.m570.l1313&_nkw=eprom+programmer&_sacat=0

author: wek
author_rank: Frequent Contributor
timestamp: April 14, 2023, 10:39:18 am
content: Quote from: peter-h on April 14, 2023, 10:18:31 amWell, the EPROMs are kind of a relic, but if you for some reason want a current solution, thenhttps://www.elnec.com/en/device/Atmel/AT27C080/Yes, I am a patriot. You can buy Dataman.JWPS.DataIOappears to be up and kicking, although they don't appear to be making single-chip desktop programmers anymore.

author: peter-h
author_rank: Super Contributor
timestamp: April 14, 2023, 11:41:26 am
content: QuoteThat's a lot better than selling heavy stuff to the USSRDataman also started at the same time as I started my current business: 1991. And it is one of the few electronics companies from that time who are still going in present form.

author: woofy
author_rank: Frequent Contributor
timestamp: April 14, 2023, 01:43:37 pm
content: Quote from: peter-h on April 14, 2023, 10:18:31 amDataman have been around seemingly forever, and still manufacture professional grade programmers.I still have an old parallel port version of this one, somewhere.https://www.dataman.com/dataman-48uxp-universal-programmer.htmlHaven't used it in years though.

author: abyrvalg
author_rank: Frequent Contributor
timestamp: April 14, 2023, 05:41:47 pm
content: We use Elnec BeeProg2 in arcade hw restoration projects and it is great, supporting both ancient things like bipolar PROMs found on original Ghosts’n’Goblins pcbs and multimegabyte flashes from Sega Lindbergh.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 14, 2023, 08:22:38 pm
content: Quote from: peter-h on April 14, 2023, 10:18:31 amThere are also Chinese programmers, the TL866 and descendants are still active - AliXpress says sub US$50, decent for a parallel pgmr that supports 27C801 & AT27C080.http://www.autoelectric.cn/

author: peter-h
author_rank: Super Contributor
timestamp: April 15, 2023, 02:42:30 pm
content: Would you trust these to support the algorithms correctly?Some were not too simple, and I would put money on the chinese just listing 100,000 devices and testing only 2 of themWhereas some 20 year old programmer, $2000 when new, will probably do it right.Old test gear can be fantastic value for money.