UVPROM  - Page 1
Forum section: electronics / general

author: veedub565
author_rank: Frequent Contributor
timestamp: May 10, 2023, 04:56:25 pm
content: Hope this is the right part of the forum for this. I have a HP 8341B Signal Generator with four UVPROM's containing the firmware on the processor board. The firmware is an old version and I want to update it. I want to retain the old UVPROM's so I still have a good copy of the old firmware.The UVPROMS's are AMD AM27256-1DC and long since obsolete now.Couple of questions,1. Is there a suitable modern alternative ?2. Is it worth buying used UVPROM's ?

author: Andy Watson
author_rank: Super Contributor
timestamp: May 10, 2023, 05:36:03 pm
content: I've purchased a few batches of EPROMS from ebay without any problems. All of them used. Note, you'll probably want a UV eraser to make sure that theyr're blank.Alternatively, take a copy of the erpoms that you have and then re-program them.

author: veedub565
author_rank: Frequent Contributor
timestamp: May 10, 2023, 05:46:07 pm
content: Thanks Andy, got a Stag prom eraser available to me to wipe them with.

author: Peabody
author_rank: Super Contributor
timestamp: May 10, 2023, 06:10:59 pm
content: They appear to still be available. Jameco has a few hundred in stock, which I assume are new.But I wonder if an AT28C256 EEPROM would work. But the old UV version may be cheaper and easier to find.

author: srb1954
author_rank: Super Contributor
timestamp: May 10, 2023, 08:14:14 pm
content: Quote from: veedub565 on May 10, 2023, 04:56:25 pmIf you are doing a simple S/W update and don't need to repeatedly erase and reprogram parts you should also consider OTP (one-time-programmable) parts e.g. Microchip AT27C256R-70PU. These are still available new from reputable distributors and are somewhat cheaper as they are packaged in a standard plastic DIP package rather than the expensive windowed ceramic package.

author: westfw
author_rank: Super Contributor
timestamp: May 11, 2023, 12:05:47 am
content: You can still buy 27c256 EPROMs (modulo current chip shortages.)the OTP versions are pretty cheap.a 5V parallel EEPROM or FLASH chip should work, too. And probably 27c512s or equiv, which might be easier to find.

author: veedub565
author_rank: Frequent Contributor
timestamp: May 12, 2023, 03:44:10 pm
content: Thanks for the suggestions, I've ordered some used ones with the same part number. I'll erase those and program with the new firmware, see how it goes.

author: mon2
author_rank: Frequent Contributor
timestamp: May 14, 2023, 12:57:39 am
content: https://www.jameco.com/z/AM27256-1DC-Advanced-Micro-Devices-EPROM-UV-256K-32Kx8-8-Bit-200ns-5V-DIP-28_2303055.html

author: veedub565
author_rank: Frequent Contributor
timestamp: May 14, 2023, 06:52:15 pm
content: problem with Jameco is shipping to the UK, $30 shipping plus import duty.

author: veedub565
author_rank: Frequent Contributor
timestamp: May 27, 2023, 01:06:14 pm
content: Well the UVPROMS from EBAYfinallyarrived after a fortnight. I've been waiting on those so I can crack on with updating my 8341B with the latest firmware. So you can imagine my annoyance at finding that the clucking tw*t of a seller has stuck the IC's into nothing more than plastic packing foam done up with sellotape. Couldn't have done any more to blow the sh1t out of them with ESD if they'd triedSo that was a total waste of time and money. Going to explore some of the other options mentioned in this thread.

author: Peabody
author_rank: Super Contributor
timestamp: May 27, 2023, 02:01:52 pm
content: I remember the UV parts as being pretty tolerant of abuse like that. Perhaps you should at least try them to see if they will program.

author: veedub565
author_rank: Frequent Contributor
timestamp: May 27, 2023, 04:17:58 pm
content: Yeah the older stuff like that is more tolerant then the more modern stuff. I will give them a try, It's not ideal though, and a little frustrating. Such is the vagaries of EBAY I suppose.

author: m k
author_rank: Super Contributor
timestamp: May 27, 2023, 07:31:35 pm
content: It's very irritating when people are dealing with these things seemingly without any idea of ESD.Legendary is a situation where seller has opened the package and placed components on what ever surface, beside the package.One other thing, I don't understand this ROM access time uncertainty, it's just a memory.Maybe it's an understanding of not available, it's not complete, something is always available.If you upgrade a computer memory you're checking how fast replacement is still accessed faster.Last time I bought 256k 28-series EEPROMs.They are also drop in replacements for 64k and 128k of 27-series.Of course for non authentic cases only.

author: veedub565
author_rank: Frequent Contributor
timestamp: June 16, 2023, 04:45:03 pm
content: Well I got around to erasing these chips, 1hr with a Stag prom eraser. My friend was going to program them for me, but it turns out his Dataman 48UXP doesn't list that device. I think he said he'd have to spend £150 to get a license or something, not worth it.Any suggestions ?Dataman 48Pro2 does list that device, but really expensive to buy.I'm looking to see if there are any businesses nearby that would program them for me.Or I could use one of the other IC's previously mentioned, and maybe a cheaper prommer would work.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: June 17, 2023, 02:00:56 am
content: Quote from: veedub565 on June 16, 2023, 04:45:03 pmMy EEtools programmer says this about those chipsManufacturer:AMD, Device name:Am27256Package Info.:DIP28, Organization:8000h x 8 bit, Adapter name:None, Manufacturer ID.:0001, Device ID.:0004, Algorithm:Quick, Vcc pin(s):28, Gnd pin(s):14, Vpp pin:1, Vccp:6.25V, Vpp:12.75V, Tpwp:100usSo you may be able to select a same-algorithm device ?

author: jonsikul
author_rank: Contributor
timestamp: July 09, 2024, 02:36:05 pm
content: Did you ever get around to finish the task? If yes, how did it work out?

author: veedub565
author_rank: Frequent Contributor
timestamp: July 15, 2024, 04:27:00 pm
content: Yeah I cheated and paid a professional to program them for me. Worked out fine

author: josip
author_rank: Regular Contributor
timestamp: July 15, 2024, 06:44:13 pm
content: Just note that I erased mine (original owner) by sun lite this spring in few weeks. Was not in hurry.

author: coppice
author_rank: Super Contributor
timestamp: July 15, 2024, 06:53:08 pm
content: Quote from: josip on July 15, 2024, 06:44:13 pmInteresting. Many years ago we put a couple of UV EPROMs out in the sun to see how long they would take to fail a CRC check. After a few months we gave up. This was in London, where rust is a bigger issue than sunshine, but this was our experience.

author: m k
author_rank: Super Contributor
timestamp: July 15, 2024, 07:44:43 pm
content: I bought an UV-C LED, can't remember the wavelength but close to optimal it was.Erasing took some minutes.Mini-Pro was checking on the fly how the thing advanced and same stubborn bits were the final resistance every time.

author: Postal2
author_rank: Frequent Contributor
timestamp: July 15, 2024, 11:02:02 pm
content: I don't know about uvc-led, must be hi-power led for erase (with passive cooler). I use uv-lamp. Need to bind with wire uv-chip directly to lamp tube. After 2 hours no change. Need 8..10 hours to erase. My lamp is exactly as photo, but wavelength is 120 nm and much ozone produced. Power of my lamp is 20W.

author: coppice
author_rank: Super Contributor
timestamp: July 15, 2024, 11:19:45 pm
content: Quote from: Postal2 on July 15, 2024, 11:02:02 pmA LED seems ideal for this job, when you only need to erase a single chip. The target area is small, like a LED. The traditional UV tubes used in EPROM erasers wasted 99% of the light.

author: Postal2
author_rank: Frequent Contributor
timestamp: July 16, 2024, 12:01:15 am
content: Quote from: coppice on July 15, 2024, 11:19:45 pmI agree, if you have such - bring your experience with exact data about led and other.

author: retiredfeline
author_rank: Frequent Contributor
timestamp: July 16, 2024, 12:13:28 am
content: You can buy 3W 10V UV disinfection E17 base bulbs from eBay for about $5 that put out the right wavelength.

author: Postal2
author_rank: Frequent Contributor
timestamp: July 16, 2024, 12:49:34 am
content: Quote from: retiredfeline on July 16, 2024, 12:13:28 amSigned as no ozone with 250 nm wavelength. Bind with wire to chip and wait. Success will be, but I don't know how long wait.I erased M27C512 from ST 4 pcs with my lamp at 8..10 hours.QuoteNow, of course, I bought a lot of W27C512 and W27E512 for use instead.

author: Andy Chee
author_rank: Super Contributor
timestamp: July 16, 2024, 04:44:23 am
content: Quote from: Postal2 on July 16, 2024, 12:01:15 amThey do exist:https://www.epigap-osa.com/wp-content/uploads/2024/02/EOLD-255-012.pdfBut I agree, germicidal fluorescent tubes are cheaper and more readily available.My eraser is like this one, but without a timer and LED countdown:https://www.digitalfriends.ca/wp-content/uploads/2021/06/20210617_101513-768x1024.jpgIt uses a germicidal tube.

author: aeg
author_rank: Regular Contributor
timestamp: July 16, 2024, 07:14:05 am
content: Quote from: Postal2 on July 15, 2024, 11:02:02 pmYikes! A 254nm, 2-watt lamp at point blank range will erase most EPROMs in less than two minutes.

author: Postal2
author_rank: Frequent Contributor
timestamp: July 16, 2024, 07:19:40 am
content: Quote from: aeg on July 16, 2024, 07:14:05 amThis is for those who can't count. You can easily recalculate power and time according to the datasheet of M27C512.It is suitable if the emitted energy is 2 watts, not consumed.Yes, I found it. For a UVC254 E17 3W lamp, 90 sec erasing has been tested in practice.This lamp has a huge UV power - 160 mW! If the space around it is folded into 1 sq. cm, then the erasing time is 100 seconds.I probably made a mistake when calculating the power before. Data for other lamps show that at a power of 4 W the radiation is ~100 µW.Nevertheless, I believe that if there is a lamp, even if it is not suitable, but it erases UVPROM in 10 hours, then that is enough for me, I am not in a hurry.

author: stj
author_rank: Super Contributor
timestamp: July 17, 2024, 12:13:40 pm
content: sunlight will probably erase eproms a lot faster than people think,*something* has happened to the ionosphere recently and we are getting a lot more UV hiting us - including UVC which is not officially supposed to be happening!i am in London and it's bleaching the roadsigns so the reds are turning yellow!!

author: coppice
author_rank: Super Contributor
timestamp: July 17, 2024, 03:27:31 pm
content: Quote from: stj on July 17, 2024, 12:13:40 pmIts doesn't take UVC to bleach things. UVC doesn't pass through conventional glass windows very well, but curtains have always bleached in colour, and crumbled, quite well in London when facing the sun for a large part of the day.