Good source for eproms?
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one. What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom. Thanks, -- Jason Perkins
Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM. Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find. -Ian On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure. I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them. -Dave On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote:
Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
The EPROM on the drive now doesn't have a window. I thought that means it's only one time programmable? Dave, I'll drop you a line off-list. Thanks for the offer! -J On Tue, May 24, 2016 at 11:54 PM, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure.
I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them.
-Dave
On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote:
Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
-- Jason Perkins 313 355 0085
On May 25, 2016, at 7:14 AM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote: The EPROM on the drive now doesn't have a window. I thought that means it's only one time programmable? Dave, I'll drop you a line off-list. Thanks for the offer! -J On Tue, May 24, 2016 at 11:54 PM, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure.
I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them.
-Dave
On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote: Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
-- Jason Perkins 313 355 0085 -------------- I have been told by an electronics engineer that many PROMs without windows are structurally/electrically the same as UVEPROMs but just don't have windows. This is done for manufacturing cost savings, apparently the window is an expensive feature (I think they are Quartz). If a manufacturer just needs to program once and not erase, they use windowless ICs. A blank/corrupt one might have "failed" (gotten erased but still functional like Ian said) because of some long term radiation exposure (possibly just background radiation), and then might be able to be reprogrammed. Whether or not it is worth the trouble is another question. Another type of ROM is "masked" meaning that the data/program is etched into the silicon in the chip manufacturing process and is permanent. These offer a further cost savings to manufacturers who are doing large enough volume. I suspect that this type is is less common in older/low volume models. Just some ROM background that I picked up over the years, I hope it was helpful or interesting. Chris
Yup, "OTP" EPROMs. There are microcontrollers of that sort as well, same chips in different packaging. Quartz windows and ceramic packages (which are essentially required for quartz windows) are expensive, whole plastic is cheap. The idea is to develop and debug on erasable EEPROMs, then move to OTP for production with no PCB changes. Of course most of that has been supplanted by flash memory technologies now, but EPROMs are still around. -Dave -- Dave McGuire, AK4HZ New Kensington, PA On May 25, 2016 7:14:46 AM Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
The EPROM on the drive now doesn't have a window. I thought that means it's only one time programmable?
Dave, I'll drop you a line off-list. Thanks for the offer!
-J
On Tue, May 24, 2016 at 11:54 PM, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure.
I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them.
-Dave
On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote:
Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
-- Jason Perkins 313 355 0085
On 5/26/2016 1:41 PM, David Riley via vcf-midatlantic wrote:
On May 26, 2016, at 00:48, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yup, "OTP" EPROMs. I think that's just called a "PROM". :-)
- Dave
No, from what I understand of the usual usage of terms, PROMS are the bipolar/fusible link parts like 82s137, MMI6301, etc. These can be open collector or tri-state. OTPROMs aka OTP EPROMs are floating gate 2764/27128/etc EPROMs with no window, so they can't be erased with UV light (though, as we can see here, age can still cause them to become slowly erased). Mask ROMs are the 2364/23128/etc parts which are mask programmed at the chip fab, and never lose their contents unless they lose their smoke. -- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
On 05/26/2016 01:56 PM, Jonathan Gevaryahu via vcf-midatlantic wrote:
OTPROMs aka OTP EPROMs are floating gate 2764/27128/etc EPROMs with no window, so they can't be erased with UV light (though, as we can see here, age can still cause them to become slowly erased).
They can be erased with X-rays. EPROMs were originally designed to be erased that way. There are problems with that approach, however. (hence the move to UV) -Dave -- Dave McGuire, AK4HZ New Kensington, PA
On May 26, 2016, at 1:56 PM, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
On 5/26/2016 1:41 PM, David Riley via vcf-midatlantic wrote:
On May 26, 2016, at 00:48, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Yup, "OTP" EPROMs. I think that's just called a "PROM". :-)
- Dave
No, from what I understand of the usual usage of terms, PROMS are the bipolar/fusible link parts like 82s137, MMI6301, etc. These can be open collector or tri-state.
Well, a PROM is a ROM that can be Pd, but not Ed. :-) The underlying technology doesn't matter, though the interpretation of the term may be a little loaded with assumed meaning.
OTPROMs aka OTP EPROMs are floating gate 2764/27128/etc EPROMs with no window, so they can't be erased with UV light (though, as we can see here, age can still cause them to become slowly erased).
Ah, that makes a little more sense. I hadn't thought about the X-ray erasure mode of operation. It's not really OTP then, though.
Mask ROMs are the 2364/23128/etc parts which are mask programmed at the chip fab, and never lose their contents unless they lose their smoke.
Or unless electromigration takes out a path or two, but that's a much longer process and akin to losing the magic smoke. - Dave
On May 26, 2016, at 2:29 PM, David Riley via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Mask ROMs are the 2364/23128/etc parts which are mask programmed at the chip fab, and never lose their contents unless they lose their smoke.
Or unless electromigration takes out a path or two, but that's a much longer process and akin to losing the magic smoke.
I've read about this being a major issue for Mostek mask ROMs. David
Is "metric assload" am official Department of Weights and Measures unit of measurement? On May 24, 2016, at 11:54 PM, Dave McGuire via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote: Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure. I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them. -Dave
On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote: Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
It is in the UK but I am not too sure if its differs from an imperial assload or if a US Imperial assload is different from a UK imperial assload. Judging by the shorts sported by some US tourists recently observed at a museum in the UK , unlike pints, the US version is larger. Dave G4UGM p.s. If any one over this side needs proms I have a few, and can program some of the more common variety.
-----Original Message----- From: vcf-midatlantic [mailto:vcf-midatlantic- bounces@lists.vintagecomputerfederation.org] On Behalf Of chrisjpf33--- via vcf-midatlantic Sent: 25 May 2016 12:30 To: vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> Cc: chrisjpf33@gmail.com Subject: Re: [vcf-midatlantic] Good source for eproms?
Is "metric assload" am official Department of Weights and Measures unit of measurement?
On May 24, 2016, at 11:54 PM, Dave McGuire via vcf-midatlantic <vcf- midatlantic@lists.vintagecomputerfederation.org> wrote:
Yes. The problem with EPROMs forgetting their contents is charge leakage from the floating gates, not chip failure.
I have a metric assload of EPROMs (literally thousands) of nearly every type, especially the really common ones like 2764s, if anyone needs them.
-Dave
On 05/24/2016 11:52 PM, Ian Primus via vcf-midatlantic wrote: Even if an EPROM has gotten corrupted, the chip itself should still be fine. Just erase and reprogram. I've yet to have a problem with doing this, it's quite rare to have a dead EPROM.
Almost every EPROM I have has been scavenged from some sort of junk board or another. 2764's and 2732's are quite common, should not be hard to find.
-Ian
On Tue, May 24, 2016 at 11:22 PM, Jason Perkins via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jason Perkins
-- Dave McGuire, AK4HZ New Kensington, PA
Be sure to dump the existing eprom first just to make sure that it is dead. We've lost more firmware revisions than I can count (and yes, even old/obsolete versions need to be preserved) by people just wiping and reburning eproms without checking to see whether the version on it originally was known or not. On 5/24/2016 11:22 PM, Jason Perkins via vcf-midatlantic wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
Johnathan, Don't worry, that's the first thing I did. I also found that after a couple reads a few bits had flipped! On Wed, May 25, 2016 at 7:27 AM, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Be sure to dump the existing eprom first just to make sure that it is dead. We've lost more firmware revisions than I can count (and yes, even old/obsolete versions need to be preserved) by people just wiping and reburning eproms without checking to see whether the version on it originally was known or not.
On 5/24/2016 11:22 PM, Jason Perkins via vcf-midatlantic wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
-- Jason Perkins 313 355 0085
Hmm. dump it 5 or 6 times, and note what addresses/bits are unstable. Also, if your programmer supports it, try dropping the VCC voltage from 5v to 4.95 or 4.90v, this often helps with decayed-floating-gate (aka "bit-rotten") eproms, since it affects the voltage threshhold for the '1 vs 0' comparator per-bit. On 5/25/2016 9:00 AM, Jason Perkins via vcf-midatlantic wrote:
Johnathan,
Don't worry, that's the first thing I did. I also found that after a couple reads a few bits had flipped!
On Wed, May 25, 2016 at 7:27 AM, Jonathan Gevaryahu via vcf-midatlantic <vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
Be sure to dump the existing eprom first just to make sure that it is dead. We've lost more firmware revisions than I can count (and yes, even old/obsolete versions need to be preserved) by people just wiping and reburning eproms without checking to see whether the version on it originally was known or not.
On 5/24/2016 11:22 PM, Jason Perkins via vcf-midatlantic wrote:
I'm trying to get a Plus HardCard going again. Like many the ROM has forgotten some of its bits so I want to try installing a freshly flashed one.
What's a good source for 7264s? Is it worth trying to get used ones on eBay? While I'm at it I'd like to track down a 2732 for an Apple ProFile formatting rom.
Thanks,
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
-- Jonathan Gevaryahu jgevaryahu@gmail.com jgevaryahu@hotmail.com
participants (9)
-
Bill Sudbrink -
chrisjpf33＠gmail.com -
Dave McGuire -
Dave Wade -
David Riley -
David Ryskalczyk -
Ian Primus -
Jason Perkins -
Jonathan Gevaryahu