How do you know EEPROM chips are good

dl324

Joined Mar 30, 2015
9,331
I have never done a blank testing. so what do you mean?

I put the EPROM chips in a UV light eraser and set the timer to the datasheets of the EPROM chip which is about 15mins to not damage the cells. is this how you erase EPROM chips?
Yes and no. If you read the datasheet for the EPROMs, it probably gives you a typical exposure time for erase. Erase time will increase as the UV tube ages. It also depends on the distance from the EPROM to the tube and how clean the quartz window is.

A "good" EPROM programmer will verify erase and program margins. I have an old Stag programmer that I confirmed doesn't perform erase margin checking correctly. I stopped using it because I wasn't sure it programmed correctly. Now I use a hobbyist programmer and I verify margins manually.
Maybe I'm doing something wrong about the margins. I'm not really sure how to set up the margins
If you don't know about margins, then you don't know what you're doing and have to depend on your equipment doing it correctly. Some do, some don't. That's what my comment about all programmers not being equal meant.
The universal programmer software just has a button for reading, writing, erasing. I don't go into the settings and change anything or change the margins.
Some programmers let you change timings and voltages explicitly, some don't. For the ones that don't, you have to hope that they were designed properly.
How Should I set it up?
My crystal ball is at the cleaner. Even if you told me what programmer you have, I probably wouldn't know how to operate it.
Yes I know the difference, I was talking about EEPROMs at first about the read, write, checksum
I had to ask. When you were talking about EEPROMs, another poster was talking about EPROMs.
The EPROM chips I have latency failure problems. I think the UV light eraser is the problem and the write/erase cycling is the problem of the latency failures
If you're able to reprogram the affected EPROMs and they fail a short time afterwards, I'd question your programmer or how you're using it. A properly programmed EPROM should retain data for 10-20 years. An improperly programmed device could fail to work in the intended circuit immediately after programming. You, or your programmer, need to check erase and program margins explicitly (unless you're programming 2732 or older devices that were programmed open loop).
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
need to check erase and program margins
What settings do you set the erase margin? and program margins? mostly the universal programming software defaults or does this automatically

Some programmers let you change timings and voltages explicitly, some don't.
Yes i have notice this also. The universal programming software just defaults it and does this automatically, its fixed not changeable

Is there any other settings or things to look at for in a universal programming software?

If you read the datasheet for the EPROMs, it probably gives you a typical exposure time for erase.
Yes it says 15mins, but you have to have the correct UV light as the datasheets says.

I have an old Stag programmer that I confirmed doesn't perform erase margin checking correctly
f

So how do you know if the software program is not really checking correctly? how did you verify if the software is checking correctly the erase margin and program margins?
 

dl324

Joined Mar 30, 2015
9,331
What settings do you set the erase margin? and program margins? mostly the universal programming software defaults or does this automatically
As I've said *several* times, some programmers are good and some aren't. If you have one that isn't designed well and it doesn't let you adjust settings, then you have no control over how reliably devices are programmed.
Is there any other settings or things to look at for in a universal programming software?
Are you talking about software that can be used with multiple programmers? Or a programmer with self-contained software?
Yes it says 15mins, but you have to have the correct UV light as the datasheets says.
This is what I pulled from the first EPROM datasheet I opened:

"In order to clear all locations of their programmed contents, the device must be exposed to an ultraviolet light source. A dosage of 15 W seconds/cm^2 is required to completely erase the device. This dosage can be obtained by exposure to an ultraviolet lamp—wavelength of 2537 Å—with intensity of 12,000 µW/cm^2 for 15 to 20 minutes. The device should be directly under and about one inch from the source, and all filters should be removed from the UV light source prior to erasure."

It didn't mention that tube age also affects dosage. The bottom line is that either your programmer or you need to check erase margin. Most programming algorithms require a verify at 4.2V after programming. This has two benefits. It looks for problems with "program erase" and erase margin.

But the bottom line is that you erase until it's erased. Parts that don't erase after a reasonable amount of time should be treated as defective and discarded. Even if you don't do an explicit blank verify, the programmer should verify each byte as it's programmed and after programming the entire device; so defective devices should be caught.
So how do you know if the software program is not really checking correctly? how did you verify if the software is checking correctly the erase margin and program margins?
You find an independent method for verifying that your programmer is doing it correctly; or not.
 
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SamEricson

Joined Apr 25, 2015
196
Are you talking about software that can be used with multiple programmers? Or a programmer with self-contained software?
Self Contained, the software program comes with the universal programmer

Most programming algorithms require a verify at 4.2V after programming. This has two benefits. It looks for problems with "program erase" and erase margin.
Where do you find this 4.2volts? after your write the file to the EEPROM chip?

Why do you want to verify this 4.2 volts? what is this 4.2volts about

Where is the 4.2 volts coming from? the +VCC of the EEPROM chip?

The program margin and erase margin are dependent on the 4.2 voltage

When is it not 4.2 volts?
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
blank verify, the programmer should verify each byte as it's programmed and after programming the entire device; so defective devices should be caught.
I have never used the software to to verify the Blank, I'm guessing some programmers have this verifying the blanking

How do you verify each byte as it's programmed?

After programming, I just read the file again to make sure it's been stored and not corrupted. I never verified each byte , not sure how to do that
 

dl324

Joined Mar 30, 2015
9,331
Self Contained, the software program comes with the universal programmer
You look for one that works as intended.
Where do you find this 4.2volts? after your write the file to the EEPROM chip?
I was talking about EPROMs, it should have been clear from context if I was talking about EPROM or EEPROM.

EEPROMs have their own write/erase engines built in. You load data into a buffer and tell the device to program. It takes care of proper erase and program margins.

EPROMs on the other hand, have no built-in intelligence (unless you consider the FLASH devices that are marketed as EPROMs).
 

dl324

Joined Mar 30, 2015
9,331
The AMD datasheet I took the erase info from didn't mention the programming algorithm. I think with AMD you need to get another document or you need to copy Intel like they did...

Here's the algorithm for ST EPROMs. If you're programmer doesn't do something equivalent, it's one of the bad ones...
 

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Thread Starter

SamEricson

Joined Apr 25, 2015
196
Any Universal programmer can erase, read, write for EPROM or EEPROM chips

When you want to erase,read or write an EPROM chips , I have to look for the 4.2 volts in the software program?

Is the 4.2 volts the +VCC of the EPROM chip?

Plus I have to change the settings of the erase, read and write margins for EPROM chips in the software settings?
 

Brevor

Joined Apr 9, 2011
297
Is that supposed to contribute to the discussion in any way?
He means you are getting nowhere.
dl324, here is the situation, SamEricson fits the profile of someone who has been banned from this forum and several other forums several times. He keeps coming back under a different name. He asks the same questions over and over again in different ways and never resolves the problem. He eventually causes arguments among the forum members. This is why he is banned.

SamEricson, If you are not the person I am refering to please excuse me, but you don't seem to have any understanding of EEPROM's or EPROM (which ever it is that you have) You have not even told us exactly what IC you are using, which leads me to think you are the banned user I am refering to.
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
but you don't seem to have any understanding of EEPROM's or EPROM
I never said I did, that is why i'm trying to learn the correct way of erasing, reading, writing, checksum . etc. about EEPROM chips and ERPOM chips.

Most technicians I have worked with don't know either it seems.

dl324 is teaching and training me the right way because of issues i have been having.
 

dl324

Joined Mar 30, 2015
9,331
Any Universal programmer can erase, read, write for EPROM or EEPROM chips
One would hope that would be the case but, sadly, it isn't. I haven't seen a universal programmer that could erase an EPROM. The closest I've seen is a programmer that had a separate UV eraser. Then there's also the issue of a product doing what it's advertised to do. Sadly, that isn't guaranteed either...
When you want to erase,read or write an EPROM chips , I have to look for the 4.2 volts in the software program?
The algorithms used for programming EPROMs should be mentioned in the documentation.
Is the 4.2 volts the +VCC of the EPROM chip?
Yes. When an EPROM is blank checked, it has to be done at a voltage that is lower than the minimum VCC spec for the part; but it can't be arbitrarily low because the device still needs to function properly. Programming is performed at VCC=6-6.25V for devices larger than 32Kb. For devices 32Kb and smaller, programming was performed open loop and the goal was to change the threshold of programmed bits to about 8V. Devices after that used closed loop verification and only checked margin to the programming VCC. The 6V verify in the algorithm I posted doesn't make sense. If you do program verification at 4.2V and 6.25V, you guarantee it will work at any voltage in between.
Plus I have to change the settings of the erase, read and write margins for EPROM chips in the software settings?
If your programmer lets you set or specify voltages for erase, read, and write, you can check margins as you choose (or don't choose). If there are no options, you have to depend on the design quality of your programmer.
 

dl324

Joined Mar 30, 2015
9,331
Most technicians I have worked with don't know either it seems.
I was a technician once and I can say from experience that I've worked with a lot of technicians who didn't know what they were doing most of the time. I learned about EPROMs at a company I worked for (35 years ago). It wasn't my job to design them, but I learned about them because I was interested.
 

dl324

Joined Mar 30, 2015
9,331
He means you are getting nowhere.
dl324, here is the situation, SamEricson fits the profile of someone who has been banned from this forum and several other forums several times. He keeps coming back under a different name. He asks the same questions over and over again in different ways and never resolves the problem. He eventually causes arguments among the forum members. This is why he is banned.
Thanks for the tip. I haven't been on this website long enough to learn about games people play.
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
Thanks dl324 for your information and time

I think my whole problem is the types of universal programmers I have used in the past and current. They just don't have the functionality or options to do the erase, read, write and check sum correctly.

I'm going to re-read my universal programmer manuals again to see what I am missing or overlooked.

You do seem to know about about programming EPROM and EEPROM chips which it's hard to find people these days that know how to work these universal programmers right. Most techs i worked with don't know about them much or how to set them up.

At one of my jobs the techs were using the UV timer set to 50mins when erasing the ERPOM chips which was killings the cells. They thought the more UV erase time the better it will get erased. They all had college degrees in EE or at ITT tech.
 

dl324

Joined Mar 30, 2015
9,331
Thanks dl324 for your information and time
My working career is over and I'm glad to help others if I can.
You do seem to know about about programming EPROM and EEPROM chips which it's hard to find people these days that know how to work these universal programmers right. Most techs i worked with don't know about them much or how to set them up.
Part of my hobby is building/modifying EPROM/EEPROM/FLASH programmers. I use these devices in some of my projects and it's important for me to understand the technical details.
At one of my jobs the techs were using the UV timer set to 50mins when erasing the ERPOM chips which was killings the cells. They thought the more UV erase time the better it will get erased.
There are many things in life where more isn't better. Program/erase cycles for EPROMs are measured in the dozens. If you erase for 2-3X longer than necessary, you're going to affect device lifetime.
They all had college degrees in EE or at ITT tech.
As with most things, not all degrees, or people for that matter, are equal. When I was a tech, one of my fellow techs had a BSEE from UC Berkley. Most people with a BSEE would be working as an engineer, not a tech; and he wasn't even a very good tech. When I left one of my technician jobs, my replacement had a MSEE from Stanford; go figure...
 

Thread Starter

SamEricson

Joined Apr 25, 2015
196
building/modifying EPROM/EEPROM/FLASH programmers.
Can I ask what kind of modifications you do to EPROM and EEPROM programmers?

I never knew you could modify one or what kinds of modifications to do to them
 

Brevor

Joined Apr 9, 2011
297
I never said I did, that is why i'm trying to learn the correct way of erasing, reading, writing, checksum . etc. about EEPROM chips and ERPOM chips.
It should all be in the user manual of the programmer you are using.
 

dl324

Joined Mar 30, 2015
9,331
Can I ask what kind of modifications you do to EPROM and EEPROM programmers?
I was a moderator on willem.org before Willem passed away. Willem programmers were a collaboration among many people and there are literally dozens of variants. I made it a point to understand the strengths and weaknesses of any design I helped people with. Many of them had problems in how voltages were generated, so I would offer suggestions on how their owners could improve them. Some were just bad designs, but that didn't stop them from being sold. The software started out open, but was later converted to a closed design. I helped people work around limitations in the software.
I never knew you could modify one or what kinds of modifications to do to them
With all commercial programmers I worked with, they were closed designs and manufacturers would reveal little information. When I contacted Stag about the problem I discovered in one of their designs, they simply told me it was obsolete and I should buy a newer one. That was the last time I used a commercial programmer...
 
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