(Topic ID: 260925)

Eproms and Burners

By oldschoolbob

2 years ago


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  • 75 posts
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  • Latest reply 5 days ago by harig
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    There are 75 posts in this topic. You are on page 2 of 2.
    #51 2 years ago
    Quoted from barakandl:

    Use the file size of the image to decide what ROM to use. In windows it shows bytes so mutiply by eight. If your file is 128KB in windows explorer would go fit on a 1Mbit 27C010 but you could also use any of the other 32pin JEDEC standard pin out EPROMs as a replacement IE 27C040. Just fill up the EPROM with repeated copies of data until full.

    Here is a chart on wikipedia that will help pick an EPROM based on the file size.
    https://en.wikipedia.org/wiki/EPROM#EPROM_generations,_sizes_and_types

    Got it, and that Wikipedia chart looks super useful. I will pay attention to the image file size, and pick an EPROM that can handle that size, or larger with the same pin count package.

    Using this info has now helped me identify why I'm having trouble figuring out in advance how to burn a U7 Bootflash EPROM to update the Sound OS on my LOTR before installing the LOTR LE 10.02 CPU code in preparation for adding a shaker. The file image I was intending to use to burn the U7 Bootflash EPROM is named BIOSv8.u8 and is 128KB in size. I got that file per this Pinside reference: https://pinside.com/pinball/forum/topic/how-to-install-shaker-motor-in-lotr-standard-edition/page/5#post-3080604. That must not be the correct file because a 128KB file would require a 1Mbit chip or larger, but a 1MB chip is not the correct pin count package (too big) to fit into the 28 pin socket at U7. So, I will start the search again for the correct image file for the U7 Bootflash EPROM, and when I find that then I can burn it to a 28 pin EPROM of the appropriate size (or larger including repeat copies to bulk up the file image).

    Unless this is indeed the correct file, and there is a different reason why it shows at 128KB on my computer's hard drive?

    #52 2 years ago

    How do the Checksums work for EPROMs? I just noticed that the checksum calculated by the GQ-4x4 for a given image file changes based on what Device you select. It varies for size of EPROM, and even more interesting for the same size EPROM the checksum differs between different EPROM manufacturers. For a particular file I have, when I select AMD AM27512 the GQ-4X4 software displays a checksum value of 00A68ED5, but when I select ST M27512 the GQ-4X4 software displays a checksum value 00FC9040. Why is that?

    Hmm, it may be because I was erroneously looking at a file too large to fit on the target EPROM. Using another file, 64KB in size, I get exactly the same calculated checksum values when selecting either the AMD AM27512 EPROM as the Device, or the ST M27512 as the Device, which seems normal.

    #53 2 years ago
    Quoted from RoyF:

    How do the Checksums work for EPROMs?

    The checksum is usually the sum of all bytes you're programming.

    If you're burning the same file to two EPROMs of the same size/bit orientation, the checksum will be the same.
    So in your case the same file should show exactly the same checksum when burning an AMD AM27512 or a ST M27512 since these EPROMs are the same capacity and are equivalent.

    #54 2 years ago
    Quoted from Quench:

    If you're burning the same file to two EPROMs of the same size/bit orientation, the checksum will be the same.

    That is good to know. I wish I had taken screen shots to show what I observed before. But looking again now using the same file as before I am indeed getting identical checksums from compatible EPROMS by different manufacturers. Not sure why I didn't see this when checking earlier, but I will chalk it up to "user error" of some kind. Thanks Quench!

    #55 2 years ago
    Quoted from RoyF:

    How do the Checksums work for EPROMs? I just noticed that the checksum calculated by the GQ-4x4 for a given image file changes based on what Device you select. It varies for size of EPROM, and even more interesting for the same size EPROM the checksum differs between different EPROM manufacturers. For a particular file I have, when I select AMD AM27512 the GQ-4X4 software displays a checksum value of 00A68ED5, but when I select ST M27512 the GQ-4X4 software displays a checksum value 00FC9040. Why is that?
    Hmm, it may be because I was erroneously looking at a file too large to fit on the target EPROM. Using another file, 64KB in size, I get exactly the same calculated checksum values when selecting either the AMD AM27512 EPROM as the Device, or the ST M27512 as the Device, which seems normal.

    After you change chip profile in GQ-4X reopen the image file.

    If you open a 4k image while a 2k chip is selected and then select a 4k chip the software will truncate the last half of the image. So you must reopen the file again. I hope that makes sense.

    #56 2 years ago
    Quoted from barakandl:

    If you open a 4k image while a 2k chip is selected and then select a 4k chip the software will truncate the last half of the image. So you must reopen the file again. I hope that makes sense.

    That does make sense, and I did see the truncate message. I'll make it a habit to select the Device (chip) first, and then load the file.

    2 years later
    #57 7 days ago

    Looking to do some ROM programming and going to pickup the GQ 4x4. I'm looking at EPROMs for Williams System 11 machines; they take the 27256 and 27128 chips. Looking on eBay there is different brands and models; mainly ST Micro and AMD seems to be the two major brands for this type. As long as it is 27256 or 27128, does the rest of the model number really matter? I'm seeing subtle differences in parts numbers past that point. Just want to make sure before I purchase. Thanks.

    #58 7 days ago

    They could be different in terms of programming voltage etc. but for the most part you are ok. There is an eeprom version of the 256 that does not work IIRC.

    What I do now is just buy winbond 27512 ee version and double/quadruple up the images.... way more convenient than using the UV lamp to erase. But I go through tons of burns so the burn-erase cycle is a PITA.

    You could just get 256's and double them up as well, general rule is the older the eprom, the more variation in voltages, etc. with older ones being more stubborn.

    #59 7 days ago
    Quoted from slochar:

    They could be different in terms of programming voltage etc. but for the most part you are ok. There is an eeprom version of the 256 that does not work IIRC.
    What I do now is just buy winbond 27512 ee version and double/quadruple up the images.... way more convenient than using the UV lamp to erase. But I go through tons of burns so the burn-erase cycle is a PITA.
    You could just get 256's and double them up as well, general rule is the older the eprom, the more variation in voltages, etc. with older ones being more stubborn.

    Gotcha. So how does getting the 512’s and doubling or quadrupling save you from having to erase?

    Do you see any issue with getting these?

    ebay.com link: itm

    ebay.com link: itm

    #60 7 days ago

    The 256's aren't too badly priced. The 128's are overpriced.

    The winbond 512's are electrically eraseable - the burner tells it 'erase first', then burn. It's more like an nvram that way. So no need to slap them in the UV eraser for 20-30 minutes after using (I write/test others software for these games so I need to erase/burn a lot of eproms).

    I'll develop/test with the 512's, then when it's 'finalized', I'll burn to a 128/256 setup. I got 200 256's from a music instrument refurbisher a couple years ago, they were cheap, 200 for $110 or so. I had to scrape off a difficult to remove yamaha 'genuine' label on each of them and soak them in alcohol to get the glue residue off. My finger still twitch thinking of that.

    #61 7 days ago
    Quoted from slochar:

    The 256's aren't too badly priced. The 128's are overpriced.
    The winbond 512's are electrically eraseable - the burner tells it 'erase first', then burn. It's more like an nvram that way. So no need to slap them in the UV eraser for 20-30 minutes after using (I write/test others software for these games so I need to erase/burn a lot of eproms).
    I'll develop/test with the 512's, then when it's 'finalized', I'll burn to a 128/256 setup. I got 200 256's from a music instrument refurbisher a couple years ago, they were cheap, 200 for $110 or so. I had to scrape off a difficult to remove yamaha 'genuine' label on each of them and soak them in alcohol to get the glue residue off. My finger still twitch thinking of that.

    Ok, so no issues with using an EEPROM whereas the originals were EPROM? I am going to be doing some software beta testing, so that may be very handy.

    #62 7 days ago
    Quoted from slochar:

    There is an eeprom version of the 256 that does not work IIRC.

    You might be thinking of the AT28C256 which has a slightly different pinout to 27256

    SST27SF256 are a EEPROM version that looks pin compatible. Cheap out of China.

    #63 7 days ago
    Quoted from interconnect:

    Ok, so no issues with using an EEPROM whereas the originals were EPROM? I am going to be doing some software beta testing, so that may be very handy.

    True.
    Back in the day, I had a ROM-IT. The device was basically a computer controlled ram.
    You downloaded the .bin file of the game to it and it plugged into the ROM socket.

    #64 7 days ago

    So I should be Ok if I get the ones I linked above? In terms of that it’ll work in the machines (Bad Cats, Pin Bot). I checked the programmers list of supported chips and they are in there minus the last few digits.

    #65 7 days ago

    Get the largest size EEPROM in the pin count package. It feels like a waste of money to stock 2764, 27128, 27256 and 27512 when a W27C512 can replace all of those and is probably the cheapest. There might be some rare cases where you need to pad the data in a certain way to use a 27C512 as a 27256 (supposedly some R-Dog sys 11, but not sure as the stock boards work fine with larger mem), but normally you can fill up the chip with repeated copies.

    SST27SF256

    has good endurance, 1000 cycles 100 years. But ive seen some flash memory I end up not buying because they are only guaranteed to hold memory for ten years after a burn, which is probably a conservative estimate, but worth looking at the datasheet and considering.

    #66 6 days ago
    Quoted from barakandl:

    But ive seen some flash memory I end up not buying because they are only guaranteed to hold memory for ten years after a burn

    Data retention spec for early EPROMs like 2716 was 10 years too - the spec was usually at maximum ratings.
    I haven't seen many of these 40 year old games with EPROMs suffering bit rot though.

    The concern these days is the current crop of cheap programmers not burning cells with enough margin that will result in reduced data retention (data loss in years rather than decades).

    The below article is taken from "Intels 1984 Memory Components Handbook" and discusses the move to intelligent/fast EPROM programming and dealing with verifying cells at different voltages to ensure good margins. May be an interesting read for some.

    EPROM_Intel_Versatile_Algorithm_Equipment_Cut_EPROM_Programming_Time.pdf
    #67 6 days ago

    I think I have never seen a pinball EPROM suffering from bit rot even though some are 40 years old. But some that I did burn myself with a home made programmer in 1980's, do suffer from occasional bit flips. Maybe that tells more from my programmer than the chips

    This is probably my first EPROM project from 1985. A terminal from Intel data book application note, for my first homemade micro. The 2716 EPROM's are still OK!

    term (resized).jpg

    #68 6 days ago
    Quoted from Tuukka:

    I think I have never seen a pinball EPROM suffering from bit rot even though some are 40 years old.

    It happened with my Black Hole. I turned it on after a few months of no use and was suddenly getting the 7641 ROM error on the displays. The factory game 2716 EPROM had some bad bits. This was probably about ten years ago.

    Quoted from Tuukka:

    This is probably my first EPROM project from 1985. A terminal from Intel data book application note, for my first homemade micro. The 2716 EPROM's are still OK!

    Impressive!

    #69 6 days ago

    Might be the Black Hole was using EPROM's a bit earlier than Williams games. I think the first EPROMs I saw were in Sys 6 games, before that they used mask ROMs. Anyway, the BH EPROMs might have been quite early production 2716's so no wonder that with a "versatile algorithm" they might fail only after 40 years

    As for my impressive terminal board... cover your eyes and be very careful looking at this rats nest at the back side... Prototyping boards were expensive then.

    20221125_183517 (resized).jpg
    #70 6 days ago
    Quoted from Tuukka:

    Anyway, the BH EPROMs might have been quite early production 2716's so no wonder that with a "versatile algorithm" they might fail only after 40 years

    I still have that chip, it was a Hitachi 2716. No date code but must be '79 or '80.

    Quoted from Tuukka:

    As for my impressive terminal board... cover your eyes and be very careful looking at this rats nest at the back side... Prototyping boards were expensive then.

    That is a work of art!

    #71 6 days ago
    Quoted from Quench:

    I haven't seen many of these 40 year old games with EPROMs suffering bit rot

    My side note:
    I finally have a Williams/Bally DCS sound board EPROMs fail.
    The game would boot and give one bong...
    Through the years the "bong" would finally give six bongs to one bong... Finally stayed on six bongs.
    I had to replace two EPROMs; all back to just one power up bong.
    This is my first experience, with a personal game, that the EPROMs have failed.
    Odd and fascinating at the same time.. I'm so glad pinball enthusiast people have made copies of the
    SND software, I owe them a bit of gratitude.

    #72 6 days ago

    Had the same thing on Pinbot sound ROM... Booted fine and worked for a couple minutes. Verified fine. Reburnt fine. Always same symptoms. Finally just tried another EPROM.... Bang, working great since then.

    Probably just its time or heat related.

    #73 6 days ago
    Quoted from vec-tor:

    My side note:
    I finally have a Williams/Bally DCS sound board EPROMs fail.
    The game would boot and give one bong...
    Through the years the "bong" would finally give six bongs to one bong... Finally stayed on six bongs.
    I had to replace two EPROMs; all back to just one power up bong.
    This is my first experience, with a personal game, that the EPROMs have failed.
    Odd and fascinating at the same time.. I'm so glad pinball enthusiast people have made copies of the
    SND software, I owe them a bit of gratitude.

    I just replaced a High Speed sound EPROM, failed checksum.

    #74 5 days ago

    When i fixed original boards the PROMs on William's speech boards very often had bit rot. There would just a few a words garbled. Read back the chip and it was mostly good. Those are masked ROMs though if it matters. I can't really remember any other bit rot like issues on old EPROMs that where not a total failure of the EPROM and usually caused by over voltage or plugging the chip in "upside down".

    I got back a GTB System 3 MPU where the six pin power connectors for the power board got swapped. Every EPROM in the game but the GPROM was damaged to a point it was totally dead. The MPU GPROM did not verify right but was close, I was able to erase and reburn it and it seemed fine.

    My BSD occasionally gets a credit dot for ROM checksum error at power on. It always plays fine, I've ignored it for a couple years now.

    #75 5 days ago

    My Sega Frankenstein had a few speach samples garbled but did not report any faults.
    Cleaning pins and reseating did not help
    Replaced the Rom and worked fine

    There are 75 posts in this topic. You are on page 2 of 2.

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