Keithley 1923 GPIB-card

[wiss]

My Keithley 192 seems to suffer from a bit-rot problem, when the GPIB-card is plugged in it will mostly just flash the front LEDs, when I unplug the GPIB-card it seems to work properly. I did check the 5 V supply, about 4.9 V and no ripple.

The EPROM on the GPIB-card is a "HN462716G", is that one compatible with any obtainable EPROM?
What would be a good reader/writer for these EPROMs?
At home I only run Linux but I could borrow a windows-machine at work in case of emergency....

[PA0PBZ]

HN462716G sounds like a 2716 derivate, you could probably use any of those, if there are any differences it will most likely be in the programming and not in normal use.
For the programmer... almost any will do, if you don't have one have a look at the TL866.
But... what makes you think there is an error with the eprom? And if there is a faillure in the original one it will not do you much good reading that one and program the failed contents into a new one. It could easily be a problem with the TTL buffers on the pcb.

[wiss]

Well, EPROMs are only guaranteed to hold their data for 10 years? I've heard...
My old ZX-spectrum started to develop weird behaviours at that age, which I at the time blamed on the EPROM.
This EPROM would be close to 30 years old now.

Occasionally it will power up and run for hours with the GPIB-card plugged in, if I read the EPROM several times I might get the correct data a few times?

If that fails I'll ask here if someone can dump it for me

[wiss]

So, got my tl866a today 
Used the linux CLI-tool to read it out a few times and did a hash of each read, they seems to be identical, good, no problem with that eprom, right?

eelwing: 18:27 /home/Scratch/wiss/minipro% foreach i (gpib-rom-* )
foreach? sha1sum $i
foreach? end
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-11.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-12.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-13.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-14.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-15.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-16.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-17.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-18.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-19.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-21.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-22.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-23.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-24.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-25.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-26.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-27.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-28.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-29.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-31.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-32.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-33.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-34.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-35.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-36.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-37.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-38.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-39.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-41.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-42.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-43.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-44.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-45.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-46.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-47.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-48.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-49.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-51.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-52.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-53.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-54.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-55.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-56.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-57.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-58.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-59.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-61.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-62.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-63.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-64.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-65.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-66.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-67.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-68.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-69.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-71.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-72.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-73.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-74.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-75.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-76.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-77.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-78.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-79.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-81.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-82.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-83.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-84.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-85.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-86.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-87.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-88.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-89.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-91.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-92.hex
908683e0317745f7f45ab7e38c67cdf4dfbc10ba  gpib-rom-93.hex

[merox]

Used the linux CLI-tool to read it out a few times and did a hash of each read, they seems to be identical, good, no problem with that eprom, right?

Usually the trick is to read the EPROM a few times with different supply voltages to check if some bits flip when the voltage changes (although i'm not sure which supply voltage range to check). Have you done that or have you used 5 volts all the time?

[wiss]

Used the linux CLI-tool to read it out a few times and did a hash of each read, they seems to be identical, good, no problem with that eprom, right?

Usually the trick is to read the EPROM a few times with different supply voltages to check if some bits flip when the voltage changes (although i'm not sure which supply voltage range to check). Have you done that or have you used 5 volts all the time?

Can I change that?
Right now I'm using the command-line tool...

[wiss]

Got the win-software running in wine, the last 16 bytes of the gpib-eprom reads the same down to 3.3 V, another erased chip red FF on 4 V and 00 on 3.3.

[merox]

Can I change that?
Right now I'm using the command-line tool...

I don't know how to change that, but it must be possible somehow.

But today I coincidentally stumbled upon an explanation about what happens to the contents of the EPROM when it ages, unfortunately it's german - it can be found here: http://robotrontechnik.de/html/forum/thwb/showtopic.php?threadid=11457#107449 .

A brief explanation in english would be: All the information inside the EPROM is basically stored in tiny capacitors which are either charged or not, making a bit appear as one or zero. Since there is always some kind of leakage involved, the capacitors discharge over time - the information gets lost.

By lowering the supply voltage of the chip you're trying to read out, you shift the switching thresholds of the circuitry inside the chip slightly. This shift is then hopefully enough to flip the 'broken' bits back to the original value, at least long enough to read the contents of the chip.

But there is no guarantee that this technique works.

Got the win-software running in wine, the last 16 bytes of the gpib-eprom reads the same down to 3.3 V, another erased chip red FF on 4 V and 00 on 3.3.

I guess you should better read the whole chip and not only a few bytes since you don't know at which address a bit might have been flipped. But to be honest i've no experience with that, i'm just more or less citing what i've read before.

[wiss]

Sometimes the 192 works with the 1923 in, it always work with the 1923 out, I don't think it's a problem with the eprom contents anymore.

[wiss]

By lowering the supply voltage of the chip you're trying to read out, you shift the switching thresholds of the circuitry inside the chip slightly. This shift is then hopefully enough to flip the 'broken' bits back to the original value, at least long enough to read the contents of the chip.

If the eprom memory cell is a floating gate mosfet with source to gnd this makes sense! (is it?)

[wiss]

The k192 seems to work now, I tried to read the EPROM at lower voltages, got the same checksum for all but 3.3 V where the data was mostly garbage. The fix might have been to pull out and insert the EPROM a few times...