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EPROM reader

D

DimensionDude

Experienced Member
Joined
Jun 4, 2005
Messages
363
Location
Arkansas, USA
I've built an eprom reader as shown here http://www.zws.com/products/epromr1/index.html and I'm not sure if it's working right or not.

The main thing is that the software doesn't support the 2732 eprom that the Dimension 68000 uses. If I use the supported modes, I get the same results from every read for that particular mode, i.e. if I use the 27128 mode I'll get the same file for each read of the same chip.

The main thing is that the author doesn't include the source code for this particular project. He does, however, include the source code for the reader/burner project but it doesn't support the 2732, either. Anyway, looking at C source code doesn't tell me anything since I don't know C.

It may be a coincidence, but the first computer that I connected it to died, never to boot again. Thinking that having it grounded through the parallel port was not a good thing, I connected a different ground and hooked it up to a different computer (the dreaded M919). So that's where it stands now, I'm getting some sort of result, I just don't know if it's the right result.

I may be able to kludge something up in BASIC, but it will probably take awhile.

Kent
 

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Hmm...replying to myself. An early sign of senility?

Anyway, I've bodged together a BASIC routine that operates the address counter perfectly. This has been tested by removing the rom and connecting the address lines (well, 8 of them) to the data lines. With those 8 lines I get a perfect count of 0-255 every time.

Here's where it goes wrong. With the rom in place it sometimes misses a byte. Just one, and always in the same place on that rom. Other roms exhibit the same behavior but it's not the same byte that's missing. I've fiddled with the timing and tried decoupling capacitors on the Vcc, no help.

At present, the program only puts the data on the screen and I usually retrieve 100 bytes so that at least a couple of runs can be viewed at once (makes it easier to see any discrepancies).

I'm not 100% convinced that it's timing or spurious signals since the "error" always occurs at the same address.

Anyone have any ideas?

Kent
 
Well, after more troubleshooting it appears that the problem is poor connections on the breadboard. If I wiggle the wires around a bit (very technical, only a trained professional should attempt) then the reads are consistent for a few minutes then start getting screwy again.

Buy one? BUY one?!? :)

Believe me, if I could afford a burner I would have one.

Kent
 
Kent...I'll take a look at this when time allows. I'm no expert at C or electronics, but I know a little of both. Looking for a house right now...maybe later this week. I'm interested in burning my own proms too. Later.
 
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