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EPROM code fryup?


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Hi Guys,

 

I pulled all the eproms off the cpu board of a Spy Hunter I've been working on. I compared each eprom to the images I got from edge emulation. There's only one download in the "S" directory so figured that had to be it.

 

The zip file seams to contain the right binaries. Date 11/8 on 3A through to 6A checks out. And date 2/9/84 on 7D through to 11D is also correct. I did a compare with my eprom burner and the code passes on just one eprom 11D!!!

 

It's strange to find that many corrupted eproms IMHO.

 

What's even stranger is the code I pulled of the eproms looks nothing like the code I downloaded from the edge site... has a lot of blanks, 0's, 8's,etc.. low numbers.

 

fried.jpg

 

Whereas the code I downloaded from edge emulation is full of characters you'd normally see in code @#%^ etc...

 

actual.jpg

 

Hit by lightning do you think???:blink:

 

Mitsubishi M5L2764

Edited by taito
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Well I uploaded half a dozen to romident and it identified the good one as...

 

 

Spy Hunter

(Spain,Recreativos Franco S.A.spyhuntpr PCB)

 

 

It drew blanks, gave no info on the others... :(

 

So guess I have my answer. They're Kaput!

 

I think the video proms are OK though, as I don't believe they are eproms anyway.

You can see bits of graphics in this pic. Spanish graphics maybe? :)

 

sh.jpg

 

I'm thinking a fresh batch of EPROMs would be the best option.

 

What's people experience here? Are EPROMs that have severely lost there code reusable?

Edited by taito
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The sticker are in tact and the board is sandwiched in between two other boards.

 

But thanks and cheers for asking. It's a weird one, don't quite understand.... :huh:

 

It will be interesting when I get my uv eraser, I can erase them and try and see if they hold code.

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If they are the Mitsubishi type with the raised square platform around the window then I'm not surprised. I've met quite a few boards with those ICs and they do seem to die of old age. You'll probably find only a few can be fully erased, and only half of those can programmed successfully, and of those almost all will verify as bad less than an hour later after the bit-rot sets in again.

 

Mitsubishi seem to have changed design midway through the 27c128 era, so you find a mix of raised-square topped 128s and flat surface ones, and the ones without the square platform don't seem to have this issue. The 2764s seem to be worst hit as they were almost all square topped.

Edited by Womble
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Thanks @Womble,

 

they are indeed the raised square type from Mitsubishi.

 

So it sounds like they're pretty much garbage.

 

It's good to get to the bottom of it. Cheers!! :)

 

 

Here they are waiting for the sun to come out.. but now they've been told they wont be allowed out to play... :(

 

naughty eprom.jpg

Edited by taito
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