Electronics > Projects, Designs, and Technical Stuff
Game ROm..damaged ? 27C040
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powerchisper:
Hello friends:

You may have read in the other posts that I'm in a pinball repair.
As I suspect the game ROM could be damaged, I took it to my friend to see if he could read it with his Willem programmer.
He read the chip, but we dont't know how to interpret the results. It came as a "hex" file ( that is what we think it is ).
There are lots and lots of numbers and letters arranged by offset, etc, but we see lots and lots of "BF" and "FF", large blocks in between.

Maybe someone can give me a hint ? May this be corrupt parts of the ROM or is it normal ?

I downloaded a supposedly working file from the net and it ¡s similar, but we get all FF instead of BF.

Thanks in advance and greetings from Spain.
dmills:
Unused space in eproms defaults to FF (1111 1111 binary), BF would be 1011 1111 so it may be your ROM has bit 6 failed. Slightly odd, age related bit rot generally turns a zero into a one.

Grab a new chip, burn that eprom image you got of the net and see if it works?

Regards, Dan.

powerchisper:
Thank you so much !! I'll tell my friend to erase it and record the downloaded code ( fingers crossed that the chip is not physically damaged ).
I have noticed that the little window on top of the IC has a 1mm exposed area, as the sticker that covers it is not very well aligned....coluld that be a serious problem ?
The board also had battery leakage, and seems that it has been stored for years in a wet environment.

The reason I suspected it could be bad is because the 5V Led on the board was fried.
NivagSwerdna:
Firstly check you have the right image to burn into the chip!

Then UV Erase to all FFs and then burn again.

Old ROMs do lose their values and should be erased and re-programmed.  I currently have some I need to sort out that read different values at some locations on subsequent reads... really needs to be reprogrammed.
Completely cover the quartz window will something opaque after erasing.

Keep a copy of the image in a safe place.

(Of course if you have damaged the chip... you will need to buy a replacement)
digsys:
Those EPROMS were pretty tough. Even with no window protection, you'd need a LOT of background UV to scramble it. The amount would fry your body first :-)
I kinda doubt it is "faulty". Big blocks of BFh are TOO precise, NOT what I'd expect from background UV damage. It was "possibly" a default table / data area
preset, or the nerd who wrote it got lazy :-)
EVEN IF the BFss were supposed to be FFhs, it is an ERASED or UNUSED part of the memory map anyway, so who cares.
Give it a go and report back.
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