MCUmall EPROM BIOS Chip Burner Forum
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 True USB Willem Programmer (GQ-2X,3X,4X & GQ-4x4)
 Cypress CY27C128 reading 00's not FF's when blank
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zeusthedog

Australia
1 Posts

Posted - 08/28/2014 :  20:05:33  Show Profile  Reply with Quote
Hi Guys,

I have an issue blank verifying and therefore writing to a Cypress EPROM CY27C128.

After UV erasure, the EPROM reads as all 00's, not all FF's.

I have read that this is a "normal" function of the Cypress chip, something to do with a high speed feature built into the chip design, that means when blank the chip reads as all 00's.

My question is; How do I get the GQ-4X software to verify the chip as blank when it reads all 00's and allow me to then perform a subsequent write? Or is this not possible with this programmer/software, thus it is not compatible with the CY27C128 chip series (or probably any Cypress EPROM).

I have successfully written an M27C256B (ST brand) with the programmer, so I know the programmer is OK.

As an aside, I had to rewrite the Device parameters for the M27C256B to get it to write successfully, as the default device parameters had the incorrect speed setting and write Vpp voltage.

If anyone needs the correct parameters for this chip or needs to know how to adjust them in the software, just ask and I'd be happy to help.

Thanks guys!
Reply #1

ZLM

2937 Posts

Posted - 08/28/2014 :  20:33:07  Show Profile  Reply with Quote
I do not think the blank chicp can read as 00. The chip must have problems.
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