MCUmall EPROM BIOS Chip Burner Forum
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 PLCC 27c256 can not write and erase
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edden

USA
3 Posts

Posted - 07/25/2007 :  05:19:32  Show Profile  Reply with Quote
Hi My Willem universal programmer word great on read the 27C256 (PLCC)but can not erase or write.I did try select different voltage and defferent set up but still not work.Please help.
Reply #1

ZLM

2937 Posts

Posted - 07/25/2007 :  13:13:42  Show Profile  Reply with Quote
The PLCC32 type 27C256 is OTP (One Time Programmable) chip. So, there is no way to erase it.
Unless there is a glass window on it, then you can use UV light eraser to erase it.
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Reply #2

DL

USA
46 Posts

Posted - 07/25/2007 :  17:54:06  Show Profile  Reply with Quote
Hi,

Are you using a PLCC32 to DIP28 adapter/socket? If not, the device won't be read correctly and the program won't give an error...

HTH,
Dennis
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Reply #3

edden

USA
3 Posts

Posted - 07/26/2007 :  10:52:19  Show Profile  Reply with Quote
Thank you DLM and Thank Dennis.I try to erase the AT27C256R Dip 32 socket,read ok but can not erase or write,this chip does not have the window for UV light.
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Reply #4

DL

USA
46 Posts

Posted - 08/02/2007 :  11:34:35  Show Profile  Reply with Quote
EPROMs in packages without quartz windows can't be erased. They can be reprogrammed as long an no bits need to be erased.

The electrically erasable EPROMs (e.g. 27SF512) are actually FLASH devices marketed as EPROMs.

HTH,
Dennis
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Reply #5

jdmbubble

2 Posts

Posted - 10/08/2007 :  14:28:41  Show Profile  Reply with Quote
So how exactly would someone go about reprograming a 27c256 or is it easier just to buy a 27sf512
thanks for the feedback
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