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'CODE PROTECT BIT 12c508'
1997\03\17@095947 by Rob Bruce-Brand

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Sorry if this is a tired, hackneyed question....

I've two windowed 12C508's with the code protection bit set. Are they
destined for the scrap heap or not? I erased them overnight, and was
able to program them, but when I placed them in a circuit in which
the OTP version works fine, I have no joy.

Thanks
Rob

1997\03\17@104437 by Andy Kunz

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>I've two windowed 12C508's with the code protection bit set. Are they
>destined for the scrap heap or not? I erased them overnight, and was
>able to program them, but when I placed them in a circuit in which
>the OTP version works fine, I have no joy.

Try covering the window.  The chips are very sensitive to light.

FWIW, this is a very useful time to have those old black write-protect tabs
from the ancient floppy media.

Andy

==================================================================
Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865
         Hardware & Software for Industry & R/C Hobbies
       "Go fast, turn right, and keep the wet side down!"
==================================================================

1997\03\17@185944 by mike

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In message  <97Mar17.165816gmt+spam_OUT0200.41224-1TakeThisOuTspamcity.durban.gov.za>
.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU writes:
> Sorry if this is a tired, hackneyed question....
>
> I've two windowed 12C508's with the code protection bit set. Are they
> destined for the scrap heap or not? I erased them overnight, and was
> able to program them, but when I placed them in a circuit in which
> the OTP version works fine, I have no joy.
>
Rob,

The 12C508JWs can be code protected and un-code protected at will,
so the problems must lie somewhere else. Have you covered the window?

Regards,


Mike Watson

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