" MICROCHIP ACKNOWLEDGES PROBLEM -- The chip fabrication process for the
PIC12C508 and 12C509 underwent a change earlier this year. This has resulted
in a problem for PIC users working time-critical applications on the
internal-oscillator of the part. To be brief: the 4-wire version of the
modchip made on PIC12C508/9 parts is not guaranteed to work on PICs with a
date code of 9813 through 9830 (12C508), 9820 through 9830 (12C509). All
factory codes are affected. Since this is a fault in the chip fabrication
process and not the program the chip runs, the only 100% solution at this
time is to program chips in the 5-wire mode and use an external clock for
these chips."
                 from: www.aeug.org/

  I found this information by accident. I have an application on a 12c508
chip  date code 9823 and despite  the fact is not a 'time critical
application', the chip suddenly stop working without any  apparent reason
for the failure.

 Does anyone know the right source to be updated with information like this?
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      ICQ# 10909825   \_ /     \___________
      erivera@umemphis.campus.mci.net