Jim Main wrote:
>
> Can anyone tell me (authoratively) whether the 16C74A is one of the
> parts that can't be erased once code protected (UV parts).
>
> Reason I ask is that I can't seem to erase three 16C74A's after my
> programmer threw a wobbler and code protected them.
>
> I had a good look at the latest datasheets for the 16C74A and Microchip
> don't mention non-erasiblity at all - so what could be the problem??
>
> Any ideas??  Is it just playing hard-to-erase?

This thread again... :)

MChip's official position is that code-protected devices cannot be
erased.  I have done some playing around and have found that they _can_
be erased.  These are my observations:
 1. Some 74As can take many hours to erase (3 or 4).
 2. Code-protected parts tend to erase faster if they've been programmed
in the PIC-start plus as opposed to the ProMate II.

My eraser is a 10 year old Spectroline (original tubes).

--Matt