It was corruption in the PICSTART Plus firmware, apparently.  After 
replacing the PICSTART Plus CPU with one that had the latest firmware (3.11) 
in it, the problem went away.  The previous version was 3.10 and should have 
supported the '540 equally well.

"mc" <mc@delete.this.uga.edu> wrote in message 
news:41d49e0a$1@mustang.speedfactory.net...
>I recently found, amid my stock of components, five UV-erasable 
>PIC16HV540s. These are the PIC with the built-in voltage regulator that can 
>operate from a 12-volt supply.
>
> My PICSTART Plus said at first that they weren't blank; the first 45 or so 
> memory locations would read back as 0 rather than FF.  On subsequent 
> tries, the region of 0's grew, and now it says they're code-protected.
>
> I've tried UV-erasing them, and this had no effect, or made the problem 
> worse.
>
> Is this by any chance a known problem with PICSTART Plus (firmware 3.10 
> with MPLAB 7)?  Or a known problem with the PIC16HV540?
>
> More generally: What micros are on the market other than this one with 
> built-in voltage regulators?
>
> Thanks!
>
> 

I recently found, amid my stock of components, five UV-erasable PIC16HV540s. 
These are the PIC with the built-in voltage regulator that can operate from 
a 12-volt supply.

My PICSTART Plus said at first that they weren't blank; the first 45 or so 
memory locations would read back as 0 rather than FF.  On subsequent tries, 
the region of 0's grew, and now it says they're code-protected.

I've tried UV-erasing them, and this had no effect, or made the problem 
worse.

Is this by any chance a known problem with PICSTART Plus (firmware 3.10 with 
MPLAB 7)?  Or a known problem with the PIC16HV540?

More generally: What micros are on the market other than this one with 
built-in voltage regulators?

Thanks!