Hi Lawrence,

> What happens to the OSCCAL number when you UV erase a windowed

Get erased.

> PIC12C508?  Is the OSCCAL even programmed into windowed parts in the
> first place?     I've noticed that piezo beepers hooked up to two

Yes.

> different windowed parts usually have different tones, meaning the
> oscillators must run at different freq's.

Trimmed frequency is still out by 1.2 % max and untrimmed by 10%

Beating could be heard in trimmed devices, absolute difference
on two untrimmed devices if you have a good ear.

Check out my link below that describes very simple program
to recover a lost OSCCAL value from a 12C50x/JW device.

If you are not fussy select 7 as the OSCcal value.  The median is
there so you will minimise bulk error.

   http://www.ip.co.za/people/kalle/pic/default.htm#caltest

Cheers
--
Kalle Pihlajasaari   kalle@ip.co.za   http://www.ip.co.za/ip
Interface Products   P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750   Fax: 402-7751    http://www.ip.co.za/people/kalle

DonTronics, Silicon Studio and Wirz Electronics uP Product Dealer