Thanks to all those who replied.  Now it makes sense putting the
OSCCAL tuning number into the memory when the part is shipped.

But now I have two more related questions:

1) What are the chances of a program running if no CALL 04FFh /
MOVWF OSCCAL instructions are present at the beginning of the
program?  Bear in mind the said program should only flash an LED
every second(ish).

2) If I can get a program working and monitor the internal clock on
the CLKOUT pin and measure the frequency, is there some formula
for calculating the correct calibration value?  Silly me erased the
part before reading about internal oscillators.  Why can't Microchip
print the value on the bottom of the chip instead of programming it
into the memory?

Thanks again to all you helpful people.

Chris Morison
--
Research Student
Mechanical Engineering, University of Birmingham, UK
e-mail: c.n.morison@bham.ac.uk
web:    http://www.arcsite.de/hp/chrismorison/