AndrŽ Malafaya Baptista wrote:

> Does anyone know of a version of the PIC16C84 which is an OTP
> (One-Time Programmable) device? What's its reference/name?

  The PIC16F84 uses EEPROM, so it is by definition, re-writable.  The
term "OTP" has no meaning in this respect.

  If you look at the datasheets, you will see 16CR84 devices listed
which are (cheaper!) mask-programmed versions for *high*-volume
production.
-- 
  Cheers,
        Paul B.