>Question for experienced 16C84 assembler programmers:
>In your experience, what is the most severe limit on a 16C84:
>- processing speed
>- stack depth
>- code size
>- data size (file registers)
>- eeprom size
>- I/O pins
>- ????
>
>I realise that no single definitive answer exists,
>but I'd like to hear some opinions.

You are right that no definitive answers exist, because a developer only chooses the PIC16C84 if the processing speed, stack depth, code size, data size, eeprom size and number of I/O pins is what he needs. If something else is needed, another hardware is used instead of PIC16C84.

On that note, this seems to be a common mistake. Some people on this mailing list first decide on a PIC, and THEN they ask whether it would be possible to do this and that with it. In a development process, one should instead first mention a product, and THEN think of the best way of designing this product so it's cheap to manufacture or whatever. Often PIC chips can be a successful solution in areas where a person without imagination wouldn't expect to see a PIC (for example in a device that needs a DTMF-sending feature), but most of the times the development time and functionality speak against using PIC chips as video cards, phone modems and anti-slipping for walking sticks.

However, I share the excitment for what microcontrollers can be used for...