program memory

[ivanperino]

Hello.

I wonder if it would be possible to use external flash as a program memory on PIC16F88. I know this sound a little stupid but there are some chips that write them selves, although 16F88 has not this capability, thinking on using external memory as program memory would be a fantastic solution.

Thank you and I am sorry if am VERY wrong.

[Ttelmah]

Not properly on the F88.
There are two ways of doing this. The first is not to use the external memory as 'program memory', but use it as numeric storage, holding a sequence of instruction 'keys', which select whch routines to run in the main memory. This is the approach used in things like the Stamp units, with the main chip holding the iterpreter code, and the external memory the code to be interpreted. This can be done on any PIC.
The second is to really 'run' the external code. This requires a chip that allows the external memory to be mapped into the main program address space. It also requires quite a few pins, to provide high speed addressing of the external memory. Look for chips that offer 'extended' microcontroller modes. Typical example, would be the 18F8720.

Best Wishes