Hi Elia,

my question again:
Why to the hell anybody think, that [s]he need always the biggest RAM / ROM ???
Especially also before any line of code was written.


Whats the reason, why most derivates have only 4kB ROM internal ?
Right, its based on the practical experience, that most applications fits already in 4kB.
Also internal XRAM seldom exceed 1kB.


But if you really sure, use a PALCE20V8 or similar to reserve 256 bytes from the RAM and use it as I/O.
On outputs its not needed to disable the RAM, only on reading inputs.
Then on outputs the RAM can be used as shadow register to read back.


Peter