Hi Nikos

A word is indeed 16bits, there is a great post by Melanie in the FAQ section I think, which describes how to address bits bytes words and arrays,

but I think first it is worth taking the time to fully digest pages 21 to 24 of the PBP manual. Every minute taken will pay back in Spades. Settle back with a nice cool glass of retsina.... take your time.

Just in case you do search for other info: a nybble is 4 bits but PBP does not access these directly.

Cheers and good luck

Duncan