Agreed - probably was a design trade off as you suggest. And it does make for easy context switching, as I said. You just have to be careful to put the page back where it was when you execute a return. I still wonder about the conversion instructions, though. Microchip DS00716A page 2 (RAM) has the sentence: "Addresses should be 12-bits long, and have the form '0x0nn' (the first 4 bits are always 0 for Bank 0" (The emphasis is mine) Makes me wonder if they were planning a flat address space and changed their minds (?). Roy ----- Original Message -----=20 From: "Jan-Erik Soderholm XA (TN/PAC)" = To: Sent: Wednesday, January 14, 2004 6:49 PM Subject: Re: [PIC]: I hope I am missing something here > Roy J. Gromlich wrote : >=20 > > Combine that with information > > which placed the "access bank" in the upper half of Page15,... >=20 > *and* the lower half of page 0, don't forget ! :-) >=20 > > and I made the jump to thinking the RAM space was flat, not > > segmented.... >=20 > Well, the MOWFF instruction (move one reg to another) takes > two 12 bit addresses directly in the instruction, so it's flat > *sometimes*. So it depends on how you look at it, right ? >=20 > > As I said, I can't understand why they fixed almost all of the > > other addressing oddities and left the Page Register in there. >=20 > Perhaps there isn't room for the (extra) bits in the instructions ? > Not without a major re-design anyway such as going to more > double-word instruction (with less speed). A design trade-of, I'm = sure... >=20 > Jan-Erik. >=20 > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.