Date   : Mon, 24 May 2004 16:53:29 +0100
From   : Angus Duggan <angus.duggan@...>
Subject: Re: Tube / Master Coprocessor question

Mike Tomlinson writes:
>The lower 4 bytes form the actual address; if the upper 2 bytes are FF,
>the code is loaded/run in the  I/O processor, if they're 00, it's
>loaded/run in the second processor.  Can't recall offhand what values
>other than FF or 00 mean, if anything (my AUG's in the loft.)

Actually, 0xFFFFxxxx is reserved for the I/O processor. All other addresses are
in the Tube. The 32016 tube supported more than 64k memory, the 6502 one
doesn't, so addresses above 0xffff drop the upper bytes.

DNFS variants only support 18-bit addresses, rather than store a full 3 bytes
for each.

a.