Re: A few technical q's from an apple newbie

["josephoswaldgg@hotmail.com" <josephoswaldgg@hotmail.com>]

I'm not clear on what version of the II you are trying to implement. It
might be best to go for (at least start with) one of the II/II+ models,
with 48k RAM because all the logic was synthesized with pure TTL, and
you can get schematics from various sources (someone has the old 1978
"Redbook" reference manual scanned into a PDF).

The IIe and later models had some GAL and custom ASICs that were not
publicly documented; at best, people like Jim Sather reverse engineered
them. The softswitch behavior got more complicated with later models as
well. DOS 3.3 games like Lode Runner usually can run in a 48K original
II just fine.

I don't have a reference manual handy, but I believe the INTCxROM
softswitch is used to control whether $c100..$cfff was mapped ROMS on
expansion slots or the expanded ROM space in a IIe that contained, as I
recall, diagnostic routines, 80 column firmware support, and maybe some
other miscellaneous code. Yet another way, along with its built-in
language card & 64k expansion support, readable soft-switches, VBLANK
connections, etc., that a IIe is more complicated than a II/II+. About
the only thing simpler in a IIe is the lack of memory config jumpers.