Re: //e: How Do Slots Work?

[david@uow.edu.au (David Wilson)]

Dave Lowry <lowry@htc.honeywell.com> writes:

>How do the Apple //e slots work?  Are they memory mapped?  Do the ROMs
>on the cards
>contain executable code, or just parameters?  Thanks!

Slot #		Device Select	ROM Select	Shared ROM Select
------------------------------------------------------------------
1		C090..C09F	C100..C1FF	C800..CFFF
2		C0A0..C0AF	C200..C2FF	C800..CFFF
3		C0B0..C0BF	C300..C3FF	C800..CFFF
4		C0C0..C0CF	C400..C4FF	C800..CFFF
5		C0D0..C0DF	C500..C5FF	C800..CFFF
6		C0E0..C0EF	C600..C6FF	C800..CFFF
7		C0F0..C0FF	C700..C7FF	C800..CFFF

The ROM space typically contains executable code with an entry point at
CN00 called when input (or output) occurs after IN#n (or PR#n) command
has been used. The device space, being only 16 bytes in size, is typically
used to select registers on I/O chips (like ACIAs, PIAs etc). The C800..CFFF
space is available to all slots provided all the cards play by the rules
(all cards disable that ROM space when CFFF is accessed, the card in Slot N
enables access when location CNXX is referenced).

ProDOS block device controllers, Smartport controllers and Pascal 1.1 protocol
cards have entry points in addition to the CN00 one used by BASIC and
the initial slot scan to find a bootable device.
--
David Wilson  School of IT & CS, Uni of Wollongong, Australia  david@uow.edu.au