Re: GS ROMS

[tkav@mcontent.apana.org.au (Tony Kavadias)]

> I would like to know how the firmware gets from the ROM
> (bank FF) to its location in bank 00.  Is it shadowed (from
> bank FF), is it copied (to bank 00) or is it copied (to bank
> E0) and then shadowed to bank 00. Perhaps there's another
> technique of which I am unaware?

It is explained in the Apple IIGS Hardware Reference Manual;
the ROM between $FEC000 and $FEFFFF (bank $FE) is shadowed
to bank $00 (guess at what addresses!).

"Shadowing" means that any address between $xxC000 and $xxFFFF
in bank $00 and $01 the CPU tries to access will actually
access memory addresses in banks $FE and $FF respectively.

I hope this is clear to you!  If not, please refer to the
Apple IIGS Hardware Reference Manual (2nd Edition).

---

#include <signature.f>

static void
tony_kavadias(shomega_limited, maccontent_bbs)
      struct com  shomega_limited;
      struct org  maccontent_bbs;
{
      /* Comments are STRICTLY my own, nobody elses */
      tkav@allgfx.agi.oz.au = internet_addr(shomega_limited);
      tkav@mcontent.apana.org.au = internet_addr(maccontent_bbs);
}