Subject: Re: ROM Maps
To: Daniel R. Killoran,Ph.D. <drk@shore.net>
From: Dave Huang <khym@bga.com>
List: port-mac68k
Date: 03/01/1999 12:29:57
On Mon, 1 Mar 1999, Daniel R. Killoran,Ph.D. wrote:
> This is a distinction without a difference - on the Mac, the hardware
> fetches the address from the trap table when it hits an A-instruction.
> There is no practical difference between this and a jump to a transfer
> table except that the registers get saved.

True, but that's not what I was talking about... the discussion was
about whether the address of ROM routines have moved, and you said they
haven't, since that would break existing programs. As others have
mentioned, they _have_ moved around. For example, on a Mac Plus, _Pack0
is 0x17032 bytes past ROMBase. On an AV Mac, it's at 0x3a434 bytes past
ROMBase. It's at 0x1a0a2 past ROMBase on a Mac SE. Obviously, one can't
jsr to ROMBase+0x17032 and have it work on every Mac.