4 Jan
2012
4 Jan
'12
7:24 p.m.
On 1/3/2012 2:32 PM, MikeS wrote:
Date: Sat, 31 Dec 2011 13:24:36 -0800
From: Josh Dersch <derschjo at mail.msu.edu>
Subject: Re: Looking for 8080/Z80 BASIC
On 12/31/2011 12:15 PM, MikeS wrote:
Actually, the board occupies everything from $8000 on up, if the manual
is to be believed ("The 64FDC appears on the S-100 bus as a 32K memory
card..."). Since the ROM is at most 8K in size that's a bit suboptimal
:). (And it starts at C000 for apparently arbitrary reasons...)
----- Reply:
> Just curious:
> Does your memory configuration support swapping out the RDOS
> boot/monitor
> ROM?
Not at the moment, I haven't quite worked out
if this can be made to
work
properly with non-Cromemco memory boards. The 64FDC manual suggests
"Set[ting] the switches on the RAM board(s) so that memory from 8000h to
FFFFh is disabled..." which implies that the boards must support some
way
of re-enabling the memory via software (for when the FDC's ROM is
disabled
via a write to port 40h).
I'm wondering if this board isn't really
optimal for this setup -- it
seems very geared toward having a complete Cromemco setup, which I do
not
have.
----------------
I don't see why it would be a problem; the RDOS boot/monitor ROM lives at
C000 so it should work with 48K RAM even if you don't disable it; ISTR that
some folks simply connected the ROM chip select to the Phantom line if
they
had non-bankable memory and wanted to switch it in and out. And of course
the ROM can be completely disabled as well.
How does the "phantom" line work? I see references to this in some of
my S-100 manuals but I'm not clear how it works (who raises/lowers it,
when, etc...)
It controls up to four total 5.25 and/or 8" drives with write precomp,
has
an RS-232 console port and a pretty good monitor with the usual memory
and
disk manipulation, some basic diagnostics, etc.; not a bad card IMO. And
it's fairly well documented.
It is pretty nice, the documentation is fairly decent (though seriously
lacking in documentation of error codes as I'm finding while trying to
get it to boot a floppy :)).
Thanks for the help!
- Josh