9 Oct
2005
9 Oct
'05
7:52 a.m.
On Sat, 8 Oct 2005 14:25:41 -0700
Tim Mann <tim at tim-mann.org> wrote:
On Sat, 8 Oct 2005 03:25:49 -0500 (CDT),
cctech-request at classiccmp.org
wrote:
One thing I am wondering is if an 8-bit floppy controller card (the ones
Message: 22
Date: Fri, 7 Oct 2005 21:51:09 -0700
From: jim stephens <james.w.stephens at gmail.com>
Subject: Re: TEAC FD-55GFR = Quad Density?
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Message-ID:
<ae0bc2000510072151o541c0ad3u8dbc114f37216beb at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
<snip>
I built a new machine around an EPoX 9NPA nForce 4 motherboard and
found out to my surprise that it was only capable of running one
floppy drive. In my case the BIOS provides no way to enable a second
drive, so at least it's consistent. Having a BIOS that lets you put
in settings for a second drive when the hardware doesn't support it
would really be a screwup.
EPoX makes schematics available, so I downloaded one and studied it to
try to confirm whether there really was no way to get a second drive
to work. It turns out the super-IO chip they use to run the floppies
and several other system functions (fan control, temperature sensors,
serial and parallel ports, etc.) has only a limited number of pins.
Several have multiple functions, and the motherboard designer has to
select which function he wants to use for each pin and do without the
others. EPoX chose to use the pins that could have driven the second
floppy's motor-on and drive select for other functions (I forget what
offhand). So those pins are no-connects on the floppy cable.
As a small compensation, it's possible to reconfigure the parallel
port as an external floppy connector. If you do that, you can put two
drives on it. (Whoopee.)
This all is not a huge deal for me since I can pop a Catweasel card
into the machine if I really want more floppies in it, but it's a bit
annoying.
<snip>
Actually, I am still slowly getting over my long painful struggle
to get two floppy drives enabled on a Dell Optiplex system.
There's support for a second floppy in the BIOS but it appears the
hardware support is entirely missing. I had to just do away with
the 3-1/2" disk to get a 5-1/4" disk installed in one of my (many,
since I get them for < $5 all kitted out with Pentium III
processors) beloved (!!??!!) Optiplex boxes. Was there THAT much
savings in not including hardware support for two floppies, DELL?
Why not patch settings for the second drive out of the BIOS so we
don't pound our heads against the wall trying??
I'm curious about the comment about second drive support missing.
I
am curious why the addition of a proper multiheaded cable doesnt
fix this?
they actually dont drive the drive select in the cable? from the PC-XT generation, which didn't have floppy
IO on the
motherboard) could be modified (if needed) and contrived to work in a
more modern system that still has the ISA bus. If the particular I/O
locations are being used, simple cuts and adds could re-direct the I/O
ports. This would give the enterprising programmer a 765 controller
with relevant hardware to plug additional drives into. The original
PC-PC/XT controller is fully documented in the TechRef, and even has all
the cabling in place to support four floppies.
--
Tim Mann tim at tim-mann.org http://tim-mann.org/