Secondary Floppy Controllers

[John]

Hi,

I would like to add a 2nd floppy controller card to an old PC to connect up
a 3rd floppy drive, but have got stuck.

First query is to do with the settings on most of the ISA multi-function
controller cards (eg IDE / floppy / LPT / COM cards). Some of the ones I
have allow the floppy controller to use a secondary I/O address, such as
this card:

http://www.embeddedlogic.com/TH99/c/C-D/20857.htm

which can use either 3F0H (primary address) or 370H (secondary address). The
primary address is already used by the motherboard's floppy controller (for
the first 2 floppy drives) and I can't find a way under DOS to use the
secondary address - so how can this be used in DOS? I've looked for drivers
without much luck.

The other approach seems to be to find an old ISA card with a built in BIOS,
such as this one:

http://www.jdr.com/interact/item.asp?itemno=MCT-FDC-HD4

Looking through Total Hardware 99 (above) these cards were made for the IBM
XT & clone aftermarket around 1985-90 to allow PCs with 360K/720K drives to
use newer 1.4M high density drives (these are also mentioned in the Tandy
1000 FAQ).

So my second query is has anyone got a similar old ISA card (with a BIOS
that supports the floppy controller) kicking around there spares box?

Please post here or e-mail at john_pc2004 at yahoo dot co dot uk

Thanks,
John

[Gereon Wenzel]

Hi John,

Post by John
I would like to add a 2nd floppy controller card to an old PC to connect up
a 3rd floppy drive, but have got stuck.

There was athread about this topic about half a year ago.

Post by John
First query is to do with the settings on most of the ISA multi-function
controller cards (eg IDE / floppy / LPT / COM cards). Some of the ones I
have allow the floppy controller to use a secondary I/O address, such as
http://www.embeddedlogic.com/TH99/c/C-D/20857.htm
which can use either 3F0H (primary address) or 370H (secondary address). The
primary address is already used by the motherboard's floppy controller (for
the first 2 floppy drives) and I can't find a way under DOS to use the
secondary address - so how can this be used in DOS? I've looked for drivers
without much luck.

The mainboard BIOS just supports two floppies,
you will have to need drivers to get the second controller recognized.
I got an sdrive.sys than can be supplied, but didn't test myself it yet.
(The driver is from http://www.pop-brb.de/download/treiber/exsys/ide.zip
which is a 4.55MB archive)
Intelligent OSs like linux may support the second controller from
scratch?
(At least it does for second IDE without BIOS support)

Post by John
The other approach seems to be to find an old ISA card with a built in BIOS,
http://www.jdr.com/interact/item.asp?itemno=MCT-FDC-HD4
Looking through Total Hardware 99 (above) these cards were made for the IBM
XT & clone aftermarket around 1985-90 to allow PCs with 360K/720K drives to
use newer 1.4M high density drives (these are also mentioned in the Tandy
1000 FAQ).
So my second query is has anyone got a similar old ISA card (with a BIOS
that supports the floppy controller) kicking around there spares box?

I have one of these, but it's still in use.
These controllers were common to connect HD drives to XT class machines.
Lot of older XT BIOS supported 360K drives only.

Gereon

[John]

Post by Gereon Wenzel
Hi John,

Post by John
which can use either 3F0H (primary address) or 370H (secondary address). The
primary address is already used by the motherboard's floppy controller (for
the first 2 floppy drives) and I can't find a way under DOS to use the
secondary address - so how can this be used in DOS? I've looked for drivers
without much luck.

The mainboard BIOS just supports two floppies,
you will have to need drivers to get the second controller recognized.
I got an sdrive.sys than can be supplied, but didn't test myself it yet.
(The driver is from http://www.pop-brb.de/download/treiber/exsys/ide.zip
which is a 4.55MB archive)

Thanks, yes I tried this but it didn't recognise the drives on my card, it
looks like a driver for a specific controller card rather than a generic
one.

Lots of useful tips here:

http://www.seasip.info/VintagePC/floppies.html

so thanks to the author!

Post by Gereon Wenzel
Intelligent OSs like linux may support the second controller from
scratch?
(At least it does for second IDE without BIOS support)

Yes plenty of references in Linux HOWTOs on secondary floppy controllers, a
bit OTT to me as I have never installed Linux on anything other than a
Pentium Xeon 2.7GHz box :-) at work :-(

Regards,
John

[Rick]

Post by John
Hi,
I would like to add a 2nd floppy controller card to an old PC to connect up
a 3rd floppy drive, but have got stuck.
First query is to do with the settings on most of the ISA multi-function
controller cards (eg IDE / floppy / LPT / COM cards). Some of the ones I
have allow the floppy controller to use a secondary I/O address, such as
http://www.embeddedlogic.com/TH99/c/C-D/20857.htm
which can use either 3F0H (primary address) or 370H (secondary address). The
primary address is already used by the motherboard's floppy controller (for
the first 2 floppy drives) and I can't find a way under DOS to use the
secondary address - so how can this be used in DOS? I've looked for drivers
without much luck.

DOS is not aware of anything but the primary floppy controller
hardware address. Anything else used would require drivers. But as
you have found out, although a lot of multi i-0 cards were produced
that allowed you to configure the controller for a secondary
address, no drivers seem to have been made that supported the
scenario.

Post by John
The other approach seems to be to find an old ISA card with a built in BIOS,
http://www.jdr.com/interact/item.asp?itemno=MCT-FDC-HD4
Looking through Total Hardware 99 (above) these cards were made for the IBM
XT & clone aftermarket around 1985-90 to allow PCs with 360K/720K drives to
use newer 1.4M high density drives (these are also mentioned in the Tandy
1000 FAQ).

Yup. That works fine. As long as you can disable any other floppy
controller in the system. It still needs to use the primary address
to be functional.

Post by John
So my second query is has anyone got a similar old ISA card (with a BIOS
that supports the floppy controller) kicking around there spares box?
Please post here or e-mail at john_pc2004 at yahoo dot co dot uk
Thanks,
John

Afraid not - I'm holding onto mine. But you may find an alternative
to the expensive MCT card. Try a search on any of the following:
"Ably Tech Unique FDC" The Ably Tech is a 4 drive contoller with
BIOS as well. It's no longer available as a new item.

[Martin Slaney]

Post by John
Hi,
I would like to add a 2nd floppy controller card to an old PC to connect up
a 3rd floppy drive, but have got stuck.
First query is to do with the settings on most of the ISA multi-function
controller cards (eg IDE / floppy / LPT / COM cards). Some of the ones I
have allow the floppy controller to use a secondary I/O address, such as
http://www.embeddedlogic.com/TH99/c/C-D/20857.htm
which can use either 3F0H (primary address) or 370H (secondary address). The
primary address is already used by the motherboard's floppy controller (for
the first 2 floppy drives) and I can't find a way under DOS to use the
secondary address - so how can this be used in DOS? I've looked for drivers
without much luck.
The other approach seems to be to find an old ISA card with a built in BIOS,
http://www.jdr.com/interact/item.asp?itemno=MCT-FDC-HD4
Looking through Total Hardware 99 (above) these cards were made for the IBM
XT & clone aftermarket around 1985-90 to allow PCs with 360K/720K drives to
use newer 1.4M high density drives (these are also mentioned in the Tandy
1000 FAQ).
So my second query is has anyone got a similar old ISA card (with a BIOS
that supports the floppy controller) kicking around there spares box?

Dunno if it would work - but I have a ISA card with floppy interface
that shipped with tape drives as a "floppy accelerator" - but the
interface is definitely floppy standard .... won't be seen by the BIOS
though ...

[Tony Ingenoso]

There's a number of aftermarket PC/XT FDD controllers that can handle 4 drives. GSI is one I remember. Some can do 1.44 and even
2.88 drives.

That being said, if you've got an original IBM PC/XT FDD controller, that odd looking plug on the back of it *IS* in fact used for
hooking up external drives. That controller (and the PC/XT BIOS) directly support up to 4 FDD's.

I had an XT long ago I'd lashed up 4 internal half heights into. I fab'd a cable to go from the external plug and just ran it back
inside the case to the extra two drives.

Post by John
Hi,
I would like to add a 2nd floppy controller card to an old PC to connect up
a 3rd floppy drive, but have got stuck.