[Coco] RE: [Color Computer] Re: using Tandy FD drives in a PC

Mike Pepe lamune at doki-doki.net
Thu Jun 3 19:03:35 EDT 2004

The reason your drives are both being selected at the same time has to do
with a quirk of PC floppy cabling. It has nothing to do with the age or cpu
type or speed of the PC you're using.

All PC floppies are shipped from the factory set as "drive 1". (or is it 2?
I'm not sure now) The twist in the cable determines which actual drive
select line goes to the proper drive. Thus, you plug a drive into the first
connector and it's "A", the second is "B".

There are two ways to solve this:

1- use the PC cable, but set your CoCo drive to DS1 (or 2, if 1 doesn't
work) or:

2- use a straight through cable without the twist. Set your A drive to DS0
and your CoCo drive to DS1

Don't forget to remove or disable the termination on the drive that's not at
the end of the chain.

I'm pretty sure the FD-501 drive has drive select jumpers, but if it does
not, as you discovered, you can connect it as the only drive and it should
work in any PC. You may need to experiment with the twisted/non-twisted
sockets and whether the PC thinks it's drive A or drive B.

> -----Original Message-----
> From: Charlie [mailto:chazbeenhad at hotmail.com]
> Sent: Thursday, June 03, 2004 8:57 AM
> To: ColorComputer at yahoogroups.com
> Subject: [Color Computer] Re: using Tandy FD drives in a PC
> --- In ColorComputer at yahoogroups.com, Robert Emery
> <theother_bob at y...> wrote:
> > >   ----- Original Message -----
> > >   From: Charlie
> > >
> > >   I could NOT get the FD-501 drive to work as drive B on any of 3
> > >   different PCs last night.
> > >
> > >   1st of all, as it was with a 1.44 floppy on the ribbon cable
> both
> > >   drives acted as A at the same time.
> > >
> > >
> > >   Any tips on getting this 180K fd-501 disk to work on a PC?
> > >
> > >   -Charlie
> >
> > --- sadolph <sadolph at m...> wrote:
> > > There is a resistor network that needs to be uninstalled, on the
> b drive I
> > > believe.
> > >
> > > Also, you have to jumper the drive to be drive b.  there are
> usually markings
> > > that identify which jumper it needs to be.
> > >
> >
> > If your cable allows it, try putting both drives on the same side
> of the twist
> > (if you can't find the DS jumpers.) The terminating resistor
> network should be
> > removed if it's not the last drive on the cable.
> >
> > Bob
> >
> Yesterday I did get the FD-501 drive working in a Asus A7a-266 mobo
> with an Athlon 900 cpu running DOS.
> My FD-501 drive has no jumpers at all. There is a spot that says DS0
> DS1 DS2 DS3 but there are no jumper pins, the DS0 and DS1 are
> soldered together. Regardless, It was working as a single drive A. Of
> course I told the bios it was a 360K floppy, but I got no error and
> Anadisk was writing and reading from the drive just fine.
> Still though, at the COCO the disks were no good. No DIR, nothing
> just IO errors. I took the FD-501 drive out of the PC and threw in
> one of the 360K drives I use on my COCO and got the same results.
> So maybe it has to do with the disk controller on the mother board.
> Or, a combo of both .....
> I guess I'll have to search around here at work for the oldest system
> I can find with a 486 or 386 cpu.
> -Charlie
> Brought to you by the 6809, the 6803 and their cousins!
> Yahoo! Groups Links

------------------------ Yahoo! Groups Sponsor --------------------~--> 
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!

Brought to you by the 6809, the 6803 and their cousins! 
Yahoo! Groups Links

<*> To visit your group on the web, go to:

<*> To unsubscribe from this group, send an email to:
     ColorComputer-unsubscribe at yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:

More information about the Coco mailing list