Actually, in the current "standard" for IBM-style implementation of the FD
cable, there is a 3rd drive select. The fact that the selects aren't used in
the normal way is no surprise, but the result is that you can have 2 floppy
drives and a tape drive, but you can't use the floppy drives while you are
running the tape drive because there's no telling who uses that 3rd select
signal for something else.
Dick
----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Thursday, February 14, 2002 3:12 PM
Subject: Re: Drive inventory
> >
> > On Thu, 14 Feb 2002, Tothwolf wrote:
> >
> > > That would work well if all the tape drives that use the floppy
> > > interface followed the rules, but not all do. I guess it would be
> > > possible to build a board with some logic chips that could isolate
> > > individual drives from the bus, but I think it would be much easier for
> > > now to only connect one drive at a time.
> >
> > Can you elucidate? How can a floppy interface tape drive not follow the
> > rules and still work?
>
> Actually they _have_ to break the rules. If they followed the rules,
> they'd appear as a floppy drive, and you'd be limited to the tape drive
> and one floppy drive on the cable. Most people want(ed?) to have 2 floppy
> drives + the tape drive, so the tape drive has to break the rules for
> drive selection. It can't simply use one of the drive select lines.
>
> -tony
>
>
Received on Thu Feb 14 2002 - 19:24:43 GMT