Date   : Tue, 29 Aug 2006 16:05:37 +0100
From   : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Re: writing and reading on 3.5 floppy

Just to wade into this debate about getting 3.5" floppy drives
working on the Beeb:

As I have discovered this afternoon, something to check is that Pin 1
of your (twistless) cable is going to Pin 1 on the floppy drive itself.

It may sound extremely obvious to say this but some of these drives
(I am looking at 2 Sony MPF520 drives) have the plastic housing
of the connector "upside-down" so that when you plug it in lining
up the notch, pin 1 of the lead is in fact connecting to pin 34 of the drive!

Looking at the drive PCB on these drives, there is a notch cut out of the
board in the correct position but somebody very clever at Sony has
decided to fix on the header the other way up.

So if the drive motor is running all the time or the drive light is illuminated
all the time, this is something to check.

Best wishes,



Ian
 
----- Original Message -----
From: Pete Turnbull
To:  bbc-micro@...
Sent:  Tue, 29 Aug 2006 00:50:47 +0100 (BST)
Subject: Re: [BBC-Micro] Re: writing and reading on 3.5 floppy

On Aug 28 2006,  1:06, Jonathan Graham Harston wrote:
> Mike Howard <aixguru@...> wrote:
> > Wright, Chris wrote:
> > > the drive number but the 3.5" drive doesn't. The PC lead that I
have for
> > > the 3.5" drive has a twist in it for a couple of wires. Is this
part of
> > > the drive selection (when connected to a PC) ?
> >
> > I'm no expert on the workings of floppys & drive selection. I
believe
> > though, that the twist in a PC cable forces the drive to drive 0
(zero)

No, it forces it to what would be drive 2, if a Beeb used all the
possible drive selects (0,1,2,3).  But a Beeb doesn't have four drive
selects; it only has two, and what a Beeb using DFS regards as drives 2
and 3 are just the other sides of drives 0 and 1.  A modern PC (or
compatible) also has but two possible drive selects on a normal
interface, but it uses 1 and 2 (instead of 0 and 1).

> See thread on here last October subject "Floppy pinouts and
> twists", specifically a post from Pete Turnbull on 25-Oct-2005.
> See http://nelsonit.net/~jon/BBCMicro/2005/10

Also worth a look is Andrew Benham's post from a couple of days
earlier, entitled " Floppy cables: the answer".

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York