Date   : Wed, 26 Oct 2005 22:15:28 +0100
From   : Andrew Benham <adsb@...>
Subject: 3.5" PC floppy drives with the BBC

Two items for the fledgling 'database' of 3.5" PC floppy drives.

All tests done with "straight through" cables, as I don't believe
the PC floppy cable with the twist in it stands a hope of working
with a BBC.

1/. Sony MPF420-1

     Initial tests were bad, until I noticed that the IDC socket
     has the polarization cutout on the wrong side.  The PCB has
     the cutout on the right side (cutout same side as odd numbered
     pins), but the IDC socket has it on the wrong side.  Don't know
     whether they're all like this (I'd expect this from some cheap
     Taiwanese outfit, but not from Sony).

     Working around that, works as BBC drive 1 as removed from PC.

     There's a block, labelled "COR1", of 15 pins in a block of
     5 x 3 (labelled 1-15).  Changing the jumper on 10-15 to be
     on 5-10 switched it to work as BBC drive 0.  Don't know what
     all the pins are for - but I could try the Avo on them.

2/. Sony MPF920-E

     Works as BBC drive 1 as removed from PC.

     After a bit of dismantling, it looks like it would need a
     zero ohm chip resistor removed from one pair of pads and
     moved to another pair to change the drive number.
     As the chip resistor is no doubt glued to the board as
     well as soldered to the pads, it would be easier to make a
     "BBC twist" cable to get this drive to work as BBC drive 0.

Hope this info helps.

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"