From: "Adrian Graham" <witchy at binarydinosaurs.co.uk>
31/4 drives were used on the old Amstrad word processing
machines (forget the number - do any of the other UK members know?
They were (I think Hitachi) 3" drives that were going to be 'the next big
thing'. The likes of Amscrap, Sinclair and Tatung used them probably
because
the 'new' sony drive was more expensive.
Double sided disks were used to
give 160k per side, you had to turn the disk over to get at the other
side.
Most of the amstrad machines on my website feature the
3" drive but I've
just checked and most of the pictures of the drive itself are pretty poor
to
say the least!
I've got a PCW series machine downstairs if anyone wants pictures but
they're found all over the web :)
Oh well I was close! I knew the Amstrads used something odd, but it's been
20 years since I used one....
Jim.