Date   : Tue, 23 Mar 2010 19:43:58 +0000
From   : afra@... (Phill Harvey-Smith)
Subject: Re-using floppies

Anders Carlsson wrote:
> Phill Harvey-Smith wrote:
>> Then there's flippy disks which have two sync holes so you can flip
>> them over, I seem to remeber these being used on the Commodore PET.
> 
> Well, don't you need a second sync hole (in the jacket) to use
> flippies with a single sided drive on the BBC Micro too?

Indeed, it's just that they seemed to be popular with the commodore 
crowd from what I remember from the early 80s.

> I am not sure if any of the 35 track drives (2040, 3040, 4040, 2031)
> use the sync hole, but I suppose you need a second sync hole to flip
> a disk in the 8050.

No I remember repairing a VIC floppy drive a couple of years bac and 
being supprised that it didn't have any sync sensor, I guess it myst 
sync up by reading the disk, wonder how it detects the beginning of the 
track when formatting, I guess it just starts writing and writes a fixed 
number of sectors.

Cheers.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.