3-1/2" Floppy Market Cornered

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Thu May 22 15:16:36 2003

> 3.5":
> Find one of each that are known, and labeled by the
> manufacturer. Sometimes the labeling will refer to the UNFORMATTED
> capacity and say 1M v 2M.
> Find the write protect hole. Notice that on the HD diskette, there is
> another similar hole in one of the other corners.

That, surely is a reliable method for name-brand disks.

> 3":
> I don't think that there are any density differences, but single and
> double sided diskettes are different. I don't remember the difference -
> holes?

This is the confusing one IMHO. All 3" disks are double sided, but some
drives are single-head and use the disks as 'flippies'.

However, Amstrad, who were the major user (at least in the UK) of 3"
disks fitted 40 cylinder single-head or 80 cylinder double head drives to
their machines. With the result that 80 cylinder-capable disks were often
called 'double sided' and 40-cylinder ones 'single sided'.

But 40 cylinder double-head drives exist (I have one on my CoCo), and
obviously from the above they are reliable using so-called 'single-sided'
disks.

AFAIK the pattern of holes and notches is the same in all disks.

-tony
Received on Thu May 22 2003 - 15:16:36 BST