Date   : Fri, 30 Jul 2010 22:49:10 +0100
From   : adsb@... (Andrew Benham)
Subject: Why did Acorn ADFS only allow 640KB on a floppy?

On 30/07/10 22:19, Steven Flintham wrote:

> I was so sure I had not made this up :-) I just went and looked in a 
> copy of The Micro User (July 1987, FWIW). I have a Watford Electronics 
> ad in front of me saying their DDFS "gives 80% more storage per disc in 
> double density mode, P.S. - Please note that not all DDFSs are capable 
> of providing the full 80% storage increase", and I make that 720K for a 
> double-sided 80 track disc (400K with standard DFS, 400*1.8=720). Am I 
> being dense (no pun intended!) or is the ad misleading?

IIRC the Watford DDFS shoe-horned 18 256-byte sectors onto each track
rather than Acorn's 16.

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

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