Date   : Fri, 30 Jul 2010 20:44:55 +0100
From   : mlist@... (Steven Flintham)
Subject: Why did Acorn ADFS only allow 640KB on a floppy?

I was flicking through some old copies of The Micro User last night and 
this question occurred to me, not for the first time. I am fairly sure a 
lot of the third party double density DFSs let you put 720KB on a 
floppy. So why did Acorn not do the same with ADFS? Is there some 
technical reason (reliability? I never used a double density DFS myself 
so I have no experience), or was it just 'one of those things'?

(For that matter, why did no one push it to 800KB in a 'normal' BBC 
filing system? The Master FDC at least must have been capable of it 
because the Master 512 used an 800KB format.)

Steve

P.S. I tried to find a manual or something to confirm the existence of a 
DDFS offering 720KB, but surprisingly failed - none of the documentation 
or reviews I turned up bothered to mention the capacity offered. So 
maybe I'm imagining this...