Date   : Sat, 31 Jul 2010 00:40:10 +0200
From   : rick@... (Rick Murray)
Subject: Why did Acorn ADFS only allow 640KB on a floppy?

On 30/07/2010 23:52, Phill Harvey-Smith wrote:

> I don't get what you're getting at 720K is cirtainly possible with an 8
> bit micro,

Pretty much any format the controller can work with is *possible*. :-)


I've poked around the datasheet (TMS279X), and I am wondering if it 
might not be a timing issue relating to the actual formatting of the 
disc. There are quite a lot of places where repeat values are written, 
and if you bash the hardware you might be able to squeeze in an extra 
sector or two?

That doesn't mean you *should* - and I suspect the fact that all of the 
common DFSs and ADFS ( http://mdfs.net/Docs/Comp/Disk/Format/Formats ) 
were of the smaller size might indicate issues with the extra sectors?


Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...