Date   : Sun, 22 Apr 2007 16:47:39 +0100 (BST)
From   : debounce@... (Greg Cook)
Subject: Z80 coprocessor cursor keys

On 21 Apr 2007 14:55:58 +0100, Jonathan Graham Harston
<jgh@...> wrote:

> >Message-ID: <891909.46162.qm@...>
>  
> Greg Cook <debounce@...> wrote:
> > J.G.Harston wrote:
> > 
> > > Challenger introduced 640K double density disks.
> > 
> > Erm, 720K.  :-)  640K was ADFS.
>  
> 2 sides * 80 tracks * 16 sectors * 256 bytes = 655360 bytes
>  
> Ok, yes tracks 0-2 were single density, so
>  
> 157 * 16 * 256 + 3 * 10 * 256 = 650752 bytes = 635.5K

Source please?  I was under the impression that Challenger discs were
identical to DDOS discs[1][2].  Anyway, there was DDOS and quite a few
other formats that offered 720K capacity.

Greg Cook
debounce@...
<http://homepages.tesco.net/~rainstorm/>

[1]DDOS Challenger manual (MS Word)
<http://www.astro.livjm.ac.uk/~bbcdocs/hardware/OpusDDOS.zip>
[2]Challenger disc copier & reader, BBC PD disc 109, files :2.P.D2D and
:2.P.LTRACKS.  Formerly at <http://www.8bs.com/pool/bbc/bbc109.zip>



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