22 Jan
2003
22 Jan
'03
7:48 a.m.
On Jan 22, 12:45, dave(a)cirt.net wrote:
different
Quoting pete(a)dunnington.u-net.com:
> On Jan 18, 16:16, Philip Pemberton wrote:
>
> > Finally, does anyone know how some discs were formatted so they
were
> > compatible with 40-track and 80-track disc
drives?
> The way Acorn did that with things like the
Master 128 Welcome Disc was
to
> make all the directory entries (on track 0) point
to tracks between 5
and
> 9, and 20 and 39. Track 20 on a 48-tpi drive is
where track 40 would
be on
a 96-tpi
drive:
One has to be very careful with the formatting - there where several FS formats - some with varying compatibility. (Talking
about the file
system
side here) The Master welcome disc used ADFS which was
slightly more
advanced
than the more common DFS that was used on the earlier
Acorns.
Yes, I'm aware of that. The Master Welcome Disc appears to the system as
an ADFS S disc (S means "small format", 160K), ie as 40-track single-sided
disc. It just happens to be made in such a way as to be readable in
40-track and 80-track drives.
I created a few discs like that at the time. I did it by hand, but I
believe eventually someone made a utility or ROM to do it.
Now if you think that's wierd, how about the disc I have (also for a BBC)
that has three separate sets of data on it, all in DFS format?
--
Pete Peter Turnbull
Network Manager
University of York