Date : Sun, 26 Apr 2009 16:11:23 +0100
From : bbcmailinglist@... (Ian Wolstenholme)
Subject: A thought for Domesday
There's plenty on the Domesday discs which can be accessed using only
the data on the discs rather than the video frames, for instance the essays
on the National Disc, the local area write-ups on the Community Discs and
all manner of statistical data which can be displayed with graphs and
charts.
It's not the same without the video frames, of course, but you could have
a sort of text-only Domesday running on a BBC if you had a copy of the
data from the discs stored locally on a hard disc or flash card (or even
possibly over Econet). You would need a way to bypass anything that
the software might try to do which goes to VFS which isn't a filing system
operation, such as displaying a frame or a video mixing command.
My idea about this was to have a "dummy" version of VFS running, which
just ignores any commands like *PLAY, *VOCOMPUTER and all that sort
of thing, and passes anything relating to disc access to ADFS.
Unfortunately, when I tried to do this a while back, my dummy ROM
ignored any * command issued on the Beeb so it didn't work, but I'm sure
somebody else could do better!
The next major obstacle is the sheer size of the files on the Domesday
discs. Some of the files are over 100MB and there aren't any BBC
filing systems which can cope with files of this size (unless the patched
ADFS allows files this big on flash card drives). The only solution I
could think of to this was to put it on a Level 4 Econet file server on an
Archimedes, which can cope with disc capacities big enough to hold one side of
the Domesday discs and with files the size of the Domesday files.
I got as far as copying all the data contents of the Domesday Discs onto
my MDFS in 8MB chunks with the ARM7 co-processor. If I could get round
to copying these onto my A5000 and reassembling the chunks into the
original files, I would be able to try it out.
Certainly doing *RUN !BOOT whilst logged on to the MDFS partition
containing the Domesday boot file gets as far as the blue "Domesday
System loading" caption.
But even this would be dependent on the Domesday software using official
filing-system-independent OS calls and commands to access the discs to
enable it to be run from Econet. If it expects a certain bit of data to be
xxxx bytes in from the beginning of one of the huge files then there might
be a chance, but if it expects that certain bit of data to be on sector xxx
of the disc then there isn't much hope I wouldn't think.
Best wishes,
Ian
----- Original Message -----
From: Joel Rowbottom [mailto:joel@...]
To: bbc-micro@...
Sent: Sun, 26 Apr 2009 10:04:38 +0100
Subject: Re: [BBC-Micro] A thought for Domesday
--On 26 April 2009 09:59:44 +0100 Mark Usher <mu.list@...> wrote:
>> I'll write a proper report at http://blog.joel.co.uk when I
>> get chance, but for the moment I need to wire my Econet back
>> up and set the Northern side of the Community Disc copying to CF :)
>
> If a patched ADFS were used in a Domesday machine
It'd have to be a patched VFS, and I suspect you'd have to patch it for
more than filesystem access since it also controls the genlock.
Interesting idea, mind :P
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