Date   : Fri, 02 Jun 2000 04:02:27 -0700 (PDT)
From   : Thomas Harte <t.harte@...>
Subject: Wave level tape encoding & adfs disk format

The next targets for my emulator are to properly support tape files and
possibly loading over the soundcard, and to finish the dfs2adfs (it actually
does more than that, but no matter) converter such that all the bodged
'Electron' games on the 'net are loadable.

However, two obstacles stand in my way - I have been unable to find out how
the tape files are encoded at the sound wave level, and I haven't been able
to find a document on the adfs catalogue format. Although I have a hard copy
at home which'll be no problem in about four weeks when I finish uni for
summer, and I will of course type that up if no copy does exist online.

For the tape format I've really only checked the BBC and BBC Master AUGs.
Perhaps I should find a document about the ACIA? If so, can anyone tell me
what settings the BBC uses with this chip (if applicable), to save me having
to read up further on information I really don't actually need to know? The
Electron uses a cassette interface hard wired to read the same encoding as
the BBC, so none of the ACIA stuff is applicable.

As for the ADFS, I have checked every file on the BBC Documentation source
which says 'disk' or 'dfs' anywhere in the title, but to no avail. The
regulr DFS and Watford DFS62 formats are documented in a file principly
about the Watford DFS62, but that is all I have found. Does anyone happen to
know of a less obviously titled document, possibly on another topic, which
happens to mention the format? I'm talking about at the level of what the
Electron or BBC sees, I'm not so interested in the low level disk formatting
and so on. Which is a shame because I have that information!

Thanks in advance, and apologies if I am asking too much.

-Thomas





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