Date   : Tue, 20 Jul 2004 00:05:08 +0000
From   : "W.Scholten" <whs@...>
Subject: Re: bbcim/bbctape

Greg Cook wrote:

> Of course, when one's existing code wasn't designed with half bits in
> mind, retrofitting can get very messy indeed...

No, the retro fitting wasn't the problem (did that a year or so ago, and
wasn't much work). It's just a mess to keep track of where this happens
etc, and it makes standard tape images inaccurate or compressed
(depending on one's point of view). I don't see why Acorn did this.
Random single 2400Hz cycles in inter-block gaps I'd say one can just
forget (my view, see below). But systematic? Note that the Atom uses
direct port reading and the only format that can really handle anything
that an Atom can produce and read is direct wave specification (duration
of top/bottom sections).

For the BBC, if the extra 1/2 bit cannot be detected reliably (for
protection), then it still wouldn't be really useful to add 1/2 bit
support in the tape format (I think). I'm inclined to only want to
represent really useful stuff. Maybe more on this some other time.



> notice that the inter-block gaps vary by one cycle in length during a
> standard recording.

I noticed in 2001 when making bitstreams. This caused the decoding
problems I had... (see BBC ML message: Thu, 03 May 2001 08:10:57 +0000)



> Me three.  Only one response to the Web site in 18 months

I did refer a university teacher to your website for the user guide pdf
(actually, upon checking my email archive I saw I referred him directly
to the pdf file), he was happy with it, so unless that reponse was the
same guy, you've got at least two responses :)

Yes, that meant a BBC micro was used in a university level IT class in
2003! ;-)


Wouter
--
BBC/Atom/magazine scans:
     http://8-bit.summerfield-technology.co.uk/