[Dorset] Evolution Alarm
Hi all, My Evolution alarm notification has stopped working if the computer is not switched on at the time set for the alarm to go off. It used to go off when I booted up. I think the problem started at about the time I upgraded to Ubuntu 10.04. Can anyone help please? Cheers, Peter. -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
[Dorset] Decoding Superboard II Cassettes.
Hi, There's another installment from Dave Beazley on his Superboard II. This time he's decoding an audio recording from it into bytes. (Some of the Python may be a bit harder to follow than before.) Decoding Superboard II Cassette Audio Using Python 3, Two Generators, and a Deque http://dabeaz.blogspot.com/2010/08/decoding-superboard-ii-cassette-audio.html He uses a deque as a sliding window over the audio samples, maintaining a count of the number of zero-crossings in the deque. Given that the `silence' before the data starts is the high frequency of a 1 and the start-bit is a lower-frequency 0, when that ZC count drops low enough, he knows the start bit sits squarely in the deque. He can then chomp through the following audio samples a bit's worth at a time until the whole byte and two stop-bits are consumed before returning to the sliding window search. http://en.wikipedia.org/wiki/Deque http://en.wikipedia.org/wiki/Zero-crossing He provides code and WAV to download and run. Here's the output with cat(1) showing up the CR, NUL, ..., LF that the SII outputs as a delay for when it has to read and process the data later. $ python3 kcs_decode.py osi_sample.wav | cat -A ^...@^@^...@^@^...@^@^...@^@^...@^@$ ^...@^@^...@^@^...@^@^...@^@^...@^@$ 10 FOR I = 1 TO 1000...@^@^...@^@^...@^@^...@^@^...@^@$ 20 PRINT I;^...@^@^...@^@^...@^@^...@^@^...@^@$ 30 NEXT i...@^@^...@^@^...@^@^...@^@^...@^@$ 40 end...@^@^...@^@^...@^@^...@^@^...@^@$ ok...@^@^...@^@^...@^@^...@^@^...@^@$ $ I expect the next installment will be to translate a subset of Python bytecode to 6502. :-) Cheers, Ralph. -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
Re: [Dorset] Decoding Superboard II Cassettes.
Archiving this. It's gold. On Mon, 2010-08-30 at 12:00 +0100, Ralph Corderoy wrote: Hi, There's another installment from Dave Beazley on his Superboard II. This time he's decoding an audio recording from it into bytes. (Some of the Python may be a bit harder to follow than before.) Decoding Superboard II Cassette Audio Using Python 3, Two Generators, and a Deque http://dabeaz.blogspot.com/2010/08/decoding-superboard-ii-cassette-audio.html He uses a deque as a sliding window over the audio samples, maintaining a count of the number of zero-crossings in the deque. Given that the `silence' before the data starts is the high frequency of a 1 and the start-bit is a lower-frequency 0, when that ZC count drops low enough, he knows the start bit sits squarely in the deque. He can then chomp through the following audio samples a bit's worth at a time until the whole byte and two stop-bits are consumed before returning to the sliding window search. http://en.wikipedia.org/wiki/Deque http://en.wikipedia.org/wiki/Zero-crossing He provides code and WAV to download and run. Here's the output with cat(1) showing up the CR, NUL, ..., LF that the SII outputs as a delay for when it has to read and process the data later. $ python3 kcs_decode.py osi_sample.wav | cat -A ^...@^@^...@^@^...@^@^...@^@^...@^@$ ^...@^@^...@^@^...@^@^...@^@^...@^@$ 10 FOR I = 1 TO 1000...@^@^...@^@^...@^@^...@^@^...@^@$ 20 PRINT I;^...@^@^...@^@^...@^@^...@^@^...@^@$ 30 NEXT i...@^@^...@^@^...@^@^...@^@^...@^@$ 40 end...@^@^...@^@^...@^@^...@^@^...@^@$ ok...@^@^...@^@^...@^@^...@^@^...@^@$ $ I expect the next installment will be to translate a subset of Python bytecode to 6502. :-) Cheers, Ralph. -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
Re: [Dorset] Audio Cassettes.
On Saturday 28 August 2010, Ralph Corderoy wrote: Hi Andy, I still have my old bbc micro and its digital (audio more like it!) casette recorder. using this python script I could do my backups to the cassette recorder - neat! Nice idea. I think they do C120s now for even more storage. And you could use one of those new tape-to-tape decks to produce the offsite copy. :-) That reminds me, I was going to see if my printer can handle vellum. http://www.ollydbg.de/Paperbak/ All I need is another python script to read the data back (and a few years!)- any offers of a read script? :) I think Dave mentions in one of the comments that it's coming along nicely. If he does another article on that I'll let the list know. Cheers, Ralph. -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 http://dorset.lug.org.uk/ -- Meets, Mailing list, IRC, LinkedIn, ... How to Report Bugs Effectively: http://bit.ly/4sACa Hi Ralph, Thanks for the link. This is really thought provoking. I can immediately think of lots of 3MB digital files (ascii text files containing personal items) that I would really like to save in a technology independent way - suitable for filing away in paper form - yet computer readable. (and it would survive an EMP! can be sent as simple snail-mail) Intriguing - I am experimenting with Paperback. You are a gold-mine! Regards Andy -- Andy Paterson -- Next meeting: Blandford Forum, Tuesday 2010-09-07 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ How to Report Bugs Effectively: http://bit.ly/4sACa
