From: Stephen Crane Newsgroups: alt.folklore.computers Subject: Kansas City cassette recording format Date: 09 Dec 1997 11:50:08 +0000 Organization: Dept. of Computing, Imperial College, University of London, UK. Lines: 9 Message-ID: NNTP-Posting-Host: outoften.doc.ic.ac.uk X-Newsreader: Gnus v5.3/Emacs 19.34 Path: ccw.ch!aetna.dolphins.ch!news.planetc.com!news-xfer.siscom.net!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!nntp.news.xara.net!xara.net!server6.netnews.ja.net!server4.netnews.ja.net!doc.ic.ac.uk!not-for-mail Anyone out there got any technical information about this? I have some cassettes of varying age and quality whose information I'd like to retrieve, preferably using my PC's audio card. Ideally, someone will have written a program for Linux which does this but, given the info, I'll have a bash at it over Xmas. --Steve Stephen Crane, DoC, ICSTM, 180 Queen's Gate, London SW7 2BZ, UK "90% of everything is crap" -- Theodore Sturgeon. ###### From: ab528@FreeNet.Carleton.CA (Heinz W. Wiggeshoff) Newsgroups: alt.folklore.computers Subject: Re: Kansas City cassette recording format Date: 9 Dec 1997 19:00:30 GMT Organization: The National Capital FreeNet Lines: 53 Message-ID: <66k4ge$2ae@freenet-news.carleton.ca> References: Reply-To: ab528@FreeNet.Carleton.CA (Heinz W. Wiggeshoff) NNTP-Posting-Host: freenet5.carleton.ca X-Given-Sender: ab528@freenet5.carleton.ca (Heinz W. Wiggeshoff) Path: ccw.ch!aetna.dolphins.ch!news.planetc.com!atl-news-feed1.bbnplanet.com!cpk-news-hub1.bbnplanet.com!news.bbnplanet.com!howland.erols.net!torn!nott!cunews!freenet-news.carleton.ca!FreeNet.Carleton.CA!ab528 Stephen Crane (jsc@outoften.doc.ic.ac.uk) writes: > Anyone out there got any technical information about this? I have > some cassettes of varying age and quality whose information I'd like > to retrieve, preferably using my PC's audio card. Ideally, someone > will have written a program for Linux which does this but, given the > info, I'll have a bash at it over Xmas. From Microprocessor Interfacing Techniques by Austin Lesea and Rodnay Zaks (whatever happened to him?) c/r 1978 SYBEX Inc. ISBN 0-89588-003-2 p. 128 KANSAS CITY STANDARD In order to use these inexpensive recorders in the hobby market, a standard was proposed and adopted by hobbyists. Using frequency shift keying techniques, and frequency double frequency [sic] modem techniques, this standard is easy to use. The drawback is the data rate of 30 characters per second. The system takes standard serial RS-232C data ... and converts each bit to either 8 cycles of 2400 hertz (a "1") or 4 cycles of 1200 hertz (a "0"). To generate this, only a few flip-flips [sic] are required along with a quad NAND gate. Shown in Fig. 4-55 is the modulator. [Image sent on request] [Circuit function, ditto] The demodulator must detect whether 1200 hertz or 2400 hertz tones are present. There are many ways of doing this; however a common one is to detect zero crossings of the input signal. This will generate either 2400 or 4800 pulses per second. [Circuit details sent on request] The circuit for the demodulator appears in Fig. 4-56. The de- modulator timing appears in Fig. 4-57. Note how one gets back what one started with, along with the necessary clock information. If the tape speed varies, the data may still be recovered as the clock information will insure the UART receives the proper timing signal. No special software is needed as this interface makes the cassette look like a paper-tape, punch-reader combination to the computer. [Images sent on request] (This format is found between the KIM cassette interface, and the One Chip Digital Cassette controller using the NEC UPD371D.) (Surprisingly, the documentation for my Heathkit ETA-3400 only mentions the frequencies, not the details of the encoding.) ###### From: "George Gray" Newsgroups: alt.folklore.computers Subject: Re: Kansas City cassette recording format Date: Sun, 14 Dec 1997 23:45:10 -0500 Organization: Bell Atlantic Internet Solutions Lines: 27 Message-ID: <672csd$1p5@world1.bawave.com> References: NNTP-Posting-Host: 20934059.bellatlantic.net X-Newsreader: Microsoft Outlook Express 4.71.1712.3 X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 Path: ccw.ch!aetna.dolphins.ch!news.planetc.com!leto.ou.edu!news.ecn.uoknor.edu!news.eng.convex.com!cs.utexas.edu!howland.erols.net!world1.bellatlantic.net!news Oh man! This was the tape format I used on a couple old machines. It was highly publicized in the mags at the time. I had most of them... Sorry, wish I still had those old mags... Here are some sources you may try: Radio - Electronics magazine (1975-78) Kilobaud Microcomputing (no longer published; 1977) Byte Magazine (1975-1977) Dr Dobbs Journal (I have them somewhere; they published specs and software) Unfortunately, I do not know if the above sources are still obtainable. If I can find the DDJ's, I can scan them at post a message so you can get them. Good luck. Stephen Crane wrote in message ... >Anyone out there got any technical information about this? I have >some cassettes of varying age and quality whose information I'd like >to retrieve, preferably using my PC's audio card. Ideally, someone >will have written a program for Linux which does this but, given the >info, I'll have a bash at it over Xmas. > >--Steve >Stephen Crane, DoC, ICSTM, 180 Queen's Gate, London SW7 2BZ, UK >"90% of everything is crap" -- Theodore Sturgeon.