On 25 Dec, 2006, at 10:28, cctalk-request at classiccmp.org wrote: There some are old recordings of my 2nd generation mainframe at : http://ict1301.co.uk/13010520.htm I also have a fuller set of 33 files in .aiff format which the files on the web site were derived from. These were recorded from audio cassette tapes which are about 30 years old but seem to sound the same as I remember them. The programs to make the music is on punched cards and the card reader is currently unreliable and I don't want to risk the card decks reading them in as I only have one set. The sound came from the built in speaker, which is pulsed once for every two conditional branch instructions. I used to write pen plotter drivers for the Macintosh and there were some plotters made by Watanabe (later renamed GrafTec) which were suitable for music. The x and y axes were driven by noisy stepper motors. The speed was programmable and when drawing a large circle you could hear the stepper motors make a rising and falling tone as the angle changed. That is, drawing a 45 degree line the two motors worked at the same speed, and when drawing a horizontal/vertical line only one motor would be working For angles in between the tone would vary depending on the angle. The slower cheaper plotters made a grating sound but the faster more expensive ones were very melodic, though I never got around to programming them to make music myself, I would not be surprised if somebody did. Roger Holmes