Archived posting to the Leica Users Group, 2016/06/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Thanks Jim for the account of your PDP-8 encounter. You might be interested in how the four-part music was generated. Peter got permission to attach wires to four of the six sense lights and programmed the computer to turn on and off each light at the desired sound frequency. This gave a square wave (ugh) from each for the four wires. Then passing the resulting signals through an R-C circuit smoothed the square edges giving a musical quality. It all then went to a Heathkit amplifier. Of course, there was no control of dynamics. Herbert Kanner kanner at acm.org Question Authority and the authorities will question you. > On Jun 26, 2016, at 4:00 PM, Jim Nichols <jhnichols at lighttube.net> > wrote: > > Thanks for the memories, Herb. My first encounter with a mini-computer > was, I believe, a PDP-8, a descendant of your original. It arrived as a > part of the fuel control system for a turbine engine test, and, when the > test ended, our Plant Engineering "hackers" looked for other applications. > We started with the two critical pressure measurements needed for an > accurate Mach number calculation during operation of the 16ft. Transonic > Wind Tunnel. By using the ratio of static to total pressure and the > corrections determined during the wind tunnel calibration, the PDP-8 gave > us real-time Mach number, displayed on small B&W TV monitors in front of > the various operating personnel. Things really developed from that small > start. > > Jim Nichols > Tullahoma, TN USA > > On 6/26/2016 5:45 PM, Herbert Kanner wrote: >> My mail program went nuts last week. Twice I sent a rather long piece of >> mail describing the circumstances around a Gallery picture and each time >> the mail went into a black hole and the text had to be composed again. >> This time I'm being smarter and writing and saving it first in a word >> processor. >> >> OK. Don't remember what I last posted re health, but I was in the >> hospital for over a week with congestive heart failure. Made a rapid >> recovery as soon as I got home, and after a couple of weeks, returned to >> volunteer week at the Computer History Museum. >> >> As a consequence of the loss of the Babbage Difference Engine, I rejoined >> the group that gives twice monthly demonstrations of a working PDP1 >> computer (vintage 1960), the first ?mini-computer?, in fact, the >> manufacturer (Digital Equipment Corporation) coined the term. >> >> The PDP1 is about the size of three household refrigerators. It's turned >> on at the throw of one switch. It sold for $120,000. In the year it came >> out, the manufacturer donated one to MIT. One professor permitted >> ?hackers? access to it from midnight to morning. This was before >> ?hackers? became a pejorative term. One of those hackers was Peter >> Samson, who figured out how to make the machine play four-part music, and >> our demo inclueds the opening of a Bach fugue. The other, Steve Russell, >> largely wrote the code for the world's first video game, Space War, which >> later became an arcade game. >> >> When I arrived at the Museum a week ago Saturday, I found the PDP1 team >> in the cafeteria area enjoing a post-lunch bull session. I just had to >> take a picture. We were all wearing our uniform red shirts. Note the guy >> on the right; that's Steve Russell. >> >> http://gallery.leica-users.org/v/herbk1/L1000005_001.jpg.html >> <http://gallery.leica-users.org/v/herbk1/L1000005_001.jpg.html> >> >> Please look ?large?. >> >> >> >> Herbert Kanner >> kanner at acm.org >> >> Question Authority and the authorities will question you. >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information >> > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >