View Full Version : My Video of Altair 8800b playing Music

May 6th, 2009, 07:44 PM
On page 6 and 7 of the Feb 1976 Dr. Dobb's Journal there is an article about using the Altair 8800 to make music by sending radio signals to a nearby AM radio. The article provides a program listing in octal, and the data for Fool on the Hill by the Beatles and Daisy (2001 Space Odyssey, etc.). To load the program just toggle in the program and data into the addresses suggested.

Would it work on an Altair 8800b ??? One way to find out.

Here is my rendition of Steve Dompier's program for playing music on an Altair.

Erik Klein also has a video of the same program on the Digibarn web site running on the original Altair 8800.

Here is the program listing:
http://vintagecomputer.net/cisc367/dr%20dobbs%20feb%201976%20Music%20With%20Altair.pd f

May 7th, 2009, 12:12 AM
Awesome, I guess you have seen the videos with PDP-8's doing the same:


May 7th, 2009, 02:57 AM
Wow, that's sweet.

At the Trenton Computer Festival in 2005 I saw a PDP 8 in person running a similar demo. I wonder if I can get a PDP 11 series to make music too. Next I think I will try it on an Altair 680.

May 7th, 2009, 08:34 AM
heh.. watched it and forwarded it both last night/this morning. So just out of curiosity, since I've heard of that demo before but was actually trying to think how it's working.

I'm assuming that's creating EMI at a specific rate to interfere with the radio at that frequency? What part specifically is making the noise and how is the programming controlling the pitch created?

- John

May 7th, 2009, 08:41 AM
I posted a link to the article that explains how it works in my earlier post. That should answer your questions. See my first post.

May 7th, 2009, 09:39 AM
lol, rtfm eh? ;-) Ok, so he comments the radio is picking up the "switching". I was thinking it would have been the EMI from the led's but I would think that would be higher pitch the more lights that are on and the notes don't seem to follow that pattern. The higher the number in memory the lower the pitch. Certainly interesting.

Very cool to see though, like I said, read about that and the homebrew club so neat to see it and read it first (well telecommuted) hand.

Terry Yager
May 7th, 2009, 12:49 PM
Beautiful, simply beautiful. You might consider posting the code in the comments section too, just in case someone wants to try it at home.