Christmas Carols on the IBM 704

To follow up on the post about the IBM 1401 musical suite by a Scandanavian composer, here’s an anecdote with a Holiday twist from retired IBMer John Van Gardner, an early pioneer in the kinds of computer music that inspired that suite! This excerpt is from file #17.


I had gotten interested in audio amplifiers when I built a high fidelity system in the navy.  During my school on the 704 as I learned how to program it I got an idea about how to use it as a square wave generator.  The 704 had four indicator lights on the console that could be turned on and off with program sense instructions.  They were used to give a visual indication of the progress of the program.  I keyed in a program using index instructions to turn sense light 1 on and off at different frequencies.  I connected the output of the sense light to the microphone input of the PA system.  The PA amplifier could not reproduce a square wave so the sound that came out sounded like a clean sign wave.


The IBM 704, introduced in 1954, was a large-scale computer designed for engineering and scientific calculations.

Some time later my daughter Joy received a toy xylophone with a songbook with simple one note songs like “Three Blind Mice” and some Christmas carols.  I took the book to work early one morning and connected the output of sense light 1 to the microphone input of the PA system.  I found the numbers to make the 704 play the musical scale.  Jack Bellinger came in later and heard it.  He showed it to Cal Jackson a Lockheed System Programmer and he modified the 704 assembly program to equate the scale note names to the numbers necessary to create that note.

A few weeks later in December 1957 we had a Christmas party in the programming area at Lockheed and Cal had made a tape that had all the Christmas carols from the little xylophone book on it.  It would play all the songs then rewind and start over….

I always wondered if I was the first person to play music with a digital computer.  I found the answer to that question when the internet came into being.  There were quit a few people that did it before me but at least I did it independently.


The December 2012 theme for The Greater IBM Connection is ‘corporate history’, and Paul Lasewicz, IBM Corporate Archivist, will be sharing with us some of the highlights from IBM’s history.

Paul Lasewicz, IBM Corporate Archivist

Paul Lasewicz, IBM Corporate Archivist



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