Harmony Compiler was written by

Peter Samson Peter R. Samson (born 1941 in Fitchburg, Massachusetts) is an American computer scientist, best known for creating pioneering computer software for the TX-0 and PDP-1. Samson studied at the Massachusetts Institute of Technology (MIT) between 195 ...

at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

(MIT). The compiler was designed to encode music for the

PDP-1 The PDP-1 (''Programmed Data Processor-1'') is the first computer in Digital Equipment Corporation's PDP series and was first produced in 1959. It is famous for being the computer most important in the creation of hacker culture at Massachusett ...

and built on an earlier program Samson wrote for the

TX-0 The TX-0, for ''Transistorized Experimental computer zero'', but affectionately referred to as tixo (pronounced "tix oh"), was an early fully transistorized computer and contained a then-huge 64 K of 18-bit words of magnetic-core memory. Constru ...

computer. ]

Jack Dennis Jack Bonnell Dennis (born October 13, 1931) is a computer scientist and Emeritus Professor of Computer Science and Engineering at Massachusetts Institute of Technology. The work of Dennis in computer systems and computer languages is recogniz ...

noticed and had mentioned to Samson that the sound ''on'' or ''off'' state of the

's speaker could be enough to play music.
p. 24
/ref> They succeeded in building a

WYSIWYG In computing, WYSIWYG ( ), an acronym for What You See Is What You Get, is a system in which editing software allows content to be edited in a form that resembles its appearance when printed or displayed as a finished product, such as a printed d ...

program for one voice before or by 1960. For the PDP-1 which arrived at MIT in September 1961, Samson designed the Harmony Compiler which synthesizes four voices from input in a text-based notation. Although it created music in many genres, it was optimized for baroque music. PDP-1 music is merged from four channels and played back in stereo. Notes are on pitch and each has an undertone. The music does not stop for errors. Mistakes are greeted with a message from the typewriter's red ribbon, "To err is human, to forgive divine."p. 13
/ref> Samson joined the PDP-1 restoration project at the Computer History Museum in 2004 to recreate the music player.

References

* * Samson's description begins at 1:20.

Notes

Audio programming languages History of software {{music-software-stub