Harmony Compiler was written by Peter Samson at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

(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 known for being the most important computer in the creation of hacker culture at the Massachusetts ...

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 64Kilo-, K of 18-bit words of magnetic-core memory. C ...

computer. ] Jack Dennis 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, refers to software that allows content to be edited in a form that resembles its appearance when printed or displayed as a finished product, such as a printed document, web ...

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 The Computer History Museum (CHM) is a computer museum in Mountain View, California. The museum presents stories and artifacts of Silicon Valley and the Information Age, and explores the Digital Revolution, computing revolution and its impact ...

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