View source for Harmony Compiler

{{Infobox Software
| name = Harmony Compiler
| logo = 
| screenshot = PDP music manuscript screen.png
| screenshot alt = Part of a music manuscript
| screenshot size = 100px
| caption = Manuscript, [https://web.archive.org/web/20170706120125/ftp://publications.ai.mit.edu/ai-publications/pdf/AIM-107.pdf ''Music Compiler''] (PDF)
| author = [[Peter Samson]]
| developer = 
| released = 1960, 2006
| latest release version = 
| latest release date = 
| latest preview version = 
| latest preview date = 
| operating system = 
| platform = [[PDP-1]]
| language = 
| genre = [[Music]]
| license = 
| website = [http://www.computerhistory.org/pdp-1/ PDP-1 Restoration Project]
}}
'''Harmony Compiler''' was written by [[Peter Samson]] at the [[Massachusetts Institute of Technology]] (MIT). The compiler was designed to encode music for the [[PDP-1]] and built on an earlier program Samson wrote for the [[TX-0]] computer.

[[Image:TX-0 music text screen.png|left|thumbnail|80px|alt=screenshot of music on a TX-0|[http://www.bitsavers.org/bits/MIT/tx-0/music/_text/musicx_eng.txt TX-0 music]]]
[[Jack Dennis]] noticed and had mentioned to Samson that the sound ''on'' or ''off'' state of the [[TX-0]]'s speaker could be enough to play music.<ref name=Levy>{{gutenberg | no=729 | name=Hackers: Heroes of the Computer Revolution by Steven Levy |bullet=none}}. [http://www.gutenberg.org/catalog/world/readfile?pageno=24&fk_files=36095 p. 24]</ref> They succeeded in building a [[WYSIWYG]] program for one voice before or by 1960.<ref name=musicx_eng>{{cite web | title=MUSIC X |date=28 May 1960 | url=http://www.bitsavers.org/bits/MIT/tx-0/music/_text/musicx_eng.txt | accessdate=2006-07-05}}</ref>

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."<ref name=Pope>{{gutenberg|no=7409 | name=An Essay on Criticism ''by Alexander Pope'' |bullet=none}} [http://www.gutenberg.org/catalog/world/readfile?pageno=13&fk_files=21814 p. 13]</ref>

Samson joined the PDP-1 restoration project<ref name=Cheponis>{{cite journal | author=Cheponis, Mike | title=Restoring the DEC PDP-1 Computer | journal=Core | publisher=Computer History Museum |date=Spring 2006 | url=http://www.computerhistory.org/pdp-1/ | accessdate=2007-11-23}}</ref> at the [[Computer History Museum]] in 2004 to recreate the music player.

==References==
* {{cite web | author=Smith, Daniel P. B. | title=PDP-1 Music |year=1997 | url=http://www.dpbsmith.com/pdp1music/index.html | accessdate=2006-07-05}}
* {{cite video | people=Samson, Peter |date=2006 |  title=The Mouse That Roared: PDP-1 Celebration Event Lecture 05.15.06  |  url=http://video.google.com/videoplay?docid=4995476926708958999&q=computer+history+dec | publisher=Computer History Museum | accessdate=2006-07-05}} Samson's description begins at 1:20.

==Notes==
<references />

[[Category:Audio programming languages]]
[[Category:History of software]]

{{music-software-stub}}