speak was a Unix utility that used a predefined set of rules to turn a file of English text into phoneme data compatible with a Federal Screw Works (later Votrax) model VS4 "Votrax" Speech Synthesizer.
As of late 2011, the original source code[4][5] for speak, and portions of speak.m (which is generated from speak.v)[6] were discovered.
[1] The speak utility was developed by Douglas McIlroy in the early 1970s at AT&T Bell Labs in Murray Hill, New Jersey.
[1] According to the McIlroy paper,[1] "K. Thompson and D. M. Ritchie integrated the device smoothly into the operating system", which is evident from /usr/sys/dev/vs.c "Screw Works Interface via DC-11".
The McIlroy Algorithm is a large set of rules, sub-rules, and sub-sub-rules, applied to a word to isolate long vowels, silent 'e's, and slowly convert each letter into its "Screw Works" equivalent phoneme code.