CHAPTER 23

Computer music

jack copeland and jason long

O

ne of Turing’s contributions to the digital age that has largely been overlooked is his

groundbreaking work on transforming the computer into a musical instrument.^1 It

is an urban myth of the music world that the first computer-generated musical notes

were heard in 1957, at the Bell Laboratories in the United States.^2 In fact, computer- generated

notes were heard in Turing’s Computing Machine Laboratory at Manchester University

about nine years previously. This chapter establishes Turing’s pioneering role in the history

of computer music. We also describe how Christopher Strachey, later Oxford University’s

first professor of computing, used and extended Turing’s note-playing subroutines so as to

create some of the earliest computer-generated melodies.

Introduction

A few weeks after Baby ran its first program (see Chapter 20) Turing accepted a job at Manchester

University. He improved on Baby’s bare-bones facilities, designing an input–output system

based on wartime cryptographic equipment (see Chapter 6). His tape reader, which used the

same teleprinter tape that ran through Colossus, converted the patterns of holes punched

across the tape into electrical pulses and fed these to the computer. The reader incorporated

a row of light-sensitive cells that read the holes in the moving tape—the same technology that

Colossus had used.

As the months passed, a large-scale computer took shape in the Manchester Computing

Machine Laboratory. Turing called it the ‘Manchester Electronic Computer Mark I’ (Fig. 23.1).^3

A broad division of labour developed that saw Kilburn and Williams working on the hard-

ware and Turing on the software. Williams concentrated his efforts on developing a new form

of supplementary memory, a rotating magnetic drum, while Kilburn took the leading role in

developing the other hardware. Turing designed the Mark I’s programming system, and went

on to write the world’s first programming manual.^4

The Mark I was operational in April 1949, although additional development continued as

the year progressed.^5 Ferranti, a Manchester engineering firm, contracted to build a marketable