1 7 ARABIC 1620: AN ANALYSIS AND PROCEDURE FOR COMPOSING COMPUTER MUSIC THESIS Presented to the Graduate Council of the North Texas State University in Partial Fulfillment of the Requirements For the Degree of MASTER OF MUSIC By William Loyd Lott, B. M. Denton, Texas August, 1968 TABLE OF CONTENTS Page LIST OF TABLES. .. 0 . 0 0 .P LIST OF ILLUSTRATIONS . 0 . V Chapter I. INTRODUCTION . * . 0 . 0 0 ."1 II. COMPUTER INPUT SPECIFICATIONS. 0 . 0 0 0 4 Tempo Blank: H-Code Note Rest Period III. REALIZATION PROCEDURES . * . 16 The Composition Process The Codification Process The Card Punch Process The Computer-Recording Process The Modification Process IV. ANALYSIS OF ARABICI1620. 26 APPENIX. 0 0 0 . 0 . .0 . 33 BIIBLIOGRAPHY. 0 0 . 0 . 0 . 0 . 0 40 iii LIST OF TA3LES Table Page I. Horizontal Interval Frequencies and Percentages . 32 iv LIST OF ILLUSTRATIONS Figure Page 1. Four-mColumn Field. 40 .... .... .5 2. Number of Notes, Rhythmic Notation, and Codes Equivalent to One Quarter Note Value..*. .10 3. Substitute Letters for Dotted Notes. ** 13 4. Substitute Letters for Sharp Notes . .. 13 5. Substitute Letters for Flat Notes. 14 6. Punching Positions of Digits, Letters, and the Special Character on the IBM Card . 19 7. Notation for Reverberation . 24 8. Notation for White Noise . 24 9. Oblique Modulated Signal Upward. 24 10. Oblique Modulated Signal Downward. 24 11. Modulated Signal in Contrary Motion. 24 12. Original Row and Theme. .26 13. Original Row in B Section.....*. .28 14. Design of a Mirrored Exponential Envelope. 28 15. Design Showing Rapid Alternation between Notes to Create Harmony . 29 16. The First Three Notes of Channel II in Diminution of Channel III . 30 17. Original Row Used As Ostinato. 30 V CHAPTER I INTRODUCTION Computers are used in the music field for generation of sound, for composing music, for analysis of music, and for musicological applications, such as cataloguing a bib liography of music literature. These areas are relatively new aspects of computer usage, and research is being con ducted to stay abreast of current technological advancements. Avant-grd composers are challenged by new advances in music. Computer-generated music is one of the new trends, but the composer is usually limited in the use of the medium for two reasons: there are no computers to which he may have access, and/or there is not enough knowl edge about computer-generated music. The composer sometimes feels that he must have vast knowledge of the computer be fore he can attempt to use it in musical composition; how ever, a limited amount of investigation of computer-generated music has shown that methods can be codified to the point where great technical knowledge is not required of the com poser. Arabic 1620 is designed for performance by the Inter national Business Machines 1620 Data Processing System, an electronic digital computer. The computer will generate the sounds, which are recorded onto magnetic tape. In order I 2 to generate sounds from the computer, information from the music is typed onto 80-column cards. The data from the cards are programmed through the computer, which stores this information. An AM radio receiver,1 placed on the computer console, will pick up the electromagnetic radiation emitted by the computer as it executes the program and will transmit through its loudspeaker the musical material that was punched on the IBM input cards. The Richard F. Smiley music program uses an approximation to the equal-tempered chromatic scale, American Standard Pitch, in which A4 (above middle C on the piano keyboard) equals 440 cycles per second. The computer is used for the generation of the pitches and the durations. Electronic analog equipment should then be used to add dynamics, reverberation, modulation, and filtering, which as of this time, the 1620 computer is un able to perform under the Smiley program. There are a number of musicians pursuing new musical advancements using computers. Important work in various fields of computer music is being done by the following people: Lejaren A. Hiller, Leonard M. Isaacson, and 1 The radio serves as a monitor so the programmer can hear the musical results. 2 Riehard F. Smiley, "Music Interpreter," abstracted from IBM Systems Reference Library, Catalog of Program for IBM 1620 and 1710 Data Processin Sysems(Hawthorne, New York, 1967)7 p. 107. 3 Robert A. Baker at the University of Illinois; M. V. Mathews and J. L. Divilbiss at the Bell Telephone Laboratories, hurray Hill, New Jersey; James C. Tenny, formerly at Bell Telephone Laboratories and currently at Polytechnic Insti tute of Brooklyn, New York; Arthur Roberts at the Argonne National Laboratory, Argonne, Illinois; Godfrey Winham and Hubert S. Howe at Princeton University; and Yannis Xenakis at Paris, France. This is by no means an exhaustive list, but these are probably the most prominent in the field. 3 Most of the researchers listed above use large, high speed computers. At present, most composers do not have access to these large computer systems. A more practical approach for generating music is to seek a small computer, which should be more commonly available to composers. Such an instrument is the IBI 1620 computer. A primary objective in this study is to gain maximum use of the small computer. 3Compositions-by these specialists include Illiac Suite for Stri Qartet, by Hiller and Isaacson, using an Illiac computer, Copter Cantata, by Hiller and Baker, using an IBt 7090 and CSX-l electronic digital computers, Music 4, by Mathews, Four Stochastic Studies and Ergodos I, by Tenny, MusicT7 Orpheus, and Maestro, by Roberts, using an ASI-210 computer, Music 4B, by Winham and Howe, us ing an IBM 7094, S481 2, Amorsima-Morsima, and Atrees, by Xenakis, using an IBM 7090. CHAPTER II COLIPUTER INPUT SPECIFICATIONS The object deck, which consists of cards representing the Smiley computer program, is processed into the memory of the IBM 1620 computer. Following this deck is the input data, which are the actual realization of the musical score. This chapter covers the preparation of the input data, IBM 80-column cards serve as the means for transmitting the information from the musical score into computer storage and language. Each card is divided into segments called fields. For the purpose of generating computer music in this study, four columns consist, of a field, with each card divided into twenty four-column fields. The first column of a field (the left column) is referred to as the octave column; the second as the note column; the third and fourth as the length columns. A field is a column or columns reserved for the punching of data of a specific nature. The field may consist of from one to eighty columns, depending upon the length of the particular type of information, 4 5 0 L L cN e e t o nn a t g g V e t t e h h X X X X Fig. 1--Four-column field The contents of a field may be any one of six classes: tempo, blank, H-code, note, rest, or period. The various classes of fields are distinguished by the interpreter (computer program) on the basis of the contents of the note column (except for tempo fields, about which the interpreter knows in advance). Tempo The interpreter requires a tempo for each tune or set of data. This is a six-digit decimal fraction equal to one-fortieth the length of a whole note, in seconds. Nor mally this tempo comes from a tempo field on the input cards. However, if the tempo field on the cards is blank, the programmer must type the tempo with the IBM typewriter.2 The four digits of a tempo field, whether they are already on the input cards or need to be typed, become the four high order digits of the tempo. The low-order digits are filled in as zeros automatically by the interpreter. 2 See the footnote under the Detailed Operating Pro cedure for the IBM 1620 Computer in the Appendix. 6 The first field on the first card of a set of data is interpreted as a tempo field. Should data in the note class be accidentally punched in the first field of the card, a blank IBM card may be inserted ahead of the first input data card. The tempo may then be typed. The digits, if typed in the tempo field, may range from 0000 to 9999, the former tempo being the COstest pos sible speed and the latter being the 1o*est. If the digits are typed by the IBM 1620 typewriter, as many as six digits can be specified. Blank If the field is not a tempo field, it is classified according to the contents of the note column. If this column is blank, the field is not processed. The inter preter immediately proceeds to the next field. This provision makes it possible to put one event or line of material on a card, leaving the rest of the fields blank. Material punched in this manner is easier to read (when it is being corrected) than material whose lines are run together on the card. If a few fields are used and the remainder of the card is blank, the interpreter goes to the next card without any delay. Should there be any blank fields between data on a card, the interpreter will 7 continue reading. It should be noted that the amount of blank space left on a card has no relevancy to the amount of time it takes for the interpreter to read it; nor does it have any bearing on the tempo or length of- the compo sition.