Item Description

[Aiken, Howard H][Hopper, Grace][IBM][Harvard Mark I]

A thick large book with fullpage black and white photographs of the Harvard Mark I electromechanical computer. A manual of operation for the Automatic Sequence Controlled Calculator, by the staff of the Computation Laboratory. with an Index, an extensive bibliography of related books & journal articles, and a historical introduction co-written by Aiken & Hopper.

The Harvard Mark I was the first programmable calculating machine, and the majority of this volume is devoted to technical descriptions of its components, architecture and operation, and coding examples (some of the earliest examples anywhere of digital computer programs (see Ceruzzi, 1985). This is Volume 1 of the Annals of the Computation Laboratory of Harvard University.

'In May 1944 the staff of the Computation Project began operations with the Automatic Sequence Controlled Calculator as an activity of the Bureau of Ships. One of the first tasks undertaken was the preparation of a report setting forth the coding procedures of the calculator. This was followed by detailed plugging instructions, which unfortunately were hardly completed before the code book was out of date. In the succeeding months, computing techniques were developed so rapidly that stabilized operating instructions could not be prepared. At the same time, many mathematicians, physicists & engineers requested copies of such data on operating techniques as were available in the laboratory.

This general and widespread interest encouraged the Staff to publish this Manual of Operation as the first volume of the Annals of the Computation Laboratory, rather than as a mimeographed compilation of notes as originally intended. Thus the Manual is unusual in that it is an outgrowth of notes prepared by the Staff primarily for their own use....

The Manual is also exceptional in that it represents the work of a great many people whose efforts have been closely integrated as is necessary in the operation of large-scale calculating machines. Chapters I & II represent extensions and revisions by Lt. Grace Murray Hopper, USNR, of the writer's old notes, many of which were written before work on the calculator was begun. Chapter III was written by Lieutenant Hopper with the collaboration of other members of the Staff. Chapters IV and V represent the outgrowth of the original code book and plugging instructions prepared by the writer and Lt(jg) Robert V D Campbell, USNR. Nearly every member of the Staff has made contributions to these chapters but Lt(jg) Richard M Block, USNR, especially should be mentioned. Chapter VI is made up of the solutions of elementary examples... largely the work of Lt(jg) Brooks J Lockhart, USNR....' (from the Preface by Howard Aiken)

CONTENTS -- Historical Introduction (sets the Mark I in its historical context and is an excellent overview of the history of computing to that time); Description of the Calculator; Electrical Circuits; Coding; Plugging Instructions; Solution of Examples; Bibliography;

Introduction to the Appendices (preparation of the appendices was mostly the work of Hopper with assistance of other Staff) -- Sequence Codes; Sequence Circuits; Register Circuits; Multiply Unit Circuits; Divide Unit Circuits; Relay List; Cam List; Fuse List; Index.

Plates include -- Calculating wheels designed by Charles Babbage; Front View of the Calculator; rear view of the Storage Counter unit and the Multiply-Divide Relay panel; Sequence Control Mechanism; Tape Racks; Switches; Storage Counters; Relays; Sequence control Mechanisms and Interpolators; Typewriters, Card feeds and Card Punch; Tape Punch; Relays and Cam; more.

'In 1937, the calculator was visualized as a switchboard on which are mounted various pieces of calculating machine apparatus. Each panel of the switchboard is given over to definite mathematical operations. It stands today much as originally imagined, in a stainless steel and glass case, fifty-one feet long and eight feet high. Two panels, each six feet long, extend at right angles from the back of the machine. Between these two panels is the four horsepower motor which drives the mechanical parts. Altogether the machine weighs about five tons....' (p. 11)

Most of the Manual describes the Mark I"s components and its architecture; it covers much of the actual coding for using the electromechanical computer to solve typical problems. Paul Ceruzzi writes that it contains 'the first extended analysis of what is now known as computer programming since Charles Babbage's and Lady Lovelace's writings a century earlier. The instruction sequences, which one finds scattered throughout this volume, are thus among the earliest examples anywhere of digital computer programs' (Ceruzzi 1985).