APPROVED FOR PUBLIC RELEASE. CASE 06-1104. PROJECT WHIRLWIND SUMMARY REPORT NO. 29 FIRST QUARTER 1952 Submitted to the OFFICE OF NAVAL RESEARCH Under Contract N5ori60 Project NR 048-097 and the UNITED STATES AIR FORCE Under Contract AF19(l22)-458 DIGITAL COMPUTER LABORATORY MASSACHUSETTS INSTITUTE OF TECHNOLOGY Cambridge 39, Massachusetts APPROVED FOR PUBLIC RELEASE. CASE 06-1104. TABLE OF CONTENTS FOREWORD QUARTERLY REVIEW (AND ABSTRACT) SYSTEM ENGINEERING . 1 Storage Reliability and Checking . 2 Input-Output 3 Operational Control Center CIRCUITS AND COMPONENTS . 1 Vacuum Tubes . 2 Component Replacements in WWI . 3 Ferromagnetic and Ferroelectric Cores .4 Transistors , ELECTROSTATIC STORAGE . 1 Tube Program INPUT-OUTPUT . 1 Magnetic Tape . 2 Magnetic Drums MATHEMATICS, CODING, AND APPLICATIONS . 1 Problems Being Solved . 2 Subroutines Completed ACADEMIC PROGRAM IN AUTOMATIC COMPUTATION AND NUMERICAL ANALYSIS . 1 Automatic Computation and Numerical Analysis . 2 Seminars on Computing Machine Methods APPENDIX . 1 Reports and Publications . 2 Professional Society Papers . 3 Visitors e APPROVED FOR PUBLIC RELEASE. CASE 06-1104. 1. QUARTERLY REVIEW tion of the 16x16 ceramic array has been (AND ABSTRACT) operated, but much work remains to be done. FOREWORD A multi-position ferroelectric switch has been developed which can perform many of the During the firstquarter of 1952 the Whirl­ switching tasks required in an information- wind I computer used one bank of storage handling system. A magnetic-materials group tubes with a density of 32x32 (1024) spots. has been formed for the purpose of develop­ Project Whirlwind The original bank of 16 x 16 tubes was remov­ ing ferromagnetic and ferroelectric materi­ ed from operation. The recently installed als for use in computer circuits. Project Whirlwind at the Massachusetts Institute of Technology Digital parity check has increased the reliability of A system has been set up to keep a com­ Computer Laboratory is sponsored by the Office of Naval Research under the storage section and has facilitated the plete record of each transistor being used in ContractN5ori60and the United States AirForce under Contract AF19( 122)- location of faults. About 85% of the scheduled development work at the Laboratory in order 458. The objectives of the Project are the development of an electronic applications time was useful during this peri­ digital computer of large capacity and very high speed, and its application to study the effects of various parameters to problems in mathematics, science, engineering, simulation, andcontrol. od. affecting transi stnrs as computer components. At the present time Project resources are about equally divided between As integration and testing of its various A two-transistor flip-flop has operated e {])°P ration Qf the computer and improvement of its reliability ;(2) applica­ components approach completion, the com - reliably at prf's up to 1 megacycle, and a tions of the computer to engineering and scientific problems; (3) storage puter becomes available for increased use by promising transistor gate circuit has been research and development; and (4) design of additional terminal facilities. the applications group. Section 6 of this re­ designed. port describes a number of engineering and The 256-spot storage tubes-removed from scientific problems to which the computer is The Whirlwind Computers the system, all of which were operating sat­ being applied. This work is providing valu­ isfactorily, had been in service an average of The Whirlwind computer is of the high-speed electronic digital type, in able experience in the development of tech­ 1635 hours. Four of the tubes had been used which quantities are represented as discrete numbers, and complex prob­ niques for the use of large-scale digital com­ for more than 3000 hours. The 17 tubes lems are solved by the repeated use of fundamental arithmetic and logical puting machines and the training of people to now operating at a density of 1024 spots have (i.e., control or selection) operations. Computations are executed by frac­ operate them. In addition, useful solutions' been in service an average of 1000 hours. tional-microsecond pulses in electronic circuits, of which the principal are being obtained. ones are (1) the flip-flop, a circuit containing two vacuum tubes so connected Two factors that have caused some of the that one tube or the other is conducting, but not both; (2) the gate or coin­ Failures of vacuum tubes were at a new tubes to have narrow margins have been cidence circuit; (3) the electrostatic storage tube, which uses an electron low during this quarter. Research on the re­ eliminated, so that the yield of good tubes is beam for storing digits as positive or negative charges on a storage surface. liability of tubes has been at a low ebb during expected to improve over the 65% during this Whirlwind 1 (WWI) may be regarded as a prototype from which other this period because of the heavy demands for quarter. Research toward the improvement computers will be evolved. It is being used both for a study of circuit tech­ acceptance tests of production tubes required of electrostatic storage tubes continues. niques and for the study of digital computer applications and problems. for new input-output equipment. Other com­ Whirlwind I uses numbers of 16 binary digits (equivalent to about 5 The interim magnetic-tape input-output decimal digits). This length was selected tolimit the machine to a practical ponents, particularly the new glass-envelope system is in operation in the computer. Cir­ size, but it permits the computation of many simulation problems. Calcu­ crystals, also showed increased reliability. cuits for the final magnetic-tape system have lations requiring greater number length are handled by the use of multiple- The 16x16 metallic magnetic-memory all been designed, and some units have been length numbers . Rapid-access electrostatic storage initially had a capacity array has been running with read-write times constructed. of 4096 binary digits, sufficient for some actual problemsand for prelimin­ reduced to 8-16 microseconds. An 8x8 por­ ary investigations inmost fields of interest. This capacity is being gradual­ ly increased toward the design figure of 32,768 digits. Present speed of the computer is 20,000 single-address operations per second, equivalent to about 6000 multiplications per second. This speed is higher than general scientific computationdernands at the present state of the art, but is needed for control and simulation studies. Reports Quarterly reports are issued to maintain a supply of up-to-date infor­ mation of the status of the Project. Detailed information on technical aspects of the Whirlwind program maybe found in theR-,E-,and M-series reports and memorandums that are issued to cover the work as it pro­ gresses. Of these, the R-series are the most formal, the M-series the least. A list of the publications issued during the period covered by this Summary, together with instructions for obtaining copies of them,appears in the Appendix. — APPROVED FOR PUBLIC RELEASE. CASE 06-1104. u 2. SYSTEM ENGINEERING 2. SYSTEM ENGINEERING total storage available. Therefore Bank A was removed from operation. This reduced the required storage-tube maintenance time and made more computer time available for The computer has been operating during experimental studies of storage-tube opera­ this quarter with one bank of storage tubes tion. Tests made in an effort to determine using a density of 32x32 (1024) registers. optimum rewrite times resulted in a better The computer has shown a general reliability adjustment of the parameters involved in the of 85% useful application time during the rewrite operation. There is, however, still period. more experimental work which should be done to complete the study of this problem. 2. 1 STORAGE RELIABILITY AND Under certain operating conditions, evi­ CHECKING dence of a small deflection shift in the storage tubes was found. Special programs devised Electrostatic storage has been function­ for investigating this fault resulted in the ing with the parity-check system outlined in detection of a plate-current shift in the 715C Summary Report 26. The parity system has amplifier tubes in the electrostatic-storage the advantage that it stops the computer im­ deflection output panels. Individual tests on mediately when an error occurs in information these tubes revealed that current shift existed read from storage . Without the parity check, only in the older tubes. (See Section 4.12 for a program may continue to operate using false further details.) This deflection trouble was information and thus produce erroneous re­ cured by replacing the bad tubes. However, sults, or it may try to perform an unallowed a further deflection shift that was then un­ operation as a result of a previous error in covered was found to be caused by an ion stored information. space charge in the body of the storage tube. The parity check has been very valuable The holding-gun operating voltages were re­ for two major reasons: adjusted, and this second deflection shift re­ (1) The check has uncovered various duced to a low value. problems in electrostatic storage and has Recently constructed storage tubes have been a great aid in locating these faults. The large operating margins, which provide the fact that the computer is stopped immediate­ required high reliability of operation with ly by a parity-check alarm prevents subse­ substantially less maintenance. Daily auto­ quent operations from masking the failure matic marginal checking has been extended symptoms. to the storage section and has been quite valu­ Fig. 2-1. Servicing of electrostatic-storage section. (2) In the event of a failure of one of the able in keeping it in good operating condition. storage tubes, the parity digit column may Fig. 2-1 shows this section (right center) be used as a replacement for the failing digit being serviced; a small section of the arith­ 2.