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REPOR TRES.UMES

ED 010 764 SE 000 015 THE COMPUTER IN PHYSICS INSTRUCTION, REPORT OF THE CONFERENCE ON USES OF THE COMPUTER IN UNDERGRADUATE PHYSICS INSTRUCTION (UNIVERSITY OF CALIFORNIA, IRVINE, NOVEMBER 4-6, 1966). COMMISSION ON COLLEGE PHYSICS, ANN ARBOR, MICH. PUB DATE 65 ERRS PRICE MF-$0.18 HC-0.88 97p.

DESCRIPTORS.' *COMPUTER ASSISTED INSTRUCTION, *PHYSICS, *COLLEGE SCIENCE, INSTRUCTION, LEARNING, CONFERENCES, IRVINE, ANN ARBOR

.-.. THE ROLE OF THE COMPUTER IN UNDERGRADUATE PHYSICS INSTRUCVION'tS PRESENTED. MAJOR TOPICS INCLUDED IN THE REPORT ARE CURRICULAR ADMINISTRATIVE PROBLEMS, PEDAGOGICAL TECHNIQUES, AND SYSTEMS AND EQUIPMENT. INFORMATION RELATED TO LINGUISTICS MODE COMPUTER SYSTEMS, REMOTE CONSOLE EQUIPMENT, LINGUISTICS MODE PHYSICS PROGRAMS, COMPUTATIONAL MODE PHYSICS PROGRAMS, AND COMPUTATIONAL MODE COMPUTER LANGUAGES ARE INCLUDED IN THE REPORT. SEVERAL EXISTING UNIVERSITY COMPUTER-ASSISTED LEARNING SYSTEMS AND PROGRAMS ARE DESCRIBED. (AG) I /

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f / 4 Published by Fie Coi-n/ is;ion College Physits COVER PHOTO: View of the Natural Sciences Buildingat the University of California, Irvine, which houses thePhysics Depart- ment and in which several of the Conferencemeetings took place. Photo by John M. Fowler. pr." r

U.S. DEPARTMENT OF HEALTH, EDUCATION& WELFARE OFFICE OF EDUCATION SEP 2 0 1966

THIS DOCUMENT HAS BEEN REPRODUCEDEXACTLY AS RECEIVED FROM THE PERSON OR ORGANIZATION ORIGINATINGIT POINTS OF VIEW OR OPINIONS

STATED DO NOT NECESSARILY REPRESENTOFFICIAL OFFICE OF EDUCATION POSITION OR POLICY.

the

computer

in

physics

instruction

Report of the Conferenceon the Uses of the Computer in Undergraduate PhysicsInstruction held November 4-6. 1965 at The University of California Irvine

Sponsored by The Commissionon College Physics :1 NOTFILMED PAGEBLANK- PREcEDING

contents

PREFACE V

ACKNOWLEDGMENTS IX

INTRODUCTION Roles of the Computerin UniversityInstruction 1

WORKING GROUP REPORTS Curricular-AdministrativeProblems 9 Pedagogical Techniques 15 Systems. antl"Equipment 19

APPENDICES A.Linguistic ModeComputer Systems 25 B. Remote ConsoleEquipment 29 C.Linguistic Mode PhysicsPrograms 45 D. Four University-BasedSystems 49 E.Computational Mode Physics Programs 51 F.University of California,Santa Barbara, Computer System (with sample program) 55 G. ComputationalMode Computer Languages 69 H. Glossary 71 I.List of Participants 75 J.Flow Diagram: "Weightlessness" by ArnoldAwns 79

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preface

Topical conferences in physics are usually called after major advances have been made. When the planning began for the Con- ference on the Uses of the Computer in Undergraduate Physics Instruction, however, there were no advances to consider. The com- puter had found use in a few physics classrooms, but in an obvious extension of its research role, as a computational tool which in- creased the range of problems accessible to student solution. There were, and are, however, problems other than those in physics which face the instructor. There is a national pattern of increasing student enrollment and decreasing faculty time which is particularly evident in the large introductory courses. And there is an increasing number of students who would benefit from more individualized assistance of a rather routine sort; students who, lacking this help, now pass out of further serious interest in physics. In the experimental CAP programs which exist elsewhere, and in the vision seen by computer pioneers, there is the promise of help with these larger problems. It was on this promise that the Conference was based. The idea for the conference grew from discussions between Alfred Bork and Kenneth Ford in the fall of 1964. Ford and Bork had both had an introduction to the educational possibilities of the computer. Ford, at Irvine, had been exposed to the enthusiasm of those who planned a major fusion of technology and instruction at this new university. Bork had gained considerable experience with satism=onown I Computer-Assisted Instruction (CAI) has become a common appellation. In this report, to emphasise our view that instsuctlen in ibis way will not be the single or even the dominant mode in physics and to underscore the PH-Instructional features of our suggestions, v.le are using the acronym CAL, Computer-Assisted Learning. This also serves to honor the host state for our conference.

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classroom and laboratoryuse of computer programs. Both felt the need to bring interested physicists together withcomputer pioneers. Leonard Jossem and the Commissionon College Physics en- tered the discussions in the spring of 1965 andby that summer several physicistswere putting together-the first, necessarily crude, teaching dialogues at Seattle.2 By the end of thaitsummer the Con- ference had a goal, a place,a time, and a list of invitees. The goal was ambitious:to prepare a comprehensive report a handbookwhich would be immediately useful to the physicist who was interested in the computer's instructionalpossibilities. It was to contain a discussion of the pedagogical tasks presently feasi- ble for the computer, to foresee the curricularadministrativeprob- lems its introduction would raise, andto catalog the available and pertinent equipment. As a place, Irvine wasa natural choice. It had installed its computer and student terminals almost before its students. Its dean, Ralph Gerard, isan enthusiastic herald of the computer's role in education, and Kenneth Ford is the chairmanof the physics department. The time, November 1965, seemed righttoo: It was after the first trials at Seattle; itwas a year before the expected delivery of the first big timesharingsystems and at least two years beforeany real possibilities of widespread classroomtesting. In fact, however, it was almost too late. Computer technologydevelops rapidly and report writing is slow. The list of inviteeswas easily drawn up. First, all of the physi- cists known to have dabbled in thisnew medium or expressed some desire to do so were invited. To this listwas added an approximately equal number of computer experts either caughtbetween confer- ences, resident on the West Coast, or just generous enoughto help the physicists out. We then let the computerrelatedindustries know of our plans and urged that they be represented. The Conference wasa working conference. Its structure was simple. The first daywas for input; the second day, assembly and writing; and the third, review. The speakersat the opening session were E. N. Adams,' who surveyed the role of the computer in in- struction; Joseph Rosenbaum,' who described fourexperimental instructional computerprograms; and Glen Culler,'" who previewed

Working Conference on New Instructional Materials held at the University of Washingtonduring the summer of 1965. *Director, ComputerAssisted Instruction, IBM Instructional Systems Development,Watson Research Center. 4 Education and Training Staff, System Development Corporation. " Director, Computer Center, University of California, Santa Barbara.

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an intriguingly simple remote terminal with enormous computa- tional possibilities. (This was demonstrated later in the Conference.) A slightly condensed version of Adams' talk serves to introduce this Report. Rosenbaum's remarks, in abstracted form, makeup Appendix D, and Culler's talk, together with a sample problem solved by his system, is given in Appendix F. The afternoon was given over to the industrial representatives who described the hardware and software now available, andgave us some glimpses of future lines of development. Three working groups were convened the second day. The reports of these groups and the appendices which they called for form the bulk of this Report. The group surveying curricular administrative problems was asked to be almost clairvoyant; it tried to foresee the operational development of the computer as a part of the instructional system in higher education. Their report will, we hope, help prepare the thoughtful physicist or administrator for the problems as well as the opportunities ahead. The group on pedagogy and the groupon systems and equip- ment had more narrow fields of study and a little more real material to examine. The pedagogy group had some guidelines from Seattle and the systems and equipment group had almosttoo many exam- ples of hardware and software to classify and describe. We have already come a long way from Irvine. Twoprogram- - writing activities will begin thissummerone at the MIT Science Teaching Center; one at Stony Brook. Students will, throughsev- eral remote terminals at Stony Brook, already have signedonto the Seattledeveloped geometrical optics unit (see Appendix C) this spring, providing the first largescale student experience with CAL in physics. It is our hope that this Report willserve usefully before its early obsolescence, that it will stimulate and assist further creative experimentation. Only by such experimentationcan the problems which we anticipate be solved and the promise.we foresee be re- alized.

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acknowledgments

Any conference report is a joint effort, but in the preparation of this report, the CCP staff has hadto rely even more than usual on outside assistance. The list of acknowledgments is thus a long one, longer for certain than the list of participants that it must include. We wish to make a special acknowledgmentto the working group chairmenDonald R. Brown, Edward D. Lambe, and Bur- ton D. Friedfor their help before, during and after the Confer- ence. Karl Zinn (The University of Michigan) contributed much of the material for the appendiceson equipment and existing CAL systems; his careful reading of the technical material and hissug- gestions have helped to make these sectionsaccurate and compre- hensive. We also express our appreciationto the following people who either contributed written materialto the report, provided neces- sary data, and/or read and commented on parts of the report: E. N. Adams (IBM Watson Research Center), Alfred M.Bork (Reed College), Ralph Caplan, Glen J. Culler (University of California, Santa Barbara), Joseph Rosenbaum (System Development Corpo- ration), Donald Shirer (Valparaiso University), Franklin H.Wester- velt (The University of Michigan), William F. Storey (Michigan Bell Telephone Company), andnumerous manufacturers' repre- sentatives who provided much of the information appearing in Appendix B. We extend our thanks to Kenneth Ford and the administration of the University of California at Irvine for their smoothhandling of local arrangements and pleasant performance of their dutiesas Conference host. The selection of material and the final writing of all sections was done by John M. Fowler, Peter G. Roll, and Barbara Z. Blue- stone of the CCP staff; we accept responsibility for whatever errors and/or omissions have occurred in the Report.

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introduction

Roles of the Computerin University Instruction'

Much creative spadework andmany detailed explor- administrative areas of impact of thecomputer on the atory developments will have to be made before the university program as theyappear to me. The first role full potential of thecomputer as an instructional tool of the computer is as a vehicle for thecomputer can be exploited. This development must proceed in science discipline.... two directions. One of these is the creation ofnew A second role is as a general university servicepro- technological tools with special value for educational viding remote computing facilities...to timeshare use; the other is the development ofan understanding the services of a large highspeed centralcomputer of how these tools are to be used. through a network of terminals. .around the One purpose of this Conference isto point to im- campus.... portant particular directions of such development A tbird role of great apparent future importanceis where these directionscan be recognized. Another is as an essential component of the generalized library to indicate which applications of thecomputer to function...of storage, processing, and distribution of physics instruction may bemost profitably pursued information.... with techniques thatare presently feasible. I believe A fourth role of the computer isas an active element that obtaining experience with theapplication of in the instructional process itself. This rolewe will stateoftheart technologymay be the more impor- refer to as computer assistance to instructionor CAI.2 tant undertaking of the two in the immediate future; It is a complex role, involving the exploitation ofsev- so little is yet established concerning the methodology eral major subroles which I will referto as "themes," of computer use in education thateven a moderate because, although distinct innature, several may be amount of instructional experienceseems capable of present concurrently in a particular application. The broadly affectingour perspective of what is needed remainder of this paper will be concerned witha sur- and whit will be important in thelonger range future. vey of these individual themes. In accordance with this belief theemphasis of my We will categorize the major themes in CAIas fol- remarks will be on whatseems feasible in the immedi- lows: (1) manmachine communication; (2) machine ate future for operational exploration inan instruc- administered recitation and drill; (3) the Ersatz lab- tional environment. 1 oratory; (4) recording and processing student perform- I might begin by indicating the fourmain non- ance; and (5) testing.

1The following is a slight condensation ofan invited speech delivered to the Conference by Dr. E. N. Adams, Director of Computer Assisted Instruction 2 As indicated in the preface, we have chosen touse the acronym CAL (Com- at IBM's Watson Research Center in Yorktown Heights.A complete transcript puterAssisted Learning) rather than CAI throughout this Report [editor's of this talk is available from Dr. Adams. note].

1 Man-Machine Communication is the recognition of an input messageas one of a group of prestored messages.'Such a processing capabil- The importance of the first of these themes arises ity may suffice for applications in which the from the serious difficulties which messages are intrinsic in man are always of a simple sort; for example, the selection machine communication, and the corresponoUng bene- of a single key of a keyboard or a single field ofa fits which may be realized by facilitating that communi- keyboard. For many instructional purposes it is desir- cation through superior station equipment andcom- able to have the machine accept relatively complex munications capability. Basic to the communication messages, particularly messages in naturallanguage. process are both the physical organs of communication In such applications more extensive logical processing with the computer and, with each of these, theim- capability is needed. Some kind of editing is plied or associated logical capabilities of necessary the comput- to cope with the vagaries of keying and punctuation. ing system. Some at' least rudimentary pattern recognition tech- One of the most common means of getting informa- niques may be desirable for estimating the similarity tion into and out of a computer is through the use of of nonidentical messages. Very desirable for physics punched cards Much of the early work in CAI instruction is some ability to manipulateor at least has been done using this offline, slowresponsecom- evaluate mathematical functions. munication means. As one goes beyond the requirement for exact match For a number of the potential instructionaluses of processing and progresses down the list from editing the computer it is essential that theuser be online; to formula manipulation, the complexity of program i.e., in direct and immediate communication with the preparation and the requirements for program storage machine in so-called "conversational mode." Com- increase significantly. Moreover, on a perterminal monlyused means for online communication of serviced basis, the execution of more complexpro- alphanumeric messages isan inputoutput typewriter, grams normally imposes a greater average load on the or a console consisting of a keyboard and a cathoderay processor. Very elaborate processing requirements can tube display. For inputmessages which are not simply prove excessively costly. Thus, it is prudent to try to alphanumerical, various kinds of special keyboardsor stipulate processing requirements on the basis ofa other switchtype selectors are feasible. Foroutput a realistic assessment of tradeoff of total student load great variety of terminal configurations are also feasi- serviced against complexity of pedagogical function. ble using lights, fluorescent panels,etc. In addition, Programming language and operational features of terminal configurations can readily be engineeredto the control program should be designed after careful incorporate display capabilities suchas randomly consideration of the intended modes of instructional accessed still pictures, audio recordings, moving film, use and the convenience of the putative users.... and video tape. In addition to equipment which communicates with Each piece of such terminal gear must havea suit- the computer by means of symbolic messages, there is able "interface unit"or "adapter" so that it can com- terminal equipment which processes analogue mes- municate with the computer in the appropriatema- sages. With such equipment it is technologically feasi- chine language. As software, thecomputer.must have ble to some significant extent to synthesize audio within its repertoire of operation codescommands messages, to display data in the form of graphs and which permit it to control andto receive information other synthesized video displays, to accept graphical from the terminal equipment.... or video input directly through electronic slates, light The utility of the system for instructionaluse is pens, optical scanners, or kinescopes, and similarly to dependent in an importantway on the capability of accept audio and other analogue data directly as ana- the computer to process linguistic information and also logue messages. . on the facility with which a system user (e.g., a physics Finally, I will comment on the oftendiscussed pos- teacher) can program the use of the processing capabil- sibilities of having computers directly translate voiced ity. The first of these importantmatters is a question sound or graphical input to alphanumeric messages of what particular functional routines foi 'message for subsequent processing. My judgment is that, al- processing are available in thecomputer system pro- though limited feasibility of such techniques has been gram; the second is a question of the procedures for demonstrated by various workers exploring thisap- operating.the system and of the programminglanguage plication, general use of such techniques asa principal in which the user formulates his instructions. and normal means of input is not yet close to practic- The most elementary messageprocessingoperation ability.

2 Machine Administered Recitation and Drill Ersatz laboratory I mean something. different;a lab- oratory without the usual kind of equipment, a kind A second major instructional theme of CAI involves Of "substitute" laboratory, similar inuse if not in the direct machine administration of recitation and substance to the traditional laboratory. Using CAI in drill. Here the thrust of effort is to presentprogram- such a laboratory mode, one may realize at leastsome med instructional sequences whichuse sophisticated of the value of wellconceived laboratory instruction. algorithms of presentation and of response processing in general: that of exercising, and hence developing made possible by the logical and calculational capabil- in the student, the facility to carry through relatively ities of the computer. The mode of operation is basic- complex tasks under his own initiative and with mini- ally one of individual student recitation, with the mal supervision, and in that way learning by manipu- student communicating in conversational mode with lating "reality" and observing the reactions. Ofcourse, the computing system and receiving tutorialcommen- CAI in an Ersatz laboratory cannot replacesome of tary from the computer, according to a generalpro- the important values of traditional instruction ina gram prepared by a tutorial programmer.... traditional laboratory, and would not be satisfactory Early "teaching machines" and programmedtexts as more than a partial substitute for such instruction. were characterized by relatively rigid, individually On the other hand the Ersatz laboratory has special simple tasks, which were, for the most part, unchal- advantages which may be understood by considering lenging and not very interesting. These characteristics some examples of its realization. One example is the are not intrinsic to programmed learning; they had instruction in management techniques by means ofa their origin in the limited technology of studentre- business game in which a player, or a team of players, sponse processing which had until recently been avail- operates an imaginary business in competition with able to the programmer. With acomputer to adminis- either a predetermined performance criterionor with ter a program of instruction, the programmermay other imaginary businesses operated by otherteams avoid much of this rigidity and dullness....Further, undergoing instruction. The players periodically make the computer may be programmedto arrange for decisions of the sort involved in operationalmanage- continual adjustment of item difficultyor item pacing ment; the results of their decisions are submitted to a so that the student works at a predetermined level of computer simulator; the computer simulates the run- interim and final achievement, avoiding extremes of ning of the hypothetical business environment fora either boredom or discouragement. period of time under the impact of these decisions; it Given the capability through the computerto re- reports back the business results at the end of the member a student's past experience, to edit and analyze period; and finally, the players study reports of operat- his response to a certain extent, and to take account of ing results and initiate another cycle....In this both present and past behavior in controllingprogram laboratory the computer performs no direct tutorial flow, a course programmer can now reasonably aspire service, but merely serves as an offline calculational to produce a program of instruction which has some- aid to quickly inform the students of the hypothetical thing of the quality of the interaction betweena stu- consequences of their hypothetical business decisions. dent and a human tutor. Instead of onlya smallstep A related example of such CAI laboratory instruc- task, he can present a complex, structured taskas a tion was encountered in a course in lens design for sequence of nontrivial contingent decisionsor actions, optical engineers. This course makes use ofa computer and he can work through it with the student ina service program which, to speak loosely, does repeated tutorial manner. Such a capability wouldseem to be ray tracing calculations and calculates values for vari- of relatively great importance in physics instruction, ous merit figures of a hypothetical optical system, which which does not seem suited to smallstep programming. is characterized to the computer program by theor- dinary parameters of optical design. To use the pro- The Ersatz Laboratory gram, the student lens designer chooses and enters the values of these parameters into the lens evaluationpro- The third theme of CAI I will call the "Ersatz gram; what he gets back are the computed quantities laboratory."...I am not referring here to the use of from which he can judge the quality of the resulting CAI in. association with laboratory equipment. It is system for its desired purpose. By repeated running clearly feasible to incorporate computerassisted in- of this program a student engineer may explore the struction into a traditional laboratory toa certain sensitivity of the performance of an opticalsystem of extent, possibly to a considerable extent....By 'an interest to the various parameters of design....

al& sk,71.7,

There is an advantage to the explicit presentation analysis of data obtained in conjunction with machine- of the Ersatz lab as a means of exposition of theoretical administered recitation and drill. Thus, if all of the models of reality: we can offer the students laboratory data from student performanceon the recitation and CAI programs which go quite far in the representation drill were accumulated and properly analyzedas the of the abstract. Clearly, a computerprogram can simu- input to a continuous examination, the data base for late processes operatingover ranges of time, size, tem- test analysis would be expanded enormously, and the perature, etc., which couldnever be realized in any potential diagnostic power of thetest increased corre- single laboratory or even inany real laboratory. By spondingly. One yield from such testing could be im- manipulating the parameters ofprograms simulating proved measures of student achievement;another, and these processes, a studentcan explore and get the possibly more important,one could be that of con- "feel" of the physics inareas of physical reality which tinuing student classification and placement,a continu- he must otherwise approachon a purely theoretical ous "tailoring" of the student's curriculum to his plane.... evidenced needs. Recording and Processing Student Performance State-of-the-ArtCAI Research A fourth theme of CAI involves the monitoring, The above survey should give a reasonable indica- recording, itemizing, summarizing and analyzingof tion of the potential scope of computer aidto instruc- student behavior for a variety ofpurposes. I will tion. Let me present nowsome personal thoughts as enumerate three major purposes. One is the compila- to why it is relatively important at this time to do tion and analysis of individual studentperformance research by means of "state-of-the-art" instruction data for tutorial, diagnostic, and remedialpurposes. A via CAI. I have been doingsome of this research for second is the analysis andsummary of statistical stu- several years, and have becomevery conscious of n dent performance data in accordance withcharacter- number of major practical difficulties. My remarks will istics of the course items themselves, withthe object be directed to some of these difficultieson the assump- of improving the instructional material.A third pur- tion that wherever thereare difficulties there are things pose is behavioral research, which may concern itself to be learned. with analyzing latencies of response, or a variety of ....In programming a CAI system, one must give physiological and/or environmental variables,in cor- appropriate thought to all those whoare going to use relation with performance of varioustasks.... it, which means not merely students, but alsosystem Testing operators, supervising teachers, supervising adminis- trators, curriculum specialists, and behavioral research The fifth and final theme ofmy categorization is people. What may appear to be operational niceties that of testing. There are severalways one may con- for an experimental system turn outto be necessities ceive of the computer as affecting the testingprocess. when it comes to instructional evaluation: authors and One is as a technicalmeans of achieving controlled especially students react strongly to "small" irritations presentation of standardizedtests. In addition to im- which anight a priori seem to be minor in comparison provement of test administration, thisuse of the com- with the "big" problems. It is especially importantto puter may be of special interest during the standardi- have programming languages and/or operationalpro- zation phase of test preparation, wherethe difficulty cedures which are really convenient for the various of getting good control of presentationconditions can users, which do not demand too much of them and reflect itself in an apparent vitiationof the test items yet do a good deal for them. themselves. Quite apart from the many detailed difficulties of A second potentiality is thevery open-ended one designing a usable system, there is the problem of of developing new test methods or testing techniques. learning what to do with it....In my judgment, this Tutored testing, sequential testing,tests which have problem area is presentlya crucial one in terms of items which depend on student profiles,tests., incor- accelerating the development of the field. Whereas it porating latencies and other physiological data-allof is commonly supposed thatany problem of pedagogy these become feasible in principle with thecompu- will be disposed of by findingways "to help the ter.... teachers talk to the engineers," I think the problem In another direction, an enlarged diagnosticpoten- is harder than that. Any extensiveuse of the computer tial from testing may be realized throughcomputer as an instructional tool in physics, for example, would

4 permitif not requirea substantial restructuring of lent to writing a textbook coveringa year's work. A the whole interlocking process of lectures, problem program must be thought through in much finer detail sessions, homework, quizzes, and laboratories, anda than a book, especially if the programming followsa reapportionment of the various educational objectives non-conventional pedagogy. among them. Perhaps the most essential step in de- Therefore a project to prepare a large experimental signing a good program is that of thinking through program requires... atthe present "invention stage," how one would intend to do this restructuring. ...subject-matter experts working on a full-time Unfortunately, however, the programmer does not "saturation" basis, unencumbered by other responsi- have any natural and well-defined frame of reference bilities and aided by substantial technical and clerical in which to rework the process: how theprocess is help. It is important to simplify andautomate the structured depends on what the machine is to do; programming job to whatever extent possible....A what it is to do depends on what itcan do; but what it set of user-specialized program routines...prepared can do is not fixed, nor is it immediately known to in the form of a "programming language,"can greatly the "teacher-turned-programmer." If he didn't design expedite translation of pedagogical ideas intoexecut- the systems program of the machine, it almostcer- able programs. It is also important to have efficient tainly will not have all of the capabilities he would means of reusing each programming technique on new wish in a form convenient for hisuse. Some extensions material with a minimal amount of reprogramming. of capability which he would desiremay be had, so to Generally speaking, this means that the programming speak, for the asking; on the other hand, others, which language and procedures should accommodate "high- to the technically-naive person might seem similar, level" as well as "low-level" statements. may actually be practically impossible to have.... Since for most practical purposes the only satisfactory Ideally,the pedagogical innovator should become measure of the pedagogical value of a program is to enough of an engineer to understand in its essentials see how well students learn from it, it seems important the work of those who are developing the machine that testing be done using real students ina fairly capacities which he needsto accomplish his peda- realistic educational situation. However, for each sub- gogical task. He can then adjust his specificationof the ject area and educational milieu thereare limitations pedagogical task to facilitate the engineeringwork on what kind of experimentation is permissible and, and the educational objective simultaneously. for given materials, what populations of studentsare Even where creative teachers and systems people available....Attention must also be given to a num- have been able to devise whatappear to be promising ber of potential' difficulties of scheduling and logis- techniques and strategies of teaching ina particular tics.... area,they must continuallytesttheir ideas on learners....Let us consider some of the difficulties Conclusion involved in creating experimentalprograms incor- The task of developing CAI is clearlya complex porating these techniques and strategies. one. In my judgment it must be predominantly an The most vexing problem here is the interaction of empirical task. I think that, despite the existence ofa technique and content ina program: experimental considerable body of knowledge with regardto human materials which are to be useful for evaluationexperi- learning and considerable expertise with regardto in- ments must not only embody the techniques and struction, the primary resource required will be the strategies to be studied, but must embodythem in intuition of creative teachers, curriculum specialists, materials of adequate intellectual and estheticquality. and technical workers.. A second problem is connected withprogram size. On I hope that this group will share my conviction of the one hand, it is very desirable thatan experimental the great importance of pedagogyas a topic, and ex- instructional program cover a large enough unit of perimental programmingas a vehicle, for early ex- commonly-understood contentso that student per- ploration. I also hope that, in its deliberations, the formance can be evaluated ina straight-forward way Conference will discover at leasta few tasks or projects with a minimum of redundant "control" experimen- of immediate feasibility which might have special tation. On the other hand, the quantity ofmere claims for Commission sponsorship, because I believe writing in an experimental programcan be very large that physicists as a group are particularly well quali- in proportion to the instruction achieved. Writinga fied by background and temperament to contribute one-year program in any subject is not merely equiva- to developments of the sort needed.

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El t workinggroup

.4 1, ri4. ' 4 , ,ePA'4..,40' ''. -1111 °IL , reports

Curricular-Administrative Problems

Pedagogical Techniques

Systems and Equipment r Curricular-Administrative PRECED.ING PAGE BUM-NO.1E0AM

Problems'

Our group report considers broadly the operational course, so that it is difficult to make general statements development of the computeras an instructional aid applicable to all course varieties in physics; neverthe- from the viewpoints of three parts of the educational less, it is within this basic structure that thecomputer system: the teacher, the student, and the administrator. must make its contribution. It is therefore necessary From each viewpoint, in spite of the absence of actual to evaluate its capabilities against the requirements of experience, we have suggestedsome guidelines for such a system. future CAL experimentation. The computer will be least importantas an element in the presentational mode. The student terminal and The Teacher the associated computer system is too expensive for the Initiative in the educational system belongsto the student to use like a book. The lecture,text, and the teacher. Within this system both the student body and other elements under the heading of presentationcan the administration producesome constraints, but the therefore be expected to continue to dominate this teacher retains a. considerable amount of flexibility. mode. Through his choice of lectures, the assignments he It is possible that in some instructional formats the makes, his laboratory design, and the audio and visual computer will play an important part in choosing aids he uses, he controls the presentation of material. and ordering materials for presentation. Inan instruc- He sets the pace for the student and determines the tion session with a student, centered, for example,on format within which the studentmust respond. a broadlybased review problem, the computer could Furthermore, he evaluates studentresponse to these be programmed to refer toa video tape section of a presentations and can alter thepace or the format as previous lecture or to a short demonstration film,or he sees fit. The CurricularAdministrativeWorking to refer to textual material. Such a program would Group considered how the computer mightaugment, make possible a presentation directed to the needs of the indiVidual student. and even alter, the course structure and theteacher's personal contributions within thatstructure. The use of the computer in its computational model The elements from which an instructor designs his could also be classified as presentational (see the Re- course can be classified under three main headings: port on Pedagogical Techniques and Appendix F). presentation, student response processing, and feed- With the expanded computational capacity ofa com- back. A list of the common course elements under these puter the student can be served more realistic problems as examples of the application of physics. headings is given in Table 1 (p. 00).Emphasis on one or another of these elements varies from course to 2 We distinguish in this report two instructional uses of the computer: the linguistic mode, in which the computer bases its presentation on the student's I Edward D. Lambe, Chairman; E. N. Adams, Kenneth Ford, W. Thomas response; and the computational mode, in which the computer is used as a Joyner, James Kearns, Joseph Rosenbaum, Edward Turner. computing or data processing device.

9

AIL ELEMENTS OF PHYSICS TEACHING Table I 4 phasisA. of presentation.The It commonly instructor consists controlsPresentational of: the method and em- responsesdentsIL Student is based required Res:ponse on of the Thethe Processingformal students. success and or informalfailure of the individual sus- enoughrelatedC. Feedback to activities influence of Studenteitherthe subsequent the response instructor course- which or the comes in quickly 2. 1.Live Reading: Lectures: textbook, possibly or turesupplemented supplementaryassignments. demonstrations by lec- or films. 1. Examination: formalhis response,the understanding student calling to demonstrate, of for the material at specific presented. times, backundersuccessstudent some "Student of can the information, proridc course. Response Allinformation for courseProcessing" example: elements about can listed feed the 3. Films, TV, or Audio: thesetopic.lectures, can or be segments- entire dealing with a specific 3.2. HomeworkRecitation classes:Problems: the graded studentprovideintervals. carefollyt, responds achievement these ver- information at regular 1. Examinations: informationusuallyinally the obtained too presentation not late made tois affectusu- until by the thethe student instructornext and time changes theare 4. Direct Experience: the student'ssupplementedportant,experience accumulated though with by uneven, hissome environment of resource. the following: Itis mayan im- be 4. Laboratory: experiments rialstratesballybased presented to onthe the the state presented mate- in of lecture his comprehension.material or text. and demon- 2. Homework Assignments:student,forcourse most the theusefulisinstructor given. unanalyzed to the to use results as feedback. are difficult d. c.h.a.Take-homt CorridorLaboratoryLecture demonstrations demonstrations experiments, experiments toys, etc. 3. Recitation: if this were handledanismworth.director, byis However, not thethe verycourse feedback effective. the usual would indirect be of mech- great e. Specially designed roomschangeexperiencescertain to demonstrate in set scale, of (various uncommon etc.). a aspects but ofimportant motion, 4. Other mechanisms such asinformal timesquestionnaires used group to advantage.discussions, or etc., are some- owNINNIest At the present stage of development, computer tech- the grade judgment will be made. Hemay then be nology will probably make its greatest contribution in able to leave it to the student to utilize theresources the second and third categories of Table 1. In particu- made available to himlectures insome cases, textual lar, the computer offers the possibility of onlinestu- material, assisted problem solving, laboratory, films, dent response processing. A student should, ina proper- studentaccessed demonstrations, etc.to master the ly designed program, be able to come toa terminal, work material. Through the computer the instructorcan fol- through a multipart review problem, and have his low the progress of at least severalseparate classes of responses to each step evaluated at once. This offers students, give aid or stimulationas it is needed, and obvious advantages to either homeworkor exam prob- generally concentrate on whata human instructor does lems for which evaluation comes long after the student bestusing knowledge of his subject and his pedagogi- has attempted the solution and is necessarilymore a cal experience to teach the student at the student's level judgment of the whole than of theseparate parts. of understanding. As far as its mechanical capabilitiesare concerned, the computer can provide muchmore feedback than The Student is now normally available. Itcan (if desired) record everything the student does while signedonto the Little is known about the effectson the student and machine. The problem will beto decide what data the learning process of computerized instructionin to accumulate and how to organize its presentation. physics. By examining the problems and potentialities The feedback is useful in three generalways: as a from the student's viewpoint, however,we can perhaps guide to the instructor in presentingnew material make some suggestions toward fruitful directionsof and reediting material already presented;as an indi- development. cator to the student of his weaknesses and strengths; As a study aid, the computer will permit the student and finally, for cumulative bookkeeping of student to be a more active participant in the instructional sys- progress available to the teacher for administrative tem. An imaginatively constructed computer sequence purposes. To this latter category of information could can allow him to test himself at as fine an interval as be added a scholastic history of the student: hiscol- he desires and to continually evaluate hisown under- lege board scores, high school standing,high school standing. It should also allow him,to a certain extent, physics preparation, ifany, professional interests, etc. to pace himself, to call up more advanced parts of the The possibility of reducing the delays in feedback program as he has absorbed and understood previous and increasing its amount and usefulness (through portions, and to repeat portions of theprogram which better organization of theraw data) is exciting. To he finds difficult. realize this, however, the art of programming will A computerconducted recitation section has the have to be further refined; the studentmust be al- advantage of privacy: the student need not fear the lowed, for instance, to record his need for further direct reaction of his peers and professorsto his mis- information or explanation atany point. New inter- takes. He will, of course, recognize that each mistake face techniques, and perhapsnew equipment will have may be recorded and made available to his instructor; to be developed to allow for storage of the growing but the length of time he requires toanswer any one student history and to facilitate its quick readout and question need not be open to immediate criticism; and efficient presentation. a wrong answer, rather than triggering immediate dis- In addition, there is the intriguing possibility that approval, can be corrected by the student, allowing the maturation of this instructional element, with its him to proceed. ability to hold many reins atonce, may enable the The computer can in this way lead the student to instructor to allow the entire format of thecourse to discover his own strengths and weaknesses and to depart from the present lecturedominated lockstep. detect the stumbling blocks that might otherwise in- If the full capabilities of the computerare used for hibit his progress and discourage his desireto learn. keeping close watch on theprogress of individual stu- With skillful programming, the CAL. materialscan dents, a flexible pacing, determined toa greater extent help the student overcome these difficulties. than at present by the student himself,may be pos- Finally, because the instructor will constantly be sible. The instructor would set the intermediate check evaluating student performance at the machine,exam- points and the final goals of understandingupon which ination may become in parta continual process and

11 thus a potentially less painful experiencefor the cost of terminal and interface equipment, it isenor- student. mously expensive. In most instances,the cost of the We know least about the student's emotionaland central computing system will haveto be justified and psychological response to computerpresentedinstruc- amortized by research and administrativeneeds and tion. Results of student reactionsto the few programs not by its student use. The realizable costper student already in existence aresparse and inconclusive. They hour of a central computer utilizedoptimally has been indicate only that programmersmay have to develop estimated by Karl Zinn:3 more sophisticated response recognition techniquesto allow students more latitude in theiranswers to com- A commercially availablecomputer programmed to puterdirected questions, and ,thatmost students re- handle students at twelve electric typewritersinteracting quire a thorough introductionto the machine and its simultaneously with any oftwenty different courses costs under $10 per student hour operation before being askedto communicate with it at the teaching station. A smaller and less expensivecomputer shared by four in a learning situation. We recognize thatfor years to student stations can be operatedat less than $5 per hour come physics programs for the computer will be experi- per student. .. . Within three to five years, timeshared mental. The student's education should not be dis- systems will cost about $1 per student hourat the teach- rupted for the purpose of using himas a guinea pig. ing station. We recommend that new materials incomputerassist- These cost figures assume that much instructionalmate- ed physics instruction either bedeveloped around rial is already stored in the computer and thatstudents topics which do notnow form an integral part of the are scheduled to occupy all terminals for eight hours of physics curriculum or that they be appliedto course computer time five days a week.. . . Once the initial in- elements not now adequately exploited.In this way, vestment in the preparation of selfinstructionalmate- the student's progress towardan understanding of fun- rials has been made, teaching stations connectedto a damental physical concepts willnot be impeded if for timeshared central systemcan be used as very economi- some reason a computer program fails to provide the cal teaching assistants. proper guidance. Certainly in its early stages and forsome time after- We recommend also that the accumulated experience ward the cost of preparing CAL materialswill be more with students be recorded inas much detail as possible important and more difficultto estimate than the cost to provide guidelines to future program authors. of physical equipment. Thecost in terms of time and money will be shared by the university administration The Administrator and the author. The teacher and the student willmeasure the efficacy Programming instructionalsequences, especially tia of CAL against a constant standard: theimprovement the developing phases of theart, will require the efforts in learning efficiency. The administrator willuse an- of physicistinstructors,computer experts and pro- other yardstick. He must be concerned witheconomy grammers, as well as substantial technical and clerical and in this measure must includenot only instructional support. Commitments of money, personnel, andspace hour per dollar but also themore difficult measure- will have to be made for rather long periodsof time; ment which might be loosely termed excellenceper estimates of the ratio of professionalmanhours of pro- dollar. Before the administratoraccepts CAL, he must duction to hours of student consumptionare in the be convinced that its effectiveness justifies itscost. Such neighborhood of four physicistyearsper student se- a measurement will be difficult to make. mester. The cost of the development of CAL tech- The new kinds of costs that the introductionof CAL niques will have to be heavily subsidizedby govern. techniques will put on administrative booksare rather ment agencies, private foundations, publishers, and easy to enumerate. On the other side, however, the manufacturers. Efficiency andeconomy will call for ledger must be balanced not only by thegain in under- concentration of efforts atcenters offering excellent standing which the teacher will demand,but also by computer facilities and personnel resources. gains in the more elusive qualities which affect the Private authorship will raise problems ofcompensa- overall atmosphere ofa place of learning. tion different and more complex than those occasioned I. The Cost of CAL 4.1K111==r7JINIIMIIR As Appendix B indicates, CAL equipmentis expen- 3 Karl Zinn, "Computer Assistance for Instruction: An Introduction"(un- sive. If the cost of the published paper, 1965), pp. 2-3, available from Dr. Zinnat the Center for computer itself is added to the Research on Learning and Teaching of The University of Michigan.

12 by textbook writing. The preparation of CAL material educational system. The administrator will haveto will require more time than the afterhours allotted to make certain that the interposition ofa terminal and a text writing. CAL authorship will require substantial program between student and teacher, in drill and reci- released time, the use of student terminals, computer tation for instance, is compensated for by richer associ- facilities, and students for testing. Part of the incentive ations elsewherein seminars, student research involve- for authorship can be supplied by royaltyarrange- ment, etc. If the full potentialities of the computer to ments. This will be particularly necessary for programs examine each student individually and to record and developed at one institution and used at another. In analyze his development are used to advantage, and if these arrangements the home institution, providingas the instructor deals with the student from this deeper it must a large share of the physical and financialsup- insight, the educational experiencecan become a more port, would reasonably share in the royalties. personal one.

2. CAL and the Educational Atmosphere Recommendations Even were he able to design a measurement of under- From an administrator's point of view, whatrecom- standing per dollar, no administrator would dare make mendations should be made to guide the trial develop- this the unique measurement of CAL's effectiveness. ments that are now beginning? The first physics mate- He must in some way gauge the changes that the intro- rials programmed should be modular, accompanying duction of this new system will bring to the overall only part of a course. This will facilitate comparison of nature of his institution. It is impossible to anticipate results with those in other sections of thesame course all of these changes at this early stage. We can only and make their trial at other institutions easier. The suggest a few examples. administrator should demand that the development of The expectation that students will spend a signifi- physics programming techniques be paralleled by the cant number of hours at the terminal must be reflected development of a capability for sophisticated record in an overall reduction of hours spent elsewhere. The keeping and analysis so that this aspect. of CAL can be realization of some of the possibilities of more flexible evaluated. Finally the administrators of institutions pacing may suggest changes in the regular allottment beginning experimentation with CAL must provide of course hours. the imaginative leadership to work with funding agen- The most important concern may well tome from cies toward resolution of the complicated financing and apparent (or actual) further depersonalization of the compensation problems which will arise.

13 NOTFILMED Pedagogical PAGEBLANK- PRECEDING

Techniques'

The report of the Working Group on Pedagogical tional program, quantitative. and analytic techniques Techniques is divided into two sections. The first, com- can complement and illuminate one another.3 putational mode CAL, illustrates some of the ways in The speed of computer solution enables the student which the computer can expand the computational to examine many more specific problems than he could possibilities open to students. The second, instructional reasonably be expected to solve by hand calculation. mode CAL, considers the computer as a direct aid to The computer can thus increase his experience with, instruction. and intuition for, various physical situations. Furthermore, the use of numerical analysis permits Computational Mode the instructor to consider material which analytically The computer is fast becoming an indispensable sci- would exceed the student's level of sophistication. For entific tool; it is rapidly being acquired by colleges example, with the help of a computer, a teacher can throughout the country not only for research but also discuss the Schrodinger equation for the harmonic os- for all forms of computational and data processing cillator even with beginning students.* assistance. Understanding of the capabilities and limi- Finally, the fascination that computers hold for most tations of this computational aid, the logic of its oper- students can and should be exploited for pedagogical ation, and the mathematical techniques suitable to it, purposes. is, along with some experience in its use, a necessary Identifying the parts of a physics course that lend part of the training of the prospective physicist. We themselves to computer assistance and developing the suggest here a use of the computer in instruction which necessary programs for physics may well present serious can provide this familiarity and at the same time ex- barriers to further use of the computer as a computa- tend the breadth and depth of physical problems open tional tool for students. We recommend that there be to solution by the undergraduate student? a method of rapidly distributing and exchanging infor- By solving complex physical problems with a com- mation on computer programs already developed of puter, a student can gain experience not only with the sort described in Appendix E. This could be done analytic relationships and analytic methods of treating in the form of source program listings in any of the a problem, but also with actual numbers and with semistandard compiler languagesFORTRAN, AL- numerical methods. In a properly conceived instruc- GOL, BASIC, JOSS, etc.supplemented by short ab- stracts describing how the programs could be used in I Donald Brown, Chairman; Alfred Bork, Leonard Jossem, Arthur Luehrman, Thomas Padden, Donald Shirer, Malcolm Strandberg (Computational Mode sub. physics teaching. Many such programs already in committee); Arnold Arons, Kenneth Davis, Wallace Feurzelg, John Fowler, existence could easily be adapted for use at institutions Frank Harris, Robert Hulsizer, ThOira: Palfrey, Richard Walther (Instructional Mode subcommittee). *See Appendix E for detailed descriptions of five examples of programs in a See Appendix E (the Lattice Vibration Spectrum). which the computer has already been used in this mode. 4 See Appendix E (the Harmonic Oscillator in Quantum Mechanics).

15 other than the originating school. If the efforts of indi- Using a computer, an experienced teachershould be vidual physics teachers to developnew materials are able to prepare a program which anticipatessources of made available through the American Journalof student confusion and, by pointingback to previous Physics, the Commissionon College Physics, or through problems, to lectureor text, or by providing the next some other means, physics instructors will hopefully be smUll step, removes the difficulty andallows the student able to draw on a repository of ideas and materials for to proceed on his own. Some grading mechanism could computer-assisted physics instruction in much the be developed, basedon records of each student session, same way that they now draw on collections of lecture if desired. The optics unit producedat the Seattle demonstrations and laboratory experiments. Conference° and described in Appendix C hasas one of Appendix E may be consideredas the first edition of its elements the first approximationof a computer such information for computational modeprograms. program designed to give helpon assigned problems. The CCP accepts the responsibility of seeing that this A second type of computer-guidedprogram for list is kept up to dateas more programs become avail- problem solving might bemore tutorial in nature. For example, a CAL unit might be immediatelyvaluable Instructional Mode " between the time the student attendsa lecture and the time he is examinedon the material. Creative use of The use of computers as direct aidsto instruction, CAL to provide an opportunity for review rather than as computational devices, has and self- had little testing, perhaps in conjunction with otherprogrammed application in the teaching of physics. Instructors and materials, could allow the conscientious butuncertain administrators will judge the importance of thecom- student to better prepare for theexam hurdle. puter as an instructional tool, but they will doso only after comparing the cost and advantages of CAL tech- Diagnosis and Tutorial-Remedial Help niques with those of such existing materialsas pro- grammed texts, autotutors, conventional audio-visual We see considerable use for CAL materials of the aids, and of course text, lecture, and recitation.In this tutorial-remedial type. These routinescan be of a section of our report,we shall try to identify those straight remedial nature made availableto the student instructional elements5 whose functionscould be better for diagnostic purposes, for self-placement,or for help exploited with the help of thecomputer. in correcting deficiencies. Such help would bemost use- The computer seems to be poorly adaptedto straight ful early in a course when differences in preparation presentation of ideas; itoperates most effectively as a are the most disadvantaging. The programmed kik> response processor and is uniquely suited to collecting, matics unit described in Appendix C isa primitive analyzing, and presenting feedback information.We example of remedial use. describe below the instructional forms inwhich the CAL diagnostic techniques could be devised to help computer might supplement or supercedean inefficient the student find his areas of weakness andto then mechanism, or open upa new possibility in learning. branch him to a remedial loop. The particular advan- assistance. These CAL formsare considered in descend- tage of the CAL mode here is in the urea of what ing order of priorityas we see it at this stage of develop- Arnold Arons has called "the tricky,difficult and ment. blocking ideas" which are not necessarily complexor advanced, for example the "sensation of weightless- Guided Problem Solving ness"for which Arons has constructeda tutorial There seems to be general agreement that themost sequence.? The value of CAL modes for presentation keenly felt student need, and the need for whichhelp of such material is that the studentcan take as much is most difficult to come by, is for day-to-dayassistance time as he needs for understanding. Furthermore,an in problem. solving. It is in this exercise thatthe stu- idea can be presented in a wide variety ofways to help dent tests his understanding of the material presented clarify those points which later in the course often in lecture and text, and gainssome numerical familiar- cause great confusion. ity with physics. It is here also that individualattention of a rather routine form could be MIN most useful. *Working Conference on New Instructional Materials held at the University of Washington during summer 1965. *See Table 1 (p. 10) for a breakdown of the traditional elements ofa physics 7 This tutorial program is described in Appendix C and a complete flow diagram course into its three modes: presentation, response, and feedback. showing its logical structure forms Appendix J.

16 Computer Laboratory hardware and software which would facilitatethe ac- complishment of these purposes. In general we feel that although the computeraided Hardware that will allow inputto the compiler as laboratory has much to recommend it, the advantages typed words or typed algebra is essential.In addition, can easily be exaggerated. The computercan be used graphic input with lightpen or tablet sketch pad to present the student with problems which he solves would be immediately useful. at the lab bench and presents at the terminal for veri- Especially in the earlystages of program develop- fication. At this point he is branchedto one of a ment, online communication between author and variety of subsequent operations dependingon the student and online editing will benecessary. adequacy of his findings. Sucha sequence is being One would occasionally wantto use pagesize dis- tested in the optics unit mentioned earlier. play capability for quick presentationof text. For this, The computer could also be interposed betweenthe teletype seems too slow. "Thumbthrough"paging in student and a particularly dangerous experimentor both directions for successive developmentof diagrams one using equipment too expensive to jeopardize. The and the capability of monitoringthe page usage for student could then be given relative freedomto run author records are also desirable. the experiment and collect data, butwith builtin The software must complement the hardware,and protection for himself and theapparatus. must provide for information storage and quick and Obviously the use of computers inany of these ways easy retrial editing. A compiler eventually capable of could reduce the numbers of laboratoryassistants re- keyboard recognition, algebraic checking,and natural quired and provide increased flexibility in labschedul- language processing will be needed forthe sophistica- ing. Labs could be open for longer hours;Stony Brook, tion anticipated. for example, is looking towardat least sixteenhour scheduling periods. Questions and Recommendations It has been suggested that a CALprogram could be written to simulate laboratory experiments.We would, The working group raisedone question basic to the however, counsel strongly againsttoo much reliance on use of the computer in teaching; namely, have CAL the computer for such a task. It is largely inthe lab- techniques a significant advantageover those possible oratory that the student is introduced to the real with the much less expensive printed programs?A world of physics. He should have the privilegeof inter- convincing answer to this can only be made afterreal acting with real objects of that world andlearning the comparative trial, Asan exercise to provide some in- h. look of real data. It isour feeling that the computer sight, however, we simulateda tutorial dialogue,s in lab, other than for computationalpurposes, should be the course of which two advantages of CALtechniques used only in ways whichassure this contact with the over programmed text became apparent. First,com- phenomena. Simulation is useful only whenthe model puter presentation allows the student to constructan itself has some significance (ina Monte Carlo compu- answer and this constructed answer need not be in- tation, for instance)or perhaps to reproduce an experi- fluenced by a list of possibleanswers; nor is the ment not accessible to a particular laboratory (simu- student exposed to the correctanswer. Second, trial lated nuclear scattering). assays on the student's part are encouraged and do not Finally, the committee felt that physics laboratories affect the eventual judgment of the instructor. These are often too rigidly organized, forcing all students into gainsespecially the firstseem to be important. To the same program. With imaginative programmingthe them should be added the fact that the computer's computer could be used to assess each student'sprog- branching capacity vastly exceeds that of the printed ress and allow him to be placed at the appropriate program. The hopedfor ability of the computer to level and to proceed ata pace more nearly his own. S In this simulated tutorial dialogue Arnold Arons playedthe role of a com- puter terminal and Robert I. Hulsizer acted za the hypothetical student. The student approached the terminal for help on the following problem: "A rocket Required Hardware and Software of initial mass M. exhausts its fuel at a fixed velocity,vp, relative to the rocket, and at a constant rate of m. It is shot vertically upward. Neglecting Our considerations of the pedagogicalpurposes to earth rotation, find what determines the final rocket velocity,vt, and what val- ues of vf are possible." The remainder of the experiment took the form ofa which a computer might profitably be turnedhave led questionandanswer dialogue of the type which might be programmed and which resembled the kind of questioning an experienced teacher mightuse when us to compile a brief list of desiderata in terms of responding to a student's request for help on a problem.

17 allow the responses to take the form of diagrams, 3. The aim of CAL techniques should betoward numerical answers with a range ofcorrectness, or alge- the preparation of the student forindependent braic statements with a computercontrolled decision study and toward the increase of hiscapacity for as to their correctness, will further increase its ad- selfdirection, creativity, and understanding.There vantage. is a fear that enthusiasm for thisnew technique will We suggest that the following principles should cause authors to program too finely and toattempt typify the spirit of CAL development. to lean too heavily on CAL, and thus to interfere 1. CAL materials should not be introducedcasu- dangerously with the ultimate goal of physicsin- ally into an existingcourse format. They must be structionnamely, the development withinthe in- integrated with the other instructional elements,and dividual of the capacity for selfinstruction. this can be expected to require considerable reformu- lation of the mechanical structure of teaching. 4. Not all students should be requiredto take all The time spent on studentteacher interaction, parts of a CAL program. Oneconsequence of the availability of CAL would be to increase the laboratory work, discussionrecitation sections,out- modes side reading, problem solving, of learning available toa student. Indeed, one of etc., will have to be the strengths of the automated instructional reexamined. At present we cannot make reliable esti- system mates of how the students' and instructors' time is that it gives the instructor freedomto provide a would be affected. Information will become available greater variety of instructional opportunities and as trial courses are formulated and tested. educational environments, both within thesystem and outside. But students differ in their abilityto 2. Computerpresented materials shouldnot be interact with differing teaching modes andto profit expected to carry an entire college physics'course. from them. CAL should be viewed asan exciting new technology that deserves further exploration and exploitation, We urge that the physics profession and the CCP in but only as one of several teaching elements.It particular support vigorous experimentation withthis should be integrated into present modes where itcan promising technique. Only by careful planning from clearly offer better and/ormore economical ways of the beginning can we assure that technology willenter teaching. The increasing problems of enrollmentand teaching as it has entered otherareas of human en- shortage of trained personnel make suchan effort deavor, not as a substitute for humans butas a' means almost a moral demand. of amplifying the uniquely human contribution. Systems

and

Equipment'

The Systems and Equipment Groupreport is de- sophisticated remote console devices (e.g., Teletypeor signed to guide departments of physics which havenot IBM 1050), simple computationalcourse material could as yet devoted significant attention to the use of com- be prepared for experimentaluse with small classes in puters in undergraduate physics instruction, but who the fall of 1966. Examples of such dialablecomputing wish to do so in the near future. In particular,we are systems are JOSS{ at RAND and System Development talking to those departments located ininstitutions Corporation (SDC); modified versions of JOSSat the having no strong currentprogram in the general field University of California at Irvine andat Bolt Beranek of computer-assisted instruction. and Newman; BASIC{ at Dartmouth; and commerci- We have attempted to characterize briefly' the equip- ally-available service in QUIKTRAN4 from IBM and ment and systems currently available for use withstu- BASIC from General Electric. Amore sophisticated dents, and then to indicate the principalneeds and capability, such as Glen Culler's on-linesystem at the possibilities for action in computer-assistedphysics University of California at Santa Barbara (described instruction this fall (1966). Finallywe consider the in Appendix F), involvesa more elaborate remote con- equipment and systems needs of those whoaim for sole, but can still operate over telephone lines. Infact, operational status in the fall of 1967or 1968. Beyond consoles connected to the UCSB system via phone line 1968 our crystal balls are not cloudy; theyare opaque. are currently in operation at the University of Cali- It is clear to us that any system to be operational fornia at Los Angeles and at Harvard University. by the fall of 1966 must makeuse of presently existing For those who seek to develop physicsprograms for hardware and software. For example, itappears that use in fall of 1967 or 1968, the possibilities are much prospective authors withoutaccess to one of the ex- more extensive. As we discuss these possibilities, we perimental user languages haveno choice but to use make the assumption that a central computer is avail- COURSEWRITER2 for the preparation of instruc- able, either locally or through a communication line, tional materials. and recommend that it have the following features: For computational mode CAL, however,new users first, hardware to permit time-sharing operations;sec- can arrange access to one of a number of already ond, an adequate complement of time-sharing soft- operational dialing systems. Usingone of the less ware for housekeeping operations, monitor operation, computing languages, interpretive schemes, and soon; 1 Burton Fried, Chairman; Bruce Arden, Charles Branscomb, Harry Cantrell, Richard Gooch, Everett Hefner, John Kaibach, Andrew Kleinschnitz,William third, modular design so that the machine may be Lonergan, George Michael, Peter Roll, Noah Sherman. readily expanded; and fourth, a direct-accessmass : Detailed information appears in Appendix A ("Linguistic Mode Computer Systems"), Appendix B ("Remote Console Equipment"), and AppendixC ("Linguistic Mode Physics Programs"). See Appendix G for brief descriptions of these computational programming a See Appendix A for a brief description of the COURSEWRITERlanguage. systems.

19 memory including disk, drum, and data cell storage, As additional options for thismore sophisticated or some combination of these elements. We estimate kind of console one could includean output writer that there will be approximately twenty such machines and a plotter to give permanent "hard"copy ver- in operation by fall 1967 and approximately fifty by sions of the graphic displays, anda graphic input fall 1968. These will be distributedacross the country device such as Bolt Beranek and Newman'sGrapha- in such a way that by 1968every institution will be con and the RAND Tablet. Note that these options within 500 miles of a machine. do not include such dynamic graphic displaysas the MIT SKETCHPAD and similar developmentswhich Characteristics of Student Console Systems typically involve the CRT presentation ofrapid Given this general geographic availability of large motion-picture-type displays. time-sharing computer systems, what kinds ofremote Economics may require that thesemore elaborate and local consoles can be used byan institution which devices be driven in parallel, in thesense that one seeks to enjoy some of the facilities ofa system located piece of remote interface equipment servicesmore as far away as several hundred miles? Without at- than one independently-active console. Moreover, tempting to include all possibilities,we can categorize some of the optional devices, such as the output such consoles, in increasing order ofcost and capability, writer and plotter, can serve several of the standard as follows: consoles simultaneously. 1. Remote consoles which can be servicedover a 3. Local consoles located with a few thousand feet telephone line alone, and for which,at the user's of the computer. All options given under 1. and 2. end, no logical circuitry beyonda standard telephone above are of course available, but the economic data set is required to connect the consoleto a factors %ay in some cases be quite different. In telephone line. Examples includea conventional addition, the very large data transfer rateover a input-output typewriter ora typewriter together short transmission line makes possible dynamic with a paper tape reader and punch, which allows graphic displays which are not feasible overa tele- users at the remote location to prepare small pro- phone line. It is clear that many other things could grams on paper tape and to load them into the be done with local consoles which will not be possi- computer. Consoles of this kind are commercially ble with remote consoles within the next twoyears. available (see Appendix B). For example, in a local console visual displays are possible using inexpensive commercial TV receivers. 2. Remote consoles which operate over telephone These would permit the presentation of pictures lines but require some equipment at the user's end with the fine detail of commercial television,as well to interface the console to a standard data set. We as the display of text at a rate far beyond the reader's will outline here three examples of such consoles. power of absorption. It is nevertheless our sugges- The first is a typewriter combined witha visual dis- tion that restraint be exercised in developing course play device such as a slide projector, andan audio materials making essential use of facilities which device such as a tape recorder. (Experimental equip- cannot feasibly be enjoyed by remote users. This ment of this kind has been developed by IBM and does not rule out experimental work involvingcom- by the PLATO project at the University of Illinois plex displays, nor does it restrict course development [see Appendix A].) The second combinesa keyboard in which TV text displays are used locally, with (i.e., no output writer) withan oscilloscope capable some sort of permanent copy display (e.g., slides or of generating alphanumeric characters only.The video tape) at remote terminals. third consists of a keyboard withan oscilloscope capable of producing not only alphanumericchar- One or two remarks about the economics of consoles acters, but also such graphic displays as curves and are in order. What number of consoles would be suffi- other two-dimensional plots. (Consoles of thistype cient to handle a class of freshman students? At The using a storage oscilloscope have been producedby University of Michigan, for example, it appears that Bolt Beranek and Newman andare currently in use fifty to one hundred consoles would be required just at UCSB, at the Harvard Computer Laboratory, and for physics. This seems to us to be economicallyun- at the UCLA physics department.) reasonable for the next few years for most institutions.

20 'IMItielettrtelebeilWatthaMatit

Aside from economic considerations, the lackof tested be required if such equipment isto be available at a physics material at the present time makesit undesir- reasonable cost two years fromnow. able to consider widespread, largescaleuse of com- The activities described above will typicallyinvolve puterassisted instruction. During thenext two years a cooperative effoi t among several institutionson a or so, however, it should be feasible fora department statewide or perhaps regional basis. Weexpect that having local or remoteaccess to a central computer to neither the user departmentnor the computer facility use ten or fifteen consoles. This number should be will be able to bear a large fraction of thecost at sufficient for the development of instructionalmaterial either end of the communication line, andthat sup- by the staff, for limiteduse with large classes of some port from appropriate federal, state, or private organi- materials already produced and available,and for zations will be necessary. It is importantthat this more general instructional use at the intermediateor situation be brought to the attention ofthe National advanced level. Science Foundation, the Office of Education,and ap- propriate private foundationsso that they realize the Recommendations . technological possibilities and the necessityfor provid- ing funds on a sufficiently broad basisto allow this For those who intend to begin usingcomputeis for kind of cooperative action. physics instruction in the fall of 1967 and 1968, we We feel that working sessions devotedto the develop- recommend the following actions. First,physics de- ment of and experimentation with the partments (or any other potential users) should new kinds of ar- software and hardware discussed abovecan make a range in the near future for cooperativeuse of a distant valuable contribution to the development central computer, or should initiate of CAL in appropriate action physics. It is therefore recommended thatone or more to secure the necessary computing facilities locally. If small working groups be organized for thesummer of the latter choice is made,users should remember that 1966,5 as well as for the following the lead time for summer. a new system (including the raising One action which can be taken by departments of funds, selection and ordering ofequipment, and so which have not previously attempted on) is likely to be at least to work in the two years. area of computerassisted instruction for undergradu- Secondly, developmentor acquisition of software ate physics is to have staff members visit one of the appropriate for physics instruction (author languages, centers mentioned in Appendix A, where facilities and instructional programs, online computinglanguages, experimental programs are in and §o on) should be initiated. use. Visits of a few weeks or more would enable interested staffmembers And finally departments should choosethe type or to experiment with the instructional material avail- types of consoles which will fit their needs.Prompt able, to make judgments concerning its adequacy and specific requests to manufacturers for for such con- their needs, and to suggest the kinds of improvements soles are indispensable if equipmentthat is techno- they would like to see available at the time theyac- logically feasible and functionallydesirable is to be- quire their individual consoles. come available within the time scale considered. The Report of this Conference containsa reason- The professional staff of the central computing facil- ably complete listing of the physics instructionalma- ities, whether local or remote, have theobligation of terials which have been prepared to date. We providing an adequate interface, both recom- hardware and mend that the Commissionon College Physics or some software, between the computer and theremote con- other group keep this listingup to date, publicize soles. In the light of present technology this interface future additions to it, and arrange.:ome means for problem does not appear to bevery difficult, but it communication and exchange of materials must receive adequate attention. The consoles de- between the developers of instructional materials andprospec- scribed above are, as already noted, technologically tive users. feasible on a relatively short time scale.Nevertheless only a few of them are presently commerciallyavail- 8 This recommendation has been carried out;groups will be working at the MIT able. A concerted effort by the Science Teaching Center and at the Stony Brookcampus of the State University computer industry will of New York during the summer of 1966.

21

Alr ^ ExE.,

NOT. FILMED PRECEDINGPAGE BLANK- appendices

Linguistic Mode Computer Systems

Remote Console Equipment

Linguistic Mode Physics Programs

Four University-Based Systems

Computational Mode Physics Programs

University of California, Santa Barbara, Computer System

Computational Mode Computer Languages

Glossary

List of Participants

Flow Diagram:"Weightlessness" by Arnold Arons appendixa PRECEDING,SAGE KANK-MIE11.1E-D

Linguistic Mode Computer Systems

Three large-scale systems exist at present (early at the 1050 terminal, the computer interprets the stored 1966) which are suitable for the preparation of com- instructions to present reading assignments, questions, puter-assisted instructional material in physics. Of and replies to student answers. The student types the these, the only one currently available over telephone responses he has constructed on the keyboard, and linesis the IBM COURSEWRITER system. Bolt these responses are entered into the computer for com- Beranek and Newman's Socratic system using the MEN- parison with alternatives previously stored by the au- TOR language has been tried experimentally in medi- thor: the match between student answer and computer cal diagnosis, but has not been used for physics. It alternative determines the next computer reply. In may become available in the near future on BBN's achieving a match, the author can specify a variety of new time-sharing system. The University of Illinois' conditions for recognition of responses other than an PLATO system will soon be available to a fewco- exact match, including the presence of a portion of a operating institutions over telephone lines. In addition given list of items, and the ignoring of trivial charac- to these three rather sophisticated systems, a simple ters, such as space and tabulation, in the student re- question-and-answer language, COMPUTEST, has sponse. The operating system consists of a monitor, a been developed for the IBM 1620 computer. Finally, compiler, and programs to handle student registration an author language is under development at System and record keeping. This latter feature permits the Development Corporation (SDC).2 author-experimenter to accumulate and summarize data on student performance and on characteristics of The IBM COURSEWRITER System particular items or sequences in the instructionalpro- In brief, COURSEWRITER is an interpreter lan- gram. guage of about twelve executable instructions or oper- Detailed specifications for the 1050 teaching terminal ation codes and ten manipulative commands by which can be found in Appendix B. Briefly, it consists of a an author at an IBM 1050 terminal enters and edits Selectric transmitting typewriter plus (optional) facil- text material and branching logic into the disk storage ities for random access visual and audio files under of an IBM 1401, 1440, or 1460 system. The edit com- computer control. Transparencies showing text, dia- mands include insert, delete, and type, and can refer- grams, or photographs of lab equipment can be dis- ence text by line only. When the student is operating played with an 80-slot Kodak Carousel Slide Projector, and recorded messages can be played from a tape 1 The following brief descriptions have been abstracted, with a little editing, from a paper prepared by Karl L. Zinn for the Association of Educational recorder which can be separately addressed for any Data Systems Conference on Computers in American Education (Stanford Uni- message of ten seconds or more anywhere on a thirty- versity, November 1-3), 1965, entitled "Computer Assistance for Instruction: A Review of Systems and Projects." In Proceedings of the AEDS-Staxiord Con- minute length of tape. ference on Computers in American Education, edited by Don D. Bushnell and The commercially-announced version of the the Dwight Allen (to be published in 1966). COURSEWRITER system is available on the IBM 2 See Appendix D for a summary of how UCLA intends to use this programming system. 1401, 1440, or 1460 series of computers. The Watson

25 Research Center uses an experimental version with a The Bolt Beranek and Newman System timeshared 7010 computer using a 1440-1448 buffer multiplier inputoutput control system. Recently (late Researchers at Bolt Beranek and Newman are giving particular attention to a system in which an author March 1966) IBM has announced the existence of the & instructor can implement training and testing of series 1500 Instructional System, for which a more ad- complex analytic tasks, such as diagnosing medical vanced COURSEWRITER II language is available. ailments, arriving at decisions in business and man- The 1500 System has two significant advantagesover the 1400 series with type 1050 terminals. It possesses agement, developing military strategy, and investigat- a CRT output upon which characters and a limited ing scientific problems. For this they are developing, amount of graphical information can be displayed, a teacherauthor language called MENTOR for use thus overcoming some of the display limitations and in constructing conversational tutorial dialogues. The the slow speed of typewriter output. Secondly, the 1500 instructional program in this system is in the form System is less expensive than the 1440 series. An effi- of logical expressions which determine computer re- cient computational language, MAT (Mathematical plies and subsequent material on the basis of whatever aspects of the student performance history the author Algorithm Translation), will also be availableon the 1500 System. As presently announced, however, the cares to designate. Typically, a situation is established in which a problem may be solved by the gradual 1500 System will be available only to selected research laboratories for use in the development of instruc- acquisition of information. The student makes in- tional materials. quiries or declarations composed from a list of ac- ceptable terms, and the machine processes these replies Some of the locations where COURSEWRITERsys- tems are in use in early 1966 include Florida State according to complex conditional rules described by the author. In the current system, a PDP-1 computer University (Donald L. Hartford), Michigan State Uni- is used with a teletypewriter and occasionally with versity(R.Davis), Pennsylvania StateUniversity cathode ray tube display devices. (Harold E. Mitzell), The State University of New York Wallace Feurzeig and Daniel Bobro have described at Stony Brook (E. D. Lambe), the University of Cali- the ideal characteristics of a system for programmed fornia at Irvine (Fred M. Tonge), The University of instructional conversations between students and com- Michigan (Karl L. Zinn, Center for Research on Learn- puters, and have attempted to include these as far as ing and Teaching), and the University of Texas (C. possible in their systems: Victor Bunderson). Several of these projects donot have their own computer at present, butare tied into 1. The computer responds in terms of the previous the Watson Research Center by longdistance tele- portions of the conversation and in terms of the phone lines. A German course and several physicspro- question of the moment; grams (described in Appendices C and E) are among 2. The user has complete freedom, including the the materials developed for experimentaluse in the possibility of making irrelevant or inappropriate COURSEWRITER system. remarks; The following references contain further descrip- 3. The computer will always have something appro- tions of the IBM system: priate to say; 4. The computer can judge whether to delay in- T. Hartman, Audiovisual Instruction (January 1966) formation requested by the student; pp. 22-23. Thisis a popular description of 5. The answers of the computer can be based on COURSEWRITER, including examples from a complex computations, such as simulationsfor computerized German course. example, the student might suggest a military 1401, 1440 or 1460 Operating System for Computer strategy or tactic, and the computer could quickly Assisted Instruction (IBM, Endicott, N. Y., Sys- lay out an array of consequences; tems Reference Library Form C24-3253-1 [1965]). 6. Verbal interactions are in natural language, such as everyday English; A. Maher, ComputerBased Instruction(CBI): Intro- 7. Questions or declarative statements may be in- ductionto the IBM Research Project (IBM, troduced on either side at any time; Thomas J. Watson Research Center, Yorktown 8. Nonverbal exchange may include tables, graphs, Heights, N. Y., RCI114 [1964]). pictures, and sounds.

26 4."

Work on the MENTOR system is being carried out by John A. Swets, Wallace Feurzeig, and Daniel Bobro I at Bolt Beranek and Newman Inc., 50 Moulton Street, Cambridge, Massachusetts. A more detailed descrip- tion of their approach, together with an example of a medical diagnosis program, has been published re- cently by Swets and Feurzeig (Science, 150,572 [1965]).

The University of Illinois PLATO Project The PLATO (Programmed Logic for Automatic Teaching Operations) project at the Coordinated Sci- ence Laboratory of the University of Illinois (Donald L. Bitzer, Director) has developed a compiler language for writing teaching logics or patterns for their CDC 1604 system. It incorporates an extended FORTRAN ,, with theit:' Own language (called CATO) for specifying the logical structure of an instructional sequence, and can accept CDC 1604 assembly language statements at any point. Thereby, the programmer has great flexi- bility and scope for preparation of basic patterns (such as tutorial, inquiry, and simulation) into which any author can later insert his particular teaching mate- rial. For example, using a tutorial logic an author need write only the text, right answers, and diagnostics to the characters or special symbols appearingon the tele- obtain a computer-controlled sequence of instruction; vision screen at a location predetermined by the author the computer has been programmed in advance to fit or programmer. This television capability requires ex- arbitrary text and answers into a particular type of pensive wide-band (video) transmission lines between dialogue. In another pre-programmed strategy, the the central computer and remote terminals, thereby author may insert any text which he wishes to evaluate; effectively limiting full use of PLATO to the Univer- the computer has been programmed to ask questions sity of Illinois campus in Urbana. Arrangements have and collect data during presentation to students ac- been made recently, however, to make a more limited cording to a particular pattern. A third type of strategy version of PLATO available over telephone lines ata being explored is simulation of laboratory or real few other institutions. world situations such as international relations. To A wide variety of materials has been programmed accomplish these functions, special routines have been inthe PLATO system, ranging from pre-school written for judging student answers by various com- through graduate level. Programs have been developed plex criteria, plotting graphs on student request, plot- in a large number of areas for elementary and second- ting data from an on-line physics experiment, con- ary school use. At the college level, programs have structing and checking statements in a mathematical been developed in psychology and in several engineer- proof, monitoring physiological data entered over sup- ing subjects, and the system has been used on a semi-. plementary input channels, and controlling supple- production basis for engineering instruction. mentary audio or visual displays. Further recent published information on the PLATO The current operating system for PLATO includes project is available from the following references: twenty teaching stations with video capability. The R. Benjamin, "The Uses of PLATO," Audiovisual author may project slides on a television screen via an Instruction (January 1966) pp. 16-23. (A popu- "electronic book" and superimpose writing on dia- larized account.) grams by means of an "electronic blackboard function.3 Student response is by teletypewriter keyboard, with D. L. Bitzer and J. A. Easley, Jr., "PLATO: A Com- puter-Controlled Teaching System." In Computer See Appendix D for elaboration of these functions. Augmentation of Human Reasoning, edited by

27 Margo A. Sass and William D. Wilkinson, (Wash- COMPUTEST language permits the construction of ington, D. C.: Spartan Books, 1965), pp. 89-104. simple questionandanswer dialogues, includinga D. L. Bitzer, E. R. Lyman, and J. A. Easley, Jr., "The skipahead form of branching. It is characterized by Uses of PLATO: A ComputerControlled Teach- the ease with which a person untrained incomputer ing System." Report R-268, University of Illinois programming may write sequences of material. The Coordinated Science Laboratory (Urbana, 1965). common, inexpensive IBM 1620 computer with type- J. A. Easley, Jr., H. Gelder, and W. Golden, "A writer and card input/oinput is used. Preparation and PLATO Program For Instruction and Data Col- input of instructions to the computer are by punched lection in Mathematical Problem Solving." Re- cards; the typewriter serves as the student station. The port R-235, University of Illinois Coordinated system includes the capability of grading the student's Science Laboratory (Urbana, 1964). responses to questions. A more detailed description of this language can be found in: COMPUTEST J. A. Starkweather, "COMPUTEST: A Computer A simple, unsophisticated instructional author lan- Language For Individual Testing, Instruction, guage has been developed by John A. Starkweather of and Interviewing."Psychological Reports(in the University of California at San Francisco. The press).

F

28

AIL appendix b

Remote Console Equipment

I.INTRODUCTION improved models will have appeared between the This survey is intended to provide the following time this was written (May 1966) and the time it kinds of information to physics teachers and others is read. who are interested in the use of computers for instruc- 2. Price information is only approximate. It does not tional purposes, both in the linguistic and the compu- reflect educational discounts where available, and tational modes: could change in either direction according to mar- ket pressures and as improvements or modifica- 1. Simple descriptions of some of the remote termi- tions are incorporated into equipment. nal devices and communication links available for use with large, fast, timeshared computers, as 3. A remote console system cannot be designed from well as an elementary understanding of some of the information given in this report. The various the technical problems involved in using them; components described are not necessarily compat- ible with one another or with any particular cen- 2. Approximate cost information for these devices tral computer. Programs may not be available to and links, to provide some feeling for the overall utilize some of the devices with a given computer amount of money involved in using remote com- puter console systems; and or with any computer, and they may have to be developed at the expense of the user. In short, any 3. Illustrations of possible uses of some realistic re- system which is to be optimally effective and eco- mote console equipment, in order to stimulate nomical must be designed in collaboration with further interest, thought, and activity on the part computer specialists, communications engineers, of physicists. and manufacturers' sales representatives. Along with these three objectives, the following limita- tions of the information must be emphasized: Despite these limitations, it is hoped that the survey will provide a reasonably good general idea of the kind 1. The survey certainly is not complete. Although of remote console equipment available at the end of we have tried to collect as much information as 1965, what it will do, and about how much the various possible; some manufacturers have undoubtedly components cost. been overlooked, and the products of others sure- As illustrated in Figure 1(a), a remote console sys- ly are not completely represented. Furthermore, tem, for either instructional or research use, may con- developments are so rapid that new products and sist of one or more inputoutput (I/O) terminals con- nected to a control unit. The terminals themselves I This appendix has been designed around a document prepared by Dr. Franklin consist of devices to permit the student to communicate H. Westervelt, of The University of Michigan Computing Center, for the use of his colleagues. To Westervelt's rather complete survey of devices manufac- with the computer, plus other devices to permit the tured and supplied by IBM, Digital Equipment Corporation (DEC), and the computer (or the teacher through the computer) to Bell Telephone System has been added some information on products of other manufacturers. communicate with the student. In the former class, for

29 1 (a)

Data Set Communication Controller: Data Central Set Line-to Computer Computer Buffer Unit

COMMUNICATION LINKS

CENTRAL REMOTE TERMINAL COMPUTING FACILITY EQUIPMENT 4,00".

#00ossiaNistio,

(b)

Data Data Set Set

Terminal Data Data Data Set #2 Set Set Control Central Unit Computer

Terminal Data Data #3 Set Set

I

REMOTE COMMUNICATION CENTRAL TERMINALS LINK COMPUTING FACILITY

Figure 1 Block diagrams of typical remote stationcomputer systems. (a) Several remote terminals connectedto the computer by a single communication line. (b) Remote terminals connectedto the computer by individual communication lines.

30 :4e1:11:ILY 1414 41;a1

instance, are keyboards and light pens (for the input of ordering by increasing cost. Because of the inter- graphic information), while output devices include dependence of terminal devices and communication typewriter printers, cathode ray tube (CRT) displays links, it will be necessary to refer to the latter in dis- for alphanumeric and graphic information, film strip cussing the former. Therefore, the reader must be pre- projectors, audio tape playback, and the like. More pared to skip back and forth until acquiring some complicated terminals require a control unit to process familiarity with both areas. the incoming and outgoing signals. For example, such For those not fluent in the language of the computer a unit may provide temporary (buffer) storage for CRT specialist, a brief glossary of some of the less familiar displays, control circuitry and logic to operate film pro- terminology is provided in Appendix H. jectors, typewriters, etc., and timesharing circuitry to permit the operation of several terminals from only one II. REMOTE TERMINAL DEVICES communication line. If such timesharing is required, Low Data Rate Terminal Devices as shown in Figure 1(a), some kind of control unit is These are devices which can be connected to the cen- necessary. On the other hand, if simple terminals are tral computer by voice grade or teletype communica- connected to the computer by individual telephone tion links. As will be more fully explained in Section lines, as in Figure 1(b), then the terminal can often be III, however, the designation "voice grade" refers both connected directly to the data set and communication to ordinary dialable telephone lines, over which data line (this is true of a teletypewriter, for instance). At the can be transmitted reliably at rates of less than 2.000 computer end of the line, however, some kind of con- bits/sec, and to special communication facilities which trol unit is always necessary'to sort out signals from and are designed to handle rates of up to 3,000 bits/sec or to the various terminals, to provide buffer storage for so. These special facilities include the leased lines them if necessary, and to put them into a form which lines available from AT&T (the Bell System) and West- can be interpreted by the central processor. (In some ern Union, which are conditioned by them to meet the cases this control unit may be built into the computer noise and bandwidth requirements of the user, and the itself.) Broadband Exchange Service of Western Union, a In order to condition data signals properly for trans- dialable network similar to the long distance telephone mission over a telephone line or other communication system but capable of higher rates of data transmission channel, a data set is usually used at each end of the according to the subscriber's needs. line. A data set is a telephonelike device with provi- The first four terminals described below typically sion for dialing another party and for voice communi- operate at rates of 1,200 bits/sec or less, and therefore cation between the two ends of the line (the remote can make use of ordinary local or long distance tele- location and the central computer). It converts d.c. phone services, and in some cases teletype lines. The pulses from the terminal or the computer into audio remaining terminals in this group either require or frequency tones for transmission over telephone lines, operate more effectively at higher data transmission and demodulates such tones into pulses which then ratesusually at 2,400 bits/sec. Therefore they require can be interpreted by the computer or the remote ter- specialfacilities:leased lines, broadband exchange minal devices, respectively. In other words, the data service, or even one channel of a wideband multi- set performs a generalized "impedance matching" func- plexed TELPAK line (see Section Ill). tion at each end of the communication link. The data sets on either end of the line must be compatible with 1. The "TouchTone" Telephone one another, with the devices to which they are con- 7,1,e touchtone (or pushbutton dial) telephone is nected, and with the line itself. prebably the least expensive, but fairly general remote This survey is organized to describe first, the remote terminal device. It consists of a telephone equipped terminal devices, including control units where neces- with pushbuttons rather than the usual rotary dial. sary; second, communication links including data sets; When the buttons are pressed, a combination of musi- and third, a visual display storage device which could cal tones is transmitted. Ordinarily this is used as a be located at the central computer facility or at a re- means of "dialing" the desired number of another tele- mote, multiconsole location. Within the first two cate- phone. Because the tone generators are contained in gories, devices are listed roughly in order of increasing the instrument, they may be used after the usual tele- rate of data handling, which is almost equivalent to phone connection is completed. Thus, itis entirely

31 feasible to use the pushbuttons to transmit data to the (teletype exchange service of Western Unionor AT&T, central computer after first dialinga special number. respectively). It is felt that the twelvebutton instrumentshould Typical costs (per month) ofteletypewriters leased be specified to allowa fairly simple transmission of from the Bell Systemare: alphabetic code as wellas numeric data, and to allow for error correction. Thecomputer would return re- Model TWX Service Data Phone Service2 33 KSR sults in spoken letters, digits, anti words usingan audio $45 $35 response device at, the central facility. 35 KSR $85 $75 Typical monthly costs ina university Centrex sys- 33 ASR $60 $50 tem are: 35 ASR $125 $115

Handset plus line $8.75 In addition, there isa nonrecurring $25 installation Twelve key touchtone feature 1.00 charge. The cost of identical units leasedfrom Western Union is comparableto the TWX rates. Thus, monthly $9.75 /month terminal costs range from $45$150.These terminals Other features to be considered are: may be used to converse with the timesharedsystem in a full range of applications. Programs might Extension phone be in- $3.50 /month serted, debugged, andrun with interaction occurring Exclusion feature (to prevent errors after a delay of perhapsone to five seconds, depending from other phones on same extension on load and priority, etc. during data transmission) $ .25/month Card dialer. (Allows transmission of 3. IBM Model 1050 Data CommunicationSystem precoded strings of tones [up to fourteen A more versatile (andmore expensive) terminal, the steps] from a punched plastic card. May 1050 is likely to become fairly popular.Operating over contain stop codes so that more thanone voice grade or teletype linesat rated speeds up to 14.8 string may be held on a card. Cardsare ASCII characters/sec (about 150 bits/sec),the 1050 may 5ce each. Used for rapid dialing and for be configured inmany ways to suit special needs and sending standard messages to logon, purposes. log off, etc.) $3.00 /month One begins with a line and dataset (at about $35/ month) and a 1051 control unit ($75 The touchtone telephone might be usedto supply $145 /month, de- pending on features) to allow 1050s data and get answers from a program preparedon to converse with other, more versatile terminals;or it might be used in one another without using the central computing facil- ity. One then may add various I/O the laboratory as a means of settingup communication devices as follows: between an experiment anti the central facility (see the 1052 Printerkeyboard $65/month brief discussion of process control units below). 1053 Printer only $50/month 1054 Paper tape reader $30-40/month 2. Model 33 and 35 Teletypewriters 1055 Paper tape punch $40-48/month The Model 33 TTY (Teletypewriter) isa lowcost 1056 Card reader $60-97 /month keyboard terminal able to send anti receivemessages 1057 Card punch $75 /month at 100 ASCII words/min. (The American Standard 1058 Printing card punch $95 /month Code for Information Interchangeuses eight bits There are system limits that control the numberof [eight-level paper tape] plusone start and two stop bits devices which may be attachedto each 1051. There are per character, a total of 11 bits/character. At 6 charac- also some charges for special features that will probably ters/word, the 100 wpm rate correspondsto 110 bits/ be part of any 1050 installation. sec). The Model 35 has thesame capabilities but is A typical keyboardprinter terminal willcost about designed for heavyduty continuoususe. Both the 33 $168/month plus line and data and 35 are available in keyboard send and receive set, or $203/month total. Adding paper tape reader and punchwill result (KSR) and automatic send and receive (ASR), thelat- in a terminal charge of about $290/month ter incorporating a paper tape reader and punch. This total. This equipment may be connected to the centralcomputer 2 Additional charges for Data Phone service are $8.75/month foran ordinary by ordinary telephone lines, telephone line and $25/month for the data set. Theextra features make voice or by Telex or TWX lines as well as data transmission possible.

32 terminal is a very flexible conversational device, allow- multiple data stations. When stations are close enough ing access to a full range of time-shared system applica- to the computer, data sets may not be required. tions. It is the type of terminal now in use in the IBM QUIKTRAN system, in the MAC (Multiple Access 5. The Bolt Beranek and Newman (BBN) Teleputer Computer) project at MIT, and for the IBM COURSE- Suitable primarily for CAL in the computational WRITER system. mode (as well as for use as a research tool), this termi- Some 1050 terminals used with COURSEWRITER nal has been described in some detail byone of its have been modified to include simple visual and audio developers, Glen j. Culler, in an invitedpaper pre- displays. A Kodak Carousel slide projector mounted sented at the Irvine Conference (see Appendix F). in the terminal is controlled by the central computer, Briefly, the console consists ofa double keyboard, one which can be programmed to display the slides loaded for function operators (sine, expon, add, mpy, etc.) and in the projector magazine. Similarly, a tape recorder one for operands, plus a five-inch storage oscilloscope can be mounted in the terminal to play back previously unit on which alphanumeric as well as graphic infor- recorded audio material under computer control. Since mation can be displayed. Details and examples of how these accessories are relatively new and still somewhat this terminal functions and how it has been used for developmental, no area prices are available. instructional purposes are given in Appendix F. 4. Honeywell Series 200 Data Station Although the BBN Teleputer is intended for opera- tion with full duplex 2,400 bits/sec communication This all-purpose communication terminal was de- links, it has also been used with ordinary dialable signed for business communication witha centrally- (2,000 bits/sec) telephone circuits. located Honeywell series 200 computer. It transmits Purchase prices of the various components of the and receives over a voice grade telephone lineat 120 system are approximately as follows: characters/sec, using a Data Phone 202C or 202D data set. The system is of modu3ar design and may include BBN Teleputer $5,000 keyboard, printer, paper tape reader and punch, card Teleputer Control Unit reader, and optical bar code reader. The data station Standard model (handles up to can be used off-line for such activities as data prepara- 16 terminals) $25,000 tion and editing. In many respects it is similarto the Improved model (handles up to IBM 1050 series equipment, although it hasnot been 32 terminals with improved adapted for use in an instructional system. vector generation characteristics) $40,000 The monthly costs of components in an H-200 Data Western Union or Bell System 201B Station system are approximately as listed belowon a Data Set $70/month ninety-day lease basis. Somewhat lower rates prevail Data Set Controller Unit (may be necessary for longer leasing terms. with some central computers) $10-20,000 288-1 Central Control Unit (the basic terminal, Printer Output (Teletypewriter) $2,500 which connects to data set and telephone X-Y Analog Output Plotter $2,000 line) $155/month (p, 0) analog-to-digital input arm, for Keyboard $30 /month input of graphical information by Printer, 10 characters/sec $65/month tracing graph with stylus $4-$5,000 Printer, 40 characters/sec $180/month Paper tape reader $60 /month The last three items in this list are under development Paper tape punch $88 / mon th and may be available by the time this report is avail- able. Also under development are translations of Tele- Card reader $70 /month Optical bar code reader $260 /month puter programs, developed for the Ramo-Wooldridge 288-1M Control unit (interface between RW400 computer, into the languages of some of the telephone line data set and the new time-sharing computers appearing on the market H-200 computer to handle one data (e.g., GE, CDC, IBM). As terminals of this sort develop station) $40 /Month and come into more widespread use, the number of hard- and software accessories can be expected to in- More complex control units are available to handle crease, along with the "performance per dollar" ratio.

33 6. HIM 2260`611T Displays 7. The IBM 1500 Instructional Station The 2260 is a 4" x 9" cathode ray tube display and just prior to press time, IBM announced there- buffer for alphanumeric text material. Charactersare stricted availability of a series 1500 InstructionalSys- repro tinted in a 5" X 7" dot matrix. The character set tem. Features of this system are described briefly tinder includes thirty-six alphanumeric, twenty-five special the discussion of the COURSEWRITER language in (including space and new lines), and three control Appendix A. The 1500 Instructional Station equip- characters. Transmissionisat 2,500 charactc,s/sec ment apparently is not designed for use independently when the display is directly connectedto the 2848 Dis- of the entire system. Since the relatively small IBM 1130 play Control by up to 2,000 feet of multiwire cable. computer is used as a central processing unit, thean- Truly remote operation requiresa communication nounced remote terminal equipment is intended for link between the computer anda remote 2848, using use within a few thousand cable feet of the computer. an adapter unit and data sets. Since the 2260 is alpha- A series 1500 Instructional Station (theremote ter- numeric only, a voice grade link is possibleover either minal) can consist ofsome combination of the follow- diaiable or leased lines, using 202or 201 series data ing devices. sets (up to 1,200 or 2,400 bits/sec, respectively). a. The 1510 instructional display with keyboard. The basic '2260 is $30/month, but it requires various This is a keyboard input-CRT output device sim- special features in order to be useful for mosttext dis- ilar to the IBM 2260 display unit. A completeset play problems. Vector generation (efficientconstruc- of alphanumeric characters with superscripts and tion of lines and curves on the CRT) isnot available subscripts, a cursor symbol, lightpen, and other on this equipment. features are available on the 1510. The alphanumeric keyboard is $20/month. b. The 1518 typewriter input-outputcan be used in The 2260 will display either 240 characters, 480 char- place of, or in addition to, the 1510 CRT display. acters, or 960 characters/station dependingon its c. The 1512 image projector is a cartridge film-strip adapter and 2848 control unit. projector controlled by thecomputer, with each The adapter will drive two 2260s and leasesas frame of the film individually addressable. follows: cl. An audio tape drive-play and the 1505 audio adapter permit the presentation of audio material 240 characters $40/month to the student, and also the recording of a recita- 480 characters $80 /month tion if desired. 960 characters $100/month Up to thirty-two remote stations, assembled from the The 2848 display controlt drives several 2260sas fol- units described above, may be connected througha lows: 1501 Station Control unit to the centralprocessor. The Station Control unit contains its own 24,576-wordcore 240 characters-24 stations $360/month storage and control circuitry for disk storage units. Be- 480 characters-16 stations $390 /month cause the 1500 Instructional System is to be made 960 characters-8 stations $420/month available only to selected researchgroups for develop- mental CAL work, no approximate pricesare avail- If more than two adaptersare needed, an expansion able. A complete system is alleged, however,to be unit at $45/month allowsup to six additional adapters. somewhat less expensive than the series 1400 COURSE- If hard copy is required, the unitsmay be adapted to WRITER system using IBM 1050 terminals. the 1053 printer for an added $10/month. Acursor feature (see glosrary, Appendix H)to facilitate editing 8. Raytheon DIDS-400 System adds $10/month, as does the capability of addressing This Digital Information Display System (DIDS) in- the display by line of text. cludes CRT, character generator, refreshmemory, and To simplify all of this, supposeone considers a re- power supply. Alphanumeric keyboard and hard copy mote installation of six 480-character 2260s with print-out are optional. With local buffering (storage), alphanumeric keyboards, cursors, and line addressing. up to 1,040 characters can be displayed in less than Such a terminal installation leases for about $1,055/ four seconds using a 2,400 bits/sec communication link. month or about $176/month/display. A movable cursor is provided foruse in indicating era-

34 sure and editing of data. The standard system displays punch, magnetic tape, or typewriter cost $200-$600/ forty characters per line, and either thirteen or twenty- month additional. six lines, with a display area of 61/2 x 81/2 ". The char- Each 1004 or 1005 system is interfaced to a data set acter set includes capital letters, digits, and twenty-six and a 2,000 or 2,400 hits /sec line by a device called a special symbols and punctuation marks. A computer- Dead Line Terminal, renting for $200-$290/month. telephone line control unit costs about $11,000, and the The data set at the computer end of the telephone line control unit between the terminal and the 2,400 bits/ connects to a Communication Terminal Module, tent- sec line, about $5,000. As usual, data sets (201 series) ing at $60-90/month depending on data rate. If several are required at each end of the telephone line. Up to terminals are used, up to sixteen of them may be con- ten display consoles can be located up to two thousand nected to the central computer through a multiplexing feet from the control unit. The console price varies Controller unit, costing $650/month, and up to sixty- from $4,000 to $6,000 depending on capability. A print- four terminals may be connected through more expen- er costs an additional $3,400. sive control units. These systems were designed for business applica- 9. The Control Data Corporation (CDC) 210 Com- tions and would require some modification to be suit- puter Inquiry and Retrieval System able for the typical scientific or instructional dialogue This is another system designed for business use, use. which is, however, potentially useful in CAL. Its basic unit is a 211 Entry-Display Station, consisting of a 11. Scientific Data Systems, Inc. (SDS) table top keyboard and CRT display. Twenty lines of The model 9437 keyboard-printer can be located re- fifty characters each may be displayed on the 6" x 8" motely from any SDS computer, using full duplex 2,400 screen, with the characters including the usual alpha- bits/sec transmission lines and a coupler (interface) numeric repertoire plus special characters to meet spe- which can accommodate up to three keyboard-printers. cific user needs. An index marker (cursor) can be con- This equipment is similar to the Teletype Model 35 trolled by the operator to correct mistakes and other. ASR, SDS also has a CRT display system with optional wise edit a message before it is transmitted to thecom- character generator, vector generator, and light pen. puter. A printer can be attached to the 211 station to provide hard copy of any information displayedon the 12. Sanders Associates Remote Terminal Devices CRT. Sanders Associates has just announced a new series Up to sixty-three display stations and forty printer of display systems incorporating alphanumeric key- stations may be connected to a 3290 Central Control boards and CRTs which display up to 1,000 characters Unit. This control unit is then connected to the cen- on a vertical 81/2" x 11" printed format. The model tral computer via 201 series data set, telephone line 710 is a basic information retrieval terminal; the 720 (2,400 bits/sec), and an interface unit appropriate to has a variety of editing capabilities; the 740 adds vec- the particular computer being used. tor capability and light pen. The latter would prob- Approximate costs of components of a 210 system are ably require wide-band communication links. as follows: Medium Data Rate Devices 211 Entry and Display Station $81 /month We shall rather arbitrarily define the medium data 3290 Inquiry and Retrieval Controller rate to extend from just above the maximum condi- for the 210 system $557/month tioned voice gra(,e line rate (roughly 3,000 to 4,000 218 Printer Output Station (IBM Selectric bits/sec) up through the lowest-frequency TELPAK typewriter, 15.5 characters/sec) $130/month serviceTELPAK A at 40,800 bits/sec. While some of the devices described below might operate at lower 10. UNIVAC 1004 and 1005 Systems rates, this is not usually desirable, because performance These units are actually small computers with arith- deteriorates too severely. Some of the medium rate metic and editing capabilities, and a small amount of applications are possible because of the use of a small core memory. Rental prices range from $1,150-$1,750/ computer at the terminal. Without such logic available month, with purchase prices from $46,000-$74,500. at the remote terminal, even higher-frequency data The adapter connections for peripheral card reader or links would be required.

35 1. IBM 2250 CRT Displays maintaining a flicker-free display of 15,000 points, 300 The IBM 2250 display is a versatile device that may inches of vector, or 1,000 characters ona 934" square include vector generation for graphic material, light area. pen, character generation, and a second keyboard for The PDP-8 allows a reduction in data transmission specially programmed display functions. This equip- because programming allows one to transmit changes ment must operate with its 2840 control unit close to in the display rather than entire pictures. Rotations of the central facility. The 2250 may be located up to the display may be done at the terminal', again reduc- 2,000 cable feet from the 2840. A special featuremay be ing the amount of data to be transferred. These fea- obtained to allow the 2840 to he locatedup to one mile tures allow satisfactory operation with voice grade data from the central computer, usinga long line adapter links. and a 125 KHz bandwidth line. No area price is avail- DEC prefers to sell its display at an approximate able at present for this feature. Distancesover one mile price of $50,000. However, leasing arrangementscan are under consideration. be made at about $1,250-$1,500/month, depending Common carrier links are also under consideration. upon actual equipment selected and negotiation with However, at 2,400 bits/sec using voice grade lines and the company. 201 series data sets, it is not likely that light pen track- 3. Philco READ System ing can be achieved. For this, wide-band service of at The Real-time Electronic Access Display system least TELPAK A (40.8 KHz) and very likely TELPAK (READ) is a CRT, keyboard, and light pen capable of D (up to 1 MHz) may be required. (These facilitiesare textual, tabular, and annotated graphical formats. In- described more fully in Section III of this appendix.) formation can be viewed directly on the face of the The 2250 display for a single unit witha full comple- CRT, projected on a wall screen, recorded on 16 or 35 ment of graphical features may be estimated as follows: mm film, or reproduced on paper by a Xerox recorder. 2250 Display Unit $350/month It displays over 4,000 characters or 2,000 lines which Absolute Vectors $225/month are refreshed thirty times per second. Screen sizes are Alphanumeric Keyboard $ 50/month available from 9" to 24". Characters can be defined by 8K Buffer Storage Unit $400/month the user. Character Generator $300/month 4. Control Data Corporation Digigraphic System Light Pen $ 75 /month 270 Programmed Function Keyboard $100/month The CDC Digigraphic System is a light pen console $1500/month system which is actua!!y designed for use within a few 2840 Control Unit (up to three 2250s hundred feet of a CDC 3200 computer. In this sense, it using a multiplexor) $1100/month is not a true "remote" terminal system, although it may Vector Control Unit $ 125/month be possible to modify the CDC system to permit linking $2725/month of the consoles to the control unit or the control unit to the computer by wide-band communication lines. Hence, three such 2250 units sharingthe same 2840 The 273 Digigraphic console contains a 22-inch would lease for $5725/month. diameter CRT, a light pen, and a 25-key keyboard. By suitably programming the computer, the keys are as- 2. Digital Equipment Corporation 338 Display signed to perform specific, frequently-required func- The DEC 338 display is an interesting device because tions. The surface of the CRT is divided into a work- it indicates how one may obtain significant gains ing surface-an 11" X 17" or 14" X 14" rectangle-and through the use of a small general-purpose computer a control surface, defined as the area outside the work- as an integral part of the terminal. In this case, the ing surface. Graphic displays are formed and the light PDP-8 computer is used with the DEC 340 display to pen is used to enter graphic information within the provide an economical, flexible graphic display with working surface. Light buttons,3 light registers,4 and modest communication link requirements. Light buttons function in much the same way as programmed keys on the This combination of equipment is able to perform keyboard, except that they are "depressed" and their programs initiated with display computations with a 1.6 microsecond cycle the light pen rather than with the finger. 4 Light registers permit the user to enter certain special kinds of alphanumeric time to achieve a rate of 300,000 additions/sec while information into the computer by writing with the light pen.

36 alphanumeric information can be displayed on the operations on an oscilloscope for the purpose of in- control surface. structing a student in how to use such an instrument. The basic function of the Digigraphic System is to A laboratory experiment which requires an isolated permit graphic communication between man and ma- environment could be carried out by means of a pro- chine. The user can enter information into the com- cess controller, eliminating possible hazards or dis- puter by sketching or by specifying end points of lines, turbing influences from direct manipulation of the vertices of polygons, centers and radii of circles, etc., apparatus. At a more advanced level, such equipment with the light pen. He can then cause the computer to would also make it possible for students to gain expe- operate on this information in a programmed way and rience in sophisticated techniques of equipmentcon- display the results. trol and data analysis. A standard 270 Digigraphic System consists of a 271 To provide a general idea of what process control Controller Unit, a 275 Gruffer memory, and one 273 terminals do and how much they cost, a few examples console, all leasing for $5,500/month. Up to three 273 are described below. consoles can be used in each system, each located up to 200 feet from the 271 Controller. The CDC 3200 com- 1. IBM 1070 Process Communication System puter,amedium-size, general-purpose computer This terminal system is designed to provide a means which is a necessary part of the 270 Digigraphic System for carrying out laboratory experiments under the con- and which may be time-shared, leases for $10,000- trol of the central computing facility at fairly low cost. 512,000 /month. !n addition to the 1070 system configuration designed to meet particular laboratory needs, this equipment High Data Rate Devices requires a voice grade line (an ordinary telephone cir- These devices require very expensive transmission cuit is adequate) and data set. lines even for short distances. If real-time direct trans- There are two models available with the ability to finr is required, multiple TELPAK lines may be em- provide two different rates of data transmission. The ployed. For very large bandwidth, microwave circuits 1071-2 terminal control unit operates at 66.6 charac- may be used. In most cases, however, it is far more eco- ters/sec and leases for $170/month. The 1071-2 also nomical to use a small computer buffer. requires a more expensive data set (202 series at $40/ Devices falling in this category are: month). Studies are being conducted to determine whether Direct drive cwr displays; the 1071-1 may use the same data set as the 1050, but Core-to-core transfers; the price range is essentially correct if one assumes the High performance magnetic tape; 103 series data set at $25/month. Intermediate storage to and from core; The 1071 may be attached to a variety of devices High-speed analog-to-digital and digital-to-analog such as: equipment. 1072 Multiplexor and Terminal Unit. Devices in this category typically operate from 50,000 (Provides terminal pasts and switching bits/secupward. Common carrier communication relays for up to fifty process signals. Up channels in this bandwidth are available up to and to six 1072s may be combined in one including the 10 MHz used for color television. terminal station.) $10/month 1073 Terminal Unit (controls opening and Process Communication and Control Devices closing of up to fifty switches to operate These devices are used for such purposes as control- laboratory devices). $15/month ling a laboratory or manufacturing process, feeding in- 1074 Binary Display (ten light pairs). $30/month formation into the process and/or extracting data from 1075 Digital Display (up to eight digits). $60/month it, analyzing the data, and feeding it back and/or dis- 1076 Manual Binary Input (ten on/off playing the results. Such equipment probably will not switches to signal process be as useful for instructional purposes as that described information). $25/month above, but it may have some applications to under- 1077 Manual Decimal Input (six ten- graduate laboratory situations. For instance, a process position rotary switches to enter controller might be used to program a sequence of decimal data values). $25/month

37 1053 Alphanumeric Printer (to print Because of the extreme versatility of the equipment, output and display operator complete 1800 systems can be configured ina large instructions). $50/month number of ways. This unusual flexibility makes it diffi- 1071 Analog-Digital Conversion. (Converts cult to give realistic area prices fora system. Several high level analog voltages [-1 to +5 volts study configurations indicate that a fairly sophisti- full scale] to three BCD [binary-coded cated terminal will lease for $3,000-$5,000/month. As decimal] character representations for an example, the following system was configured at transmission to central facility. Conversion about $3,000/month: time is 16.7 milliseconds/sample.) $65 /month Paper tape I/O; Other features available include thermocouple ref- Keyboard-printer; erence blocks, digital pulse converters, digital pulse 2315 disk storage unit (for data logging); counters, and many other similar devices. Interface with IBM system/360 central computer; Consideration is being given to featuresto allow 96 bits of digital voltage level input; keyboard-printer and digital -to- analog conversion. 80 bits of digital pulse output; Without a keyboard, some independentway must be 32 points of analog input with comparator and -4-10 used to alert the central computing facility thata 1070 mV, +50 mV, and ± 200 mV amplifiers,as well station wishes to log on. As mentioned earlier,a touch- as high-level inputs; tone telephone might suffice. 16 process interrupts (terminals through which Because the terminal configuration isso dependent switching signals from the processcan be fed into upon the needs of a particular experiment or process, the control unit); it is almost impossible to giveaccurate general price 8K-four microsecond process controller unit. estimates. However, a rather minimal terminalmay be estimated at about $250/month,a fairly sophisticated 3. DEC PDP-8 Process Control Terminal System terminal at $550/month, anda fairly typical experi- The versatile, relatively low-cost PDP-8 isa nu- ment setup at $350/month. cleus around which one may construct a flexible lab- The use of this equipment would allow lowdata oratory terminal. The basic PDP-8 consists of a 4096 rate instrumentation of many experiments in which twelve-bit word memory, console, typewriter,paper the logical power of the central computing facilitymay tape reader and punch, and I/O console. To this one be applied. Datamay be collected and analyzed, and may add A-D converters, digital contact sensing and the computer may initiate actionsto manipulate and operation systems, data set linkage, D-Aconverters, control the experiment. and so on, to form the desired laboratory terminal. 2. IBM 1800 Data Acquisition and Control System Once again, it is difficult to estimate the system cost in general. The basic PDP-8 sells for $18,000, and sample This is a versatile laboratory terminal with the logi- system studies indicate a total system terminal with cal capability of a small computer anda wide variety capacity for: of digital input and output terminals,analog-to-digi- Data set communication with central facility, tal (A-D) and analog terminals, andmany other valu- 12 independently-buffered D-A conversions (11 bit able features for conducting experimentsrequiring plus sign), more precision and higher data acquisition rates than 12 multiplexed A-D conversions (11 bit plus sign), are possible with the 1070. In addition,a variety of 96 relay contact interrogations, and peripheral equipment is available for datalogging and 96 relay contact outputs display at the terminal location. Wide-bandcommuni- at a price of about $54,000. While DEC prefers not to cation lines are necessary to link thissystem with a lease, an approxiinate figure of $1,200/month is es- large central computer. timated:"..1/4Maintenance charges are $200/month. In The 1800 Process Controller unit is available with addition, a wide-band communication link witha either two or four microsecondmemory in sizes from central computer is necessary. 8K (8,000) to 64K (64,000) bytes (eight-bit words). The It is to be emphasized that the use of a small com- lease price for the 8K-four microsecond machineis puter as a part of the terminal is essential in many $1,165/month, while the .64K-two microsecondma- laboratory situations. By having the computer actas a chine is $3,250/month. digital filter as well as a process controller, it ispos-

38 sible to reduce the requirements for communication it has been difficult to insure that devices and facilities channels to the central facility to more reasonable with identical features and capabilities are being com- levels. The inherent advantages of central facility sup- pared. The companies themselves must be contacted port for the laboratory experiment is retained and en- for official, up-to-date cost and information. hanced in this way. The central facility functions in the most vital role of analysis and overall control, with Teletype and Voice Grade Lines the terminal able to execute these commands on site. This category of communication service may be sub- III. COMMUNICATION LINKS classified into circuits which are limited to reliable data rates of less than 2,000 bits/sec (the ordinary tele- After having determined the terminal needs, the next type and telephone services), and those which permit problem is the transmission of data to the central reliable data transmission at rates up to 3,000 bits/sec facility from the terminal, and the receipt of signals or so (Broadband Exchange Service and specially con- from the central facility to control the terminal de- ditioned leased lines). In particular, communication vices. As indicated earlier, this transmission may take, links in this lattegroup are necessary for the many place at a variety of data rates. The lowest-cost com- terminal devices which require data transmission at munication links are those with relatively low data 2,400 bits/see. rates, and are classified as voice grade or teletype In general, leased private lines are more reliable service. Such service is limited to data rates of less than than dialable circuits, because they are conditioned and 3,000 bits/sec or so and includes the various kinds of guaranteed to provide a certain level of service. How- ordinary telephone and teletype service, plus private ever, those dialable or switched circuits designed for leased-line facilities and Western Union's Broadband data transmission may be more satisfactory in this Exchange Service (BXS). This latter service is (or will respect than telephone lines, which are intended for soon be) capable of transmission rates in excess of a voice communication. Western Union's Broadband few thousand bits/sec. For data rates up to 106 bits/sec, Exchange Service, for instance, employs a combina- wide-band TELPAK leased lines seem to be the only tion of four-wire circuits for short distances and micro- common carrier service available. wave relay transmission over long distances, and has Just as computers and terminal devices are under- been engineered to minimize noise, crosstalk, and dis- going development causing a very fluid price structure, tortion which interfere with reliable data transmission. so communication lines and data sets are being im- Nevertheless, several of the terminals described in Sec- proved at a rapid pace. The cost figures quoted in this tion II above can and do operate satisfactorily over or- section were applicable to The University of Michigan dinary telephone circuits. Sometimes the particular cir- and southeastern Michigan as of the spring of 1966. cuit obtained by dialing may happen to be noisy, And just as computer engineers must be consulted in preventing reliable transmission. In such cases, the the design of remote terminal systems and central com- computer may be dialed repeatedly until a noise-free puting facilities, communications engineers from the circuit is obtained, and charges for the noisy connec- telephone company or Western Union must be con- tions may be deleted by the telephone operator. sulted to obtain an efficient and effective design and accurate cost information for communication links. 1. Teletype and Voice Grade Circuits Limited to The truth of these warnings has been indelibly im- Data Rates Less Than 2,000 bits /sec pressed upon those of us involved in collecting infor- Of the five kinds of service described in this category, mation for this appendix, and for the sectionon the first two (teletype exchange and telephone services) communication links in particular. involve message charges based on the number and However, the prices mentioned in this section should length of messages. Since the other services described provide the reader with a general idea of the amount (private wire teletype, WATS, and foreign exchange) of money involved in tying a terminal to a computer do not require message charges, any comparison of located some distance away. In cases where the rates costs must take into account the amount and type of of two common carriers (AT&T and Western Union) use. If very heavy use is to be made of the communica- are compared, any differences may be temporary or tion link, for instance, the teletype exchange service, apparent, rather than real. Fast developing technology which appears to be the least expensive of the five has caused rates to change rapidly, and in many cases services described, could turn out to be considerably

89 more costly than the most expensive wide area tele- for the instrument are, of course, extra. For example, phone service. the touchtone feature mentioned in Section II costs an additional $1.00/month. If the data set is to be a. Teletype exchange services placed on an extension of an existing line, the exten- If teletypewriters are used as terminals, one of the sion is $3.50/month. But in this case, an exclusion fea- dialable teletype exchange services may be used at ture at $.25/month is required to prevent interference lower cost than ordinary telephone service. The nation- in data transmission from the other telephone. wide TWX (AT&T) and Telex (Western Union) net- If it is not possible to install a telephone within a works can be used in much the same fashion as the Centrex system, the facility may be installed ona busi- long distance telephone network. Voice communica- ness phone, which rents at a basic price of $9.05/month tion between the remote user and the computer is not in Ann Arbor, Michigan. possible over these networks. Although the data rate As with ordinary business telephones, local data is low, this may not be a serious disadvantage in connections are available without limit at the standard many instructional or research situations. monthly charge, and long distance data connections In the Telex service, the rate for a oneminute mes- cost the same as long distance telephone calls. Because sage between Ann Arbor and New York City is $.30. of the message charge, extensive use of the long dis- There is no minimum message length, and there is a tance telephone network can be expensive. 40% discount on monthly charges in excess of $87.50. AT&T's TWX service assesses charges on the same c. Private wire leased teleprinter lines basis as long distance telephone calls. The rates are In a low data rate system involving heavy traffic be- somewhat lower than long distance rates, but the tween fixed locations, a leased teletype line may be minimum threeminute message is charged for and more economical than exchange service with its mes- there is no quantity discount. Therefore, in some sage charges. Such lines may be leased from AT&T or cases TWX may be more expensive than Telex. Western Union at identical rates. The basic interstate However, an accurate comparison of costs again re- mileage charge for leased teletype lines is $1.10/mile/ quires a careful investigation of the kind of use to be month for the first 250 miles, decreasing in three steps made of the communications facilities. to $.385/mile/month for distances beyond 1,000 miles. Intrastate rates vary from state to state, but in Michi- b. Local telephone service gan they run about twice the interstate rate. Basic line charges in The University of Michigan The basic line will carry up to 56 bits/sec from a Centrex system are $8.75/month fora line to the standard 75 words/min (wpm) teletypewriter operat- central office, including a telephone. Special features ing with a fivelevel character code (five information

PRIVATE WIRE LEASED TELEPRINTER LINES COSTS PER MONTH HALF DUPLEX 150 bits/sec 45 and 56 bits/sec 75 bits/sec (ASCII code, FULL (5level code, (5level code, 100 wpm, and DUPLEX 60 and 70 wpm) 100 wpm) IBM 1050) Line cost, 1st 250 mi $ 1.10/mi $ 1.21/mi $ 1.375/mi Add 10% over 1000 mi 0.385/mi 0.424/mi 0.481/mi Add 10% Channel termination' 12.50 13.75 15.625 Add 10% Local circuit' 6.70 7.37 8.375 Multiply by 2

These charges apply at each end of the line.

40 4

bits plus one. start and 1.4stop bits/character). Condi- (ii) Interstate WATS service from tioning the line for 100wpm in the fivelevel character Ann Arbor. code (75 bits/sec) adds 10%to the cost. Private lines Zone 4 (extending fromeast coast conditioned for 150 bits/sec have recentlybecome to rocky mountain states, ex- available, as a standard item, and lease for 25% more cept Florida and Michigan) $1,400 /month' than the basic linerate quoted above. Such lines will Zone 6(continental United States handle the 110 bits/sec rate of Model 33 and 35 tele- except Michigan ) $2,050/month° typewriters using the ASCII codeat 100 WPM, as well as the 14.8 characters/sec rate of the IBM 1050ter- A recently-developed modification of WATS isIN- minals used in the COURSEWRITERsystem. An ad- WATS, which permits a subscriberto receive incoming ditional 10% is added for fullduplex facilities, calls from a specified geographicalarea at a flat permitting simultaneous sendandreceive. monthly rate. This service isnot yet available on a To these line chargesmust be added channel ter- nationwide basis, although it probably willbe in the mination and local circuit chargesat each end of the near future. The charges are thesame as those for line. These, together with theline costs described WATS. above, are summarized in the table on p. 40. e. Foreign exchange service d. Wide area telephone service (WATS) This type of service in effect places theuser's tele- Wide area telephone service permits theuser to dial phone in a remotelylocated exchangearea. For in- any telephone or computer installation withina spec- stance,if extensive communicationwere required ified area for a flat monthly rental.The rates quoted between the Commisionon College Physics office in here for this serviceare those for a user in Ann Arbor, Ann Arbor and various telephonesand computer Michigan, and are given merelyto provide a rough installations in the metropolitan Detroitarea, then idea of the costs involved. foreign exchange service would permitCCP to dial as (i) Intrastate WATS service charges. if its telephone were located in Detroit ratherthan in Entire state of Michigan (Area Ann Arbor. Data connectionsto installations in the codes 313, 517, 616, 906) $700/month Detroit exchange area would be availablewithout Eastern lower peninsula (Area limit at a flat monthly rate. BetweenAnn Arbor and codes 313, 517) $400/month Detroit (a distance of about forty miles), thisservice Southeastern Michigan (Area would cost $163/month. Foreign exchange servicebe- code 313) $300/month tween Ann Arbor and New York City (a distance of

WESTERN UNION PWS AT&T Half Full Half Full Duplex Duplex Duplex Duplex Mileage rate interstate $ 2.02 $ 2.22 $ 2.02 $ 2.22 Mileage rate intrastate No tariffs filed; 4.25 4.68 about same as AT&T Channel termination charge" 12.50 13.75 12.50' 13.75 Local circuit charge" 10.00 18.25 12.50`l 13.75 Conditioning charge. 1,200 bits/sec 20.00 20.00 None None 2,400 bits/sec 47.50 47.50 37.50 37.50 " In Michigan. " Applies to each end of communicationline. Total cost for a system is therefore twice thefigure given. e Includes high -level transmission filters and driveramplifiers. '' For lines over 25 miles in length.Cost is $7.50/ month plus $5.00/ month/ additional stationon circuits shorter than 25 miles.

5 or (5415 $24/hr for each hour over 15 hrs)/month 6 or ($540 $30.50/hr for each hour over 15 hrs)/month

41 r

515 miles), costs about $980/month. This service is Typical metered line charges for BXS are, per generally less expensive than WATS, but more costly minute, than a pointtopoint leased line, reflecting the fact 2 KHz Service 4 KHz Service that it is intermediate in scope and flexibility between DetroitNew York $.30 $.35 these other services. DetroitLos Angeles .55 .65 Between any two 2. Voice Grade Circuits for Data Rates up to about points in Michigan .20 3,000 bits /sec A minimum usage charge for one minute applies on a. Private leased lines each completed call or data connection. Beyond the Leased lines are pointtopoint, telephonetotele- first minute, fractional minutes are charged for in phone, or switchboardtoswitchboard connections, al- tenths of minutes. These rates apply within the limits ways at the disposal of the user. The significant of cities with Class I Western Union telegraph offices advantage they posses over dialable circuits is that (this includes most cities of over 25,000 'population). PWS (private wire service) lines must be leased to bandwidth and freedom from noise can be guaranteed by the leasor. serve any locations outside of such cities. In addition to the line charges, there are certain nonrecurrent If several voice grade channels are used extensively and monthly charges for the communications equip- between two points, it may be economical to lease a wideband line for multichannel voice grade trans- ment required to use BXS. These are summarized in mission. A 48 KHz TELPAK A line, for example, the table below. can carry twelve 2,400 bits/sec full voice grade chan- 3. Data Sets for Voice Grade Service nels (see the section on wideband facilities below). The data sets to be used with common carrier lines The monthly cost of a private line leased from depend for their designation upon whether the line Western Union or AT&T can be estimated from the is a dialable line or a leased line, and whether the table on p. 41. code is presented in serial or parallel fashion. The b. Western Union Broadband Exchange Service (BXS) Fixed Western Union has developed a flexible and versa- Non- monthly tile switched circuit system for data transmission called recurringservice and the Broadband Exchange Service. BXS subscribers can installationequipment dial other stations in their system in the same way charge charges they use the long distance telephone; they can also Broadband service (including dial the class of service (data rate) they need for a local channel facility, particular purpose. Line charges are billed on the telephone instrument, and basis of duration and distance of call, and class of association subset): service selected. At present, customers may subscribe Schedule I service (2 KHz) $25.00 $15.00 to Schedule I service (so-called 2KHz service), and to Schedule II service (4 KHz Schedule II service (4 KHz or 2 KHz service, selected and 2 KHz) 25.00 30.00 by the user for each call). The 2 KHz bandwidth ac- Data set (for modulation/de- commodates a data rate of 600 bits/sec, while 1,200 modulation of signals, and 2,400 bits/sec require the 4 KHz bandwidth. It is serial bit-by-bit transmission): anticipated that bandwidths of 8KHz, 16 KHz, and Schedule I service 0-600 bits/sec, asynchronous 25.00 27.00 48 KHz will be added in the near future. BXS provides Schedule II service full duplex (simultaneous send and receive) facilities 0-1,200 bits/sec, asynchronous 25.00 27.00 at all data rates, and permits users either to communi- 0-2,400 bits/sec, asynchronous 50.00 42.00 cate by voice or to transmit and receive data in digital 2,400 bits/sec, synchronous 50.00 72.00 or analog form. The system is designed with four Circuit extensions beyOnd city wire circuits and special switching gear to minimize limits: the noise, distortion, and crosstalk which can inter- Channel conditioning charge 10.00 10.00 fere with reliable data transmission. Rate per mile . 2.22

42 '7 "7"911P7,11.F"

following table is a summary of the most popular Bell TELPAK A service between Ann Arbor and New York System data sets likely to 'be found in voice grade City, for instance, would cost $7,725/month. With the service at the central facility. Prices of theseare fairly possible exception of TELPAK A, these linesare us- stable, but new kinds of data setsare currently being ually engineered to meet the special needs of theuser. developed, especially for use with large centralcom- Therefore, the rates are only approximate. puting facilities. Prices of Western Union datasets are comparable, as may be seen from the above table of 2. Data Sets for Wide-Band Transmission charges for BXS equipment. With the exception of TELPAK A service, data sets for wide-band transmission are special devices de- Data Set Series Data Rate Lease Price signed for a particular purpose. For TELPAK Aserv- (bits/sec) ice, the 301 series data sets are available to operate at 101, 105 110 $25/month 40.8 kilocycles synchronous transmission rate. These 103 134.5 $25/month 202 0-1,200 $40/month devices rent for $250 /month, andone such device is 201 2,000 or 2,400 $70/month required at each end of the TELPAK A line. (synchronous) The data sets for TELPAK B, C, and D servicere- quire engineering design for each application. How- WideBand Transmission Facilities ever, order of magnitude estimates may be given for Wide-band facilities are those permitting datarates TELPAK C data sets at $550/month/terminal, and for greater than 3,000 or 4,000 bits/sec. Although Western TELPAK D data sets at about $1,300/month/terminal. Union's Broadband Exchange Service described above There are, obviously, some applications which can may soon become available at these higher data rates, only be served adequately through wide-band facili- the only services now commercially availableare the ties. But the foregoing should indicate the importance TELPAK facilities. These can be leased from AT&T of careful study of each application in order to realize or Western Union at identical mileage rates. Facilities the most economical trade between bandwidth and the exist to transmit signals witha bandwidth (data rate) logical capability of the terminal device. As indicated greater than the 1 MHz of the highest grade TELPAK earlier, the use of a small computer at the terminal service. However, these video bandwidth channels may frequently reduce the bandwidth requirements of are so expensive and so unlikely to find application the communication line to voice grade service, where to CAL in the immediate future that they willnot be otherwise wide-band facilities would be required. discussed here. IV. THE VIDEOFILE7 SYSTEM In addition to the line rental and data setcosts described below, there will be various charges for The development of video tape recorders has made channel terminations and necessary local facilities and it possible to devise automated systems for the storage, circuits at either end of the TELPAK line. Since these retrieval, display, and duplication of printed matter will depend on the particular application, andsince and other documents using magnetic tape. The only the mileage and data setcosts usually will be very system of this kind on the market at present is the much larger, no attempt has been madeto summarize elaborate and highly flexible Videofile system made these additional items. by the Ampex Corporation. Videofile units could be included in a CAL network to display visual informa- 1. Line Rental Charges tion to the student, accomplishing thesame function At the present time, four grades of TELPAKservice as the automatic slide projectors mounted in modified are available as shown in the following table. IBM 1050 terminals. Briefly, the Videofile system enablesa document or Bandwidth Interstate microfilm frame to be recorded on magnetic tape along (or data rate Rate/Mile/ with an identification code. The tape thencan be Service in bits/sec) Month scanned automatically to find any given stored docu- A 48 KHz $15 ment by feeding the appropriate code into the system. B 96 KHz $20 Requests for a document can be made from a localor C 240 KHz $25 remote station with a telephone dial, a keyboard, or a D 1 MHz $45 7 Trade Mark, Ampex Corporation

43 card reader, or by a central computer. Typically, formed from top to bottom of thescreen, so that if 259,200 documents originally 81/2" x 11" can be stored text is involved, the student can begin reading before on a fourteen-inch diameter, 7,200-foot reel of two- the image is completely formed.) The Videofilesystem inch magnetic tape; the average access time to retrieve can be time-shared just as is the central computer. any of these documents from the tape is 115 seconds. A second possibility is to locate the Videofile unit in (For a five-inch reel of tape holding 10,800pages, the a classroom building housing many instructional average access time is only eleven seconds.) Images are terminals and remote from the central computer. Re- recorded on the tape from a video cameraor a micro- quests for visual information can be transmitted from film attachment, and may be displayedas a refreshed the instructional program in the computerover a voice TV image on a CRT or printed on a facsimile device. grade line to the Videofile. TV pictures from the The usual CRT-TV display requiresa wide-band, video tape recorder can then be distributedover inex- coaxial transmission line between the tape unit and pensive runs of coaxial cable to the appropriate nearby the display station, whereas the facsimile reproducer instructional terminal. Such an arrangement would be can operate over voice grade telephone lines. Slow- economical only when a large number of remote termi- scan television transmission can also be used to trans- nals could be located near each other andnear the 'mit an image over voice grade lines toa CRT station Videofile system. at a rate of 80 sec/page. A basic Videofile system designed for a particular There are at least two ways in which Videofile could purpose can be purchased for about $200,000-a very be incorporated into a CAL system involving remote approximate price. The system as it now exists, how- terminals without requiring wide-band transmission ever, is probably larger, more flexible, and perhaps facilities. A Videofile system located at the site of the more sophisticated than necessary for use with CAL. central computer could send images of documents As the systems come into more widespread use, as tech- (graphs, text, illustrations, etc.)to the appropriate nological improvements are made, and as other manu- remote terminals upon request from the instructional facturers enter the field, prices will probably decrease program stored in the computer. The image of the substantially. The Ampex Corporation is currently document would appear on a CRT at the remote ter- developing smaller, less expensive versions of their minal as a slow-scan TV picture. (The picture is system.

44 appendixc

Linguistic Mode Physics Programs

The programs described here are representative of physical situation, by reference to the text, by suggest- physics programs prepared to date for use in an in- ing that the student work another problem first, or, in structional format, Most were prepared in Seattle dur- unusual cases, by supplying a needed piece of informa- ing summer of 1965 at the Working Conference on tion. New Instructional Materials held at the University of Computer assistance on the lab is designed to help Washington, and all were programmed in IBM's students perform the experiments, should they feel COURSEWRITER language. Although several have they need help, and to reinforce them, should they not yet been debugged and none have been rigorously need assurance that what they have done is correct. tested, these programs nevertheless indicate some of The examination is divided into three parts. Part I the ways physicists have attempted to use the computer involves the construction of a piece of optical appara- as a teaching tool within the present course structure. tus and the measurement of its properties. The student We emphasize here that these materials are at best first is given a kit of lenses, etc., and an optical bench. He efforts which may guide others seeking to develop new is told to build an instrument (six different versions auxiliary tools for physics teaching. of Part I have been prepared) that meets certain speci- fications (for example, a noninverting "projector" GEOMETRICAL OPTICS UNIT consisting of two lenses, such that the objectto (T. R. PalfreyVictor CookRobert Dough projectedimage distance be the length of the optical Michael Brady) bench, and the objecttosecondlens distance be as short as possible). He is asked to measure properties of This is a selftaught instructional unit (i.e., no in- the finished device. When he has measured the sug- structor is available to the student for this material) gested parameters, he signs onto the terminal and an- prepared for use at Stony Brook during spring 1966. swers questions about the device he has built. The It consists of assistance on problems and laboratory terminal may accept his answers, or may decide that work and an examination, of which only the examina- his measurements were too sloppy, or that his device tion is required of the student. Help on problems and could not have worked as specified. Instructions and laboratory work is optional. The work is keyed to hints from the terminal then guide the student (at a Chapters 26 and 27 of The Feynman Lectures on cost in examination score) toward a good design. When Physics, Volume I. the design and measurements meet the standards re- In working problems, the student requests help by quired, the student proceeds to Part II of the exam. problem number and is interrogated by the computer. Part II consists of one or two questions designed to He may be asked if he has read the appropriate sec- find out if the student either understands the function- tions of the text; he may be asked about definitions, ing of the device he has built, or can figure it out. sign conventions, or about his results for parts of the These are ordinary pencil and paper problems. For problem. The terminal will normally provide help in each Part I there are three alternative Part IIs. The the following forms: by presenting a slide sketch of the possibility exists that the student could report his

45 results on Part II to the terminal, which could then the names of the interactions and the order of their grade his remit. strengths; requires no quantitative knowledge. Part III, of which about six versions are planned, e5 will consist of one or two mere conventional questions. At least one of the problems will probably involve Asks for the numerical values of ten widely used application of Fermat's principle, which is empha- physical constants, accepting allresponses that are sized in Feynman. correct to two significant figures. Scores the student and sends him back if less than fiveare correct. DEMO --2 (Everett M. Hafner) begin This program was written for the IBM 1440 using A problem in elementary mechanics, dealing with forces and torques on terminals in Ann Arbor and Seattle. Its central idea is an accelerating rigid body. the introduction of a variety of topics in physics, at Seeks the condition for whicha tipped cube, sliding different levels of difficulty, using the style ofan oral with friction on one edge, does not rotate. Students exam. The aim is not to teach the subject, but to frequently make the error of assuming thattorques can be taken about an edge; when they do, they are reveal quickly a student's range of knowledge,grasp of fundamentals, and ability to deal with unusual led to see that the result is unreasonable, andare problems. We list below the principal labels of denio- then guided through a correct treatment. 2, with brief descriptions of the material under each timing label. Deals with transformation of the Coulomb force start to a moving coordinate system, and reveals a rela- First label. Gives the option of transferring either tivistic discrepancy between what appears to bea to "instructor" or to "student." correct result and the general law for transformation of forces. Asks the student to identify thesource of instructor the discrepancy. Describes material and reveals principal labels, The sample also contains, under the label "writer,"a thus providing the option of beginning atany of guessing game for COURSEWRITER authors. One several points. discovers the flow of a program by guessing and trying student a set of "ca" and "wa" statements. The game is de- Explains that material will be presented inse- signed to give rapid experience with the logic of quence, but that any topic may be skipped. Does COURSEWRITER op codes. not reveal labels. Comment exh2 Raises the question of the time required for a Each part of demo-2 is an attempt to explore a particle to fall torr.z ,h from the distance of the special direction along which programmed testscan moon. Leads the stuti...iit to the order of magnitude, go. Thus, the problem in Kepler's Laws probes a and then to a good calculation from Kepler's Third student's intuition; the quiz on terminology tests his Law. An interesting feature of this question is that familiarity with names, while the list of constants tries the correct answer can be obtained by an en- his knowledge of numbers and units; the mechanics tirely wrong method involving two comps _sating problem exposes a common misunderstanding of rigid errors: taking the period to be equal to the calendar body motion; and the relativity dialogue isan attempt month, and assuming that the average speed of fall to raise, without completely answering, a provocative is equal to the orbital speed. Discusses the accuracy question which he may wish to pursue further. The of the correct method, and tests the student's mastery model on which the sample is based is the typical quali- of the method by raising similar questions about fying oral exam, in which these aspects ofa student's planetary orbits. approach to physics come under scrutiny. Passing quickly from topic to topic, we attempt to evaluate his exhl entire state of knowledge on the basis ofvery little A brief quiz on the fundamental interactions and evidence. the classes of strongly interacting particles. Asks for Even from this limited point of view, the sample in

46 zir-11,7-1Pnr7r ,7-7,74,,T77TrimAnr. -117=1-711111

.101

its current form needs improvement. Especiallyin the 8a. Draw some graphs. Is it clear? mechanics problem, where the need for matching for- (yes) br 8b mulas is inevitable, students bog down in symbolic (no) suggest sign off. difficulties that have no bearingon their knowledge 8b. Example of differentiation ofx(t). of physics. Since littleattempt is made to time and (right) br 8c score the student within the program, his workmust (wrong) suggest sign off. be read by an instructor. Weare hard on the man 8c. Average velocity in example; br8d or sign whose approach to things isvery different from ours. off. And the value of some of the material, forpurposes of 8d. What is t(i) in example? br 9or sign off. testing, dependson its novelty. In order to be of any 9. Is there a t such thatv is same for both particles? use, the test would have to contain muchmore mate- (yes) Perhaps you guessed. br 10 rial, selecting at random theset that each student en- (no) br 9a counters. 9a. Do you understand? br 10or br 9b. "VEL" 9b. Clarification. br 10or sign off. (Everett M. Hafner) 10. Number of intersections in (x, t). 11. Concept of derivative. The label "vel" undercourse Seattle 2 in the 1440 CAI system is a brief diagnostic exercise (right) br 12 on the concept (wrong) br Ila of instantaneous velocity. It seeksto discover, through 1 la. Clarification. br 12 a sequence of increasingly difficult questions, thestatus or sign off. of a student's understanding of theconcept. Principal 12. Do u(t) and v(t) intersect at t, and t2? points and branches in the flow diagramare as follows: 13. What must they do? 1. Write a definition. (The 14. Let's prove that they intersect. Whatabout dis- program does not exam- tances? ine this response; it is for informationonly.) 2. If we know (x t1) and (x2, t2) for 15. Common property of thetwo velocity graphs. a particle in (right) br 16 motion on x, do we know v(t)or v(t2)? (no) br 3 (wrong) br 15a; clarification and br 16 (yes) br 2a 16. So what must the curves do? (right) br 17 2a. Would we know v(t,) ifv were constant? (yes) br (unclear) br 16a; clarification; br 16or sign off. (no) br 2aa 17. What about the accelerations? 2aa. Numerical example ofaverage velocity. 18. Is there an x such that v(t) is thesame for both (right) br 2 particles? (wrong) suggest sign off. 19. Proof. 3. If we know (x t1), (x,, t2) andv(t,), do we know v(t2)? Comment (no) br 4 1. The prograd contains (yes) br 3a many parts which pro- ceed independently ofresponse. Also, it does not 3a. Special case; br 2or sign off. incorporate scoring mechanis . 4. Concept of average velocity. Therefore, it is only useful if the studentrecoi d is examined by (right) br 5 an instructor. (wrong) Case of uniform motion; br 5or sign 2. The emphasis of the program is off. on a working knowledge of concepts, not on ormal definition. 5. Upper and lower bounds on v(t). In a more satisfactory version,a nicer balance 6. Do we know v at midpoint of time interval? would have to be establishedetween these two 7. Mean value theorem. aspects of the subject. 8. Two particles withsame (x t,) and (x2, t2). Same 3. In its present form, theprogram relies too t()? heavily on yes-no responses,s me of which are (no) br 9 not followed up carefully. An xpansion of such (yes) br 8a points might be worth theprtamming effort.

47 fir jr.17FfIff-777-111

V1112411101111111316111150gagtalli..-

4. An inflexibility of viewpoint in this program KINEMATICS (e.g., its insistence on graphical methods) may be (Alfred BorkWalter MichelsKarl Zinn) unfair to some students. The central problem This unit was first prepared as a printed program by can be alternatively solved by an application of Alfred Bork (Reed College) and Walter Michels (Bryn the mean value theorem to the difference of two Mawr College). It has been adapted for computer pre- functions. This alternative should perhaps be sentation on the COURSEWRITER system by Karl incorporated. Zinn (Center for Research on Learning and Teaching, 5. We deal here only with one-dimensional mo- The University of Michigan), but has not yet been com- tion. Thus. the full vector nature ofv is not pletely debugged or tested on students. explored. A supplementary section should be The program is based on a strobe photograph of an programmed with this objective in mind. object in non-uniform, two-dimensional motion, to- 6. More generally, it is not yet clear thatan ap- gether with a 'table of time and position measurements proach of this kind can be truly diagnostic. If made from the photograph. The student is asked five a student solves its problems easily, he probably basic questions about these data: has a good grasp of the concepts. But he may run 1. In which interval of the strobe photograph is the into trouble for many reasons other than faulty velocity probably constant? fundamental knowledge. Only experience with 2. Are you certain it is constant in this interval? the material, followed by extensive revision, can 3. In which interval(s) is the acceleration probably begin to throw light on the broad question. constant? 4. Write an algebraic expression to correctly repre- WEIGHTLESSNESS sent the east component of position at the time t (Arnold Arons) within the interval A to B of the motion. An instructional sequence rather thana diagnostic 5. What is the magnitude of the average velocity one, this program explores the subject of weightless- between the seventh and eighth seconds of the ness through the example of a mass accelerated in an motion? elevator. The program is constructed on a step-by- A student who answers each of these questions correctly step, question-and-answer sequence which leads the sails through the program in a few minutes. If the stu- student to understand the concept. The student is first dent has difficulty, however, he is shunted into various checked on his qualitative understanding of the first remedial branches to try to overcome his difficulties. and second laws of motion, and is then led to apply These remedial units include text displays, hints, and the second law to a body in an elevator and to extract further questions to diagnose the difficulty and lead the a verbal interpretation of the algebraic results. He is student to understand the problem. Some of the reme- next led through a description of his sensations of in- dial-diagnostic questions are centered around addi- creasing and decreasing weight as he himself becomes tional, simpler, one-dimensional strobe photographs. the accelerated object, and is finally led to articulate As a printed program, this unit was rather incon- what we mean by the term "sensation of weightless- venient to use. Each student needed the entire bulky ness" in the condition of free fall: program, whether he used only five pages or fifty pages. The sequence has remedial branches, hints, and at Shuffling through this many pages to find the right one one or two points suggests that the student sign off and was not a satisfying occupation for many students. A return to the program only after studying some textual tendency for students to become stuck in loops was also material on the laws of motion. The complete flow noted. By computerizing the program, these difficulties diagram, showing all of the statements in the program have been removed. However, it will require trial use and their sequencing, folds out from the back cover of with students to identify other problems which may this report. arise.

48 Pr7-111, .

appendix d

Four University-Based Systems'

I will describe here several computer systems thatare be a sufficient quantity and variety of these framesso not for sale anywhere, but that are used largely in that the student can be brandied effectively by the universities. I chose thesesystems because I have seen computer program to what he needs, as a function of them at least in partial operation and becauseat the deficiencies exhibited by his responseson previous present time they are being used in actual universityor frames. The student sees these frames projectedon a college courses... screen about ten inches square situated above his key- set. Another screen about half as large is used to display The SOCRATES System feedback messages to the student suchas correct an- swer, incorrect answer, etc. The system is now set up to The first system is probably the lowest in cost... It's called the SOCRATES system at the University of give instruction to fourteen students concurrently. It Illinois in the Training Research Laboratory. This is has a clock so that one can measure the amount of time it takes a student to make his response.... Dr. L. H. Stolurow's concept.. .It consists basically of a You can modest computer in the 1600 series of IBM andan IBM do some collection of data on the student's perform- 1710 control unit (i.e., a traffic manager) which allows ance and put this out on the disk or on IBM cards for later analysis.... students to communicate with the computer. Thecom- puter has a very small amount of highspeed memory; They are now giving a course in symbolic logic with the auxiliary memory consists ofa disk. The only this computer... to500 students....The time Stolu- means of getting information out of the computer is row expects the average student will be taught via the by cards or by outputting on the disk. The student computer is fifteen hours.. .this supposedly represents the equivalent of a full semester of coursework.... station has a set of fifteen keys which the studentuses to communicate his responses to the computer...It's largely meant to be used to selecta response which The PLATO Systenz2 would be of a multiple choice kind.... The next system I'd like to talk about is the PLATO Probably die most distinguished feature of thissys- system, under the direction of Donald L. Bitzer, also at tem is that you can load it with a large number (on the the University of Illinois. This one impressed me. It order of one to two thousand) of frames of visual dis- uses a CDC 1604 computer, but, it's not timeshared in play materialframes that have to be prepared in ad- the sense that the PLATO system can share the ma- vance on filmstrips....The intention is that there. chine with others who may, for instance, be compiling or computing at the same time. PLATO usurps the I This is an abstracted version of an invited speech to the Conference delivered by Joseph Rosenbaum of System Development Corporation's Educational and whole machine when it runs.. .There are twenty Training Staff. A full transcript of this speech is availabie from the Commission office. 2 A more detailed description of PLATO is given in Appendix A.

49 ^11101r''

student stations operating in one room. .It is thirty seconds and watch the array of sampling beha- actually being used for instruction in three courses:an vior.... electrical engineering course,a courseinlibrary science, and a course in clinical nursing. The UCLA System A distinguishing feature of the PLATO system is that, on the TV display tube, you can superimpose And now I'll describe a course that I'm involved graphic or keyboard material generated by the compu- with that's supposed to be operating one year from tzr over fixed slide projector material. The slides are now at UCLA. We will use a timeshared system, the actually 35 mm film frames mounted on transparent one in use at System Development Corporation, to do plastic sheets. One hundred twentytwo of these frames work from remote stations at UCLA. We will have at can be mounted in the system at one time, and the least two student stations: one in the psychology de- student can type over the slide display with the key- partment and one in the school of education; and pos- board, or the computer can generate graphic displays sibly a third in the school of public health... anaim of this course will be to see if wecan drive home over the slide image ....The other nice feature is that you can edit the course material online from one of concepts in statistics through the use of the computer the stations without having to go througha complete by essentially substituting sampling experiments for the difficult mathematics, usually probability, needed compilation of the course.... to demonstrate the concepts.... There is within PLATO a subsystem and a language The theory is that with this computer online interacting with the stu- called CATO....It makes use of FORTRANtype statements. You can express yourself, as a writer of a dent we can provide him with lots and lots of experi- course, in CATO and the system will compile and get ence or a simulated experience that may be Moser to his work experience. . your material ready for presentation.. . We hope to break the course down into essentially The Dartmouth Systems three pieces; one would be an expository piece which may have some programmed instruction in dialogue The third type of system in use today.. .is at Dart- form, but will certainly have some artfully chosen mouth. . ..They have attempted to introduce examples designed to dispel the mystery of whata computers into the undergraduate curriculum in the statistical test is for someone who doesn't have mathe- instruction of engineers, physicists, mathematicians, matical training, what a confidence interval is, what and statisticians...the language they use is called a measure of relationship between two variables may BASIC. It is a basic idea of the system to havea lan- be.... guage that's simple and that can be learned in a short We will have a laboratory phase where the student time by the student and the instructors....This will be presented with lots and lots of problems.... system has two sizeable GE computers...and about He will get a graded sequence of exercises where the thirty stations which are standard teletypes. (This isa data for these exercises will be randomly generated.. . . truly timeshared system...) The student in statistics Then there will be a vast array, perhaps sixty, statis- who goes on the machine has available a large library tical subroutines that the student can call up touse on of routines which he can call up for the more standard these problems.... statistical calculations....A student can also do a And the most daring piece...is that we have said lot of sampling experiments on a variety of distribu- that we will produce some question and answercapa- tions to get a feel for these distributions that he might bility in this system...with a limited fund of informa- not get from their analytic representations. He can tion to search, it may be feasible... tocollect a series vary the parameters of the distributions very easily and of queries as we observe them in the students andto ask the computer to spew out thousands of samples in build enough information into this base so that when the student queries the computer, it will reply appro- 3 The BASIC language used in the Dartmouth system is characterized briefly in Appendix G. An example of an instructional program in physics for the priately. It will permit him to ask questions tied to system is described in Appendix E. some of the problems in the expository phase.

50 .)

appendixe

Computational Mode Physics Programs

This appendix describes briefly some of the ways in the gravitational force. In the text the method of which the computer as a highspeed calculating ma- numerical integration is discussed, and the results com- chine has been introduced into undergraduate physics pared with the analytic answer. curricula at various colleges and universities. The ex- After a study of the examples in Feynman, the stu- amples that follow serve one or more of the following dents are asked to try to apply the techniques to other functions: to illustrate fundamental physical principlbs, forces. While most of them could formulate the prob- to give students some experience with simple tech- lems correctly, carrying out the calculations with At niques of numerical analysis, and to introduce students small enough for accurate results involves much hand to the computer and to the basic computational mode labor, and leads naturally to a demand for computa- programming languages. It should be stressed that tional assistance. these are programs which can be used at the present Before the students are introduced to the computer, time in almost any college which has a digital com- they write for the harmonic oscillator problem a set puter. Although the convenience of adaptation will of instructions intended for a "secretary"someone depend on the nature of the available equipment, most who knows nothing about mechanics but knows ;how of the programs described below can be converted to perform simple numerical operations and how to readily from the particular computer for which they follow directions. (A set of instructions of this kind, were developed to any other digital computer of simi- carefully done, will almost be a computer algorithm.) lar or greater capacity. These programs provide evi- Then, with no previous study of FORTRAN, the dence that, at least in the areas described below, the students are given FORTRAN programs for the har- computer can be, and indeed has been, used effectively monic oscillator and the gravitational problems, both in jhysics instruction. of which follow Feynman's method of calculation. These programs are discussed line by line, with expla- Numerical Integiation of Equations of Motion nations of what is happening at each step. Introducing students to FORTRAN inthis way rather than This example, devised by Alfred M. Bork for an through an instruction manual is similar to learning introductory course for nonscience students at Reed a language through conversation. College, is based on the approach to the equations of With the FORTRAN program for the harmonic motion given in Chapter 9 of the Feynman Lectures on oscillator running on an IBM 1620 computer, the Physics, Vol. I. In his illustration, Feynman follows the students can experiment with the parameters of the Euler method of replacing derivatives by average val- numrical integration. Feynman uses only one value of ues, but refines it by first calculating an initial half step At, so that it is not clear how the solution depends on in the velocity. He illustrates the method and the the size of the time interval. The students are allowed meaning of the equations of motion for two forces, to decide as a group what steps At should run, and to the linear force of the harmonic oscillator problem and enter this program into the computer. The exact solu-

51 tion is printed out along with the result of their Harmonic Oscillator in Quantum Mechanics numerical integration, showing what accuracy is ob- tained for various At's. The following example has been used by Alfred M. The students' first unassisted program involves solv- Bork with an IBM 1620 computer in sophomore classes ing the harmonic oscillator problem using the simple at. Reed College and the University of Alaska. Its pur- Euler method without putting the velocitieson the pose is to allow a discussion of the eigenvalue problem half step, which requires only a slight modification of in quantum mechanics before the student is ableto the existing program. The result surpriseseven expe- solve the Schriidinger equation by analytic methods. Two FORTRAN programs rienced physicists if they have had little previousex- were written for the har- perience in numerical analysis. Feynmansays that monic oscillator problem, the first using the Euler assigning the velocities to the middle of At isan method of integration and the second, described here, improvement, but now the students see directly just a more sophisticated method. The timeindependent how much it does improve the results. Schrodinger equation was integrated for various values With the gravitational force problem the students of the energy W specified by an initial data card. Each already have some idea of what step gives decent integration began at the origin, and for each value of answers, so the emphasis is on initial conditions. Feyn- W two different sets of initial conditionswere used; man works only one case, an elliptical orbit; he does first 4) = 1 and dtp/dx = 0, and second= 0, dtp/dx not suggest, and it is not suggested in class, that open = 1. No attempt uas made to normalize the solution. The calculation started with a Taylor series expansion orbits are possible. The problem is presentedas one of determining how variation of initial conditions affects at the origin, including terms in (ix)4. The integration the motion of the planet or satellite. The students de- method was that of Numerov,2 particularly suitablefor vise a plan for studying this systematically. linear secondorder equations withno first derivative The program allows them to enter new initial condi- term. tions from the typewriter whenever they wish. Most The calculation was stopped inone of two ways, groups decide that they will keep the position fixed depending on whether or not the solutionwas a pos- and vary the velocity. (It must be explainedto them sible eigenfunction. If the solution exceeded in abso- lute value a number specified that wild behavior occurs if the particle is allowedto on the data card (1.5 was get too close to the sun; that slight errors in the dis- satisfactory), the calculation proceeded to thenext val- tance will lead to large errors in the calculation for a ue of W. Otherwise each case continued until x was 1.5 1/r2 force at small distances.) Many students decideto greater than the classical turning point for that particu- keep the direction of the velocity fixed and alter only lar value of the energy, and amessage was typed indi- its magnitude. The first time students "fire" the satel- cating that the functionwas a possible eigenfunction. lite at a velocity sufficient to givea hyperbolic orbit, This did not prove that the square of :he functionwas they are surprised. As they watch thecomputer print integrable, but no such "proof" is forthcoming with out, someone gradually begins to realize the satellite" approximative methods. Indeed, it is almost certain might not come back! that any solution carried to larger and larger values of The next problem is locating the boundary between x will eventually diverge, for the method is approxi- mate, while an eigenvalue is a sharp, discrete occurr- closed orbits and open orbits. Since theprogram calcu- lates the total energy at an early stage, the relation ence. between open and closed orbits and the totalenergy Output was on punched cards, with spacing of the may emerge as an empirical generalization. independent variable in intervals of 0.1. Punching for The damped harmonic oscillator is the next assign- noneigenfunctions was controlled by a sense switch. A ment. The FORTRAN program is not too different program in the 1620 General Program Library (9. from the previous program for the oscillator.I The class 7.003, in GOTRAN) was modified for plotting the produces the program, runs it, and has the responsi- curves on Ditto masters. This program scaled the data. bility of finding the errors and correcting them. (A From a pedagogical point of view an online plotter, common error is to leave out a multiplication sign had it been available, would have offered distinct ad- between the damping constant and the velocity.) vantages.

2 D. R. Hartree, Numerical Analysis (Oxford University Press, New York, I By this time we have discussed how to write FORMAT statements. 1952), Sec. 7.22.

52 Lattice Vibration Spectrum The result once more leads him back to an analytic This is a problem or series of problems which has exploration of the behavior he sees. For example,a been used by Arthur Luehrman in the junioror strong peak shows up in his histogram and he notices senioryear course in solid state physics at Dartmouth that the value of the frequency there lies, in his earlier College.3 Typically at present, a onedimensionalar- plot, on a contour which runs through a saddlepoint rangement of springs and masses is worked out in of f(k). He is asked to explore this region analytically detail by hand, and the frequency f of each normal and to prove that in fact the peak is due toa loga- mode is found. Then the onedimensional reciprocal rithmic singularity in the lattice spectrum. space (kspace) is introduced, together with the Bril- In summary, this exerciseindepth brings a realistic louin Zone. This gives a geometrical significanceto the problem within grasp of the student and encourages normal modes, and f is thought of as a function ofa him, by the visible presence of unexpected details, to kspace argument. One would like to be able to pursue engage in a far closer analytic examination than would this same regime for a model more realistic than the occur without the numerical and graphical results. elastic line, where the effects of higher dimensionality are felt. Use of Computers in Lecture Demonstration The first step in this direction is a homework prob- The computer has been used in the following ways lem centered on a twodimensional square array of as an aide to classroom demonstration at MIT (Mal- masses and nearest neighbor springs. The analytic colm W. Strandberg). form of f(k) can be found easily, but its contentsare brought out by having the student plota family of 1. Band Theory for a One-Dimensional Solid some twenty curves of constant f on a graph whose axes In discussing the band theory of solids, a program are ks and ky. A computer is recommended for this, but with the PDP-1 computer allows an investigation of by no means necessary. A glance at the plots suggests the energy bands and wave functions in a onedimen- simple behavior of the function f(k) at certain points sional solid with such various lattice potentials as delta in kspace. The students are then asked to investigate function, parabolic (harmonic oscillator), sinewave, analytic expansions of f(k) near these points, andso to square well, and truncated Coulomb potentials. The, validate the hunches suggested by the numericalre- cathode ray tube output is used to present thewave sults. function visually. The limitation of CRT size isover- Next the lattice spectrum or density of states D(f) come by slowly drifting the section of the wave func- i.e., number of modes lying between f and fdfis tion viewed along the lattice for as many lattice dis- required. In the onedimensional problem this is noth- placements as desired. The computer seeks the edges of ing more than a trivial change of variable from kto f. bands using the periodicity and symmetry of thewave But in n dimensions it involves the integrationover functions at the band edges. The program has its n 1 dimensions in a very complicated manifold. greatest value in indicating to the student the sensi- Therefore itis never attempted in a conventional tivity, or insensitivity, of the essential features of band course, even though the student is told that it is one of theory to-changes in details of the model (i.e., strength the most important theoretical aspects ofa solid. of the delta function or the precise shape of the lattice However, the problem is quite simple to solve on a potential). computer with an eightline program (in the BASIC The fact that the wave functions are readily avail- language). The student is told to solve the problem by able is essential, since one can immediately investigate evaluating f(k) at 10,000 or so points in kspace, either the nature of the wave function in the allowed and for- randomly chosen or selected via a regular mesh. The bidden bands (its divergence in the forbidden bands range of f is divided into some fifty intervals and a his- being the physical reason for the forbiddenness). It also togram approximating D(f) is built up. The student provides a convenient method of explaining the typically solves this problem in about an hour of his existence of localized modes or surface states. More time and two or three minutes of (mediumsize)com- importantly, one can respond immediately to student puter time. questions; e.g., what will happen to the periodicityas the energy is increased above its value at the bottom of 3 The Dartmouth remote terminal computer system is described briefly in Ap- an allowed band? The wave functions are readily avail- pendix D, and the BASIC programming language which it uses is characterized in Appendix G. able, and the periodicity can be followed with energy

53 change to investigate the energy dependence of the feel for Hamilton's principle, and more generally for wave function. By such response, one can satisfy both any variational prir. It has not yet been imple- the analytically-oriented student and the student who mented, but woull:4uire a computer or remote ter- best understands qualitative physical discussions. minal with typewl ..er, cathode ray tube display, and The validity of the vicarious experience in band cal- light pen, and would proceed as follows: culation& afforded by the computer is reflected in the 1. The student types his name and theprogram level of student discussion in following periods. For name. example, students become interested in the dependence 2. The cathode ray tube or typewriter asks him (via of the actual band structure on the potential; could, in printed message) to specify the Lagrangianor fact, the potential be inferred from the band structure? the potential function. Having gone this far with a one-dimensional solid, it 3. The student replies and is asked to type in the seems to be easier for the student to accept some of the function. simple ideas connected with more realistic three- 4. Axes with full labels appearon the screen. They dimensional models. remain during the rest of theprogram. 2. Pendulum 5. The student is asked to mark the end-points of the motion with his light pen, and two points A second example of the use ofa computer in lec- tures is intended for a freshman physics course, and (labeled "initial" and "final")appear and stay on the screen. concerns the motion of a pendulum. Here the velocity, 6. The student draws any curve between the points, acceleration, and displacement of the pendulumare and the value of the action (with label) for the calculated and displayed on the computer CRTas a given Lagrangian and path appears function of time. The initial displacementcan be var- on the cath- ied and the breakdown of the usual linear approxima- ode ray tube face. tion can be studied by noting the effect of the initial 7. The student draws another possible path which displacement on the time dependence and acceleration, appears with the first path. The action for this path also appears on the scope. The path with and on the period. The computer alsoconstructs a table of periods for various initial displacements. These the least action of the two stayson the screen, displacements are plotted to show the student where with the value of its action, and the other path linear approximation breaks down, the direction of fades. The action is labeled "best path drawn." change of the period, and its rate of increase with ini- 8. The student continues in this fashion, tryingto tial displacement. This quantitative investigation of make the action smaller and smaller. 9. When he decides that he has tried long enough, the real motion of the pendulum helps the studentto gain an intuitive feeling for the limits of validity of the he asks for the physical path and its associated linear approximation, the conditions under which the action. This is drawn ina way that is distinguish- approximation breaks down, and the rate at which able from the "best" path of the student. If de- error develops; useful and profitable points to make sired, the student can terminate theprogram here. economically with the computer, but too time-consum- ing for hand calculation. 10. The student can ask for his best path to be erased. Variational Principles and Classical Mechanics 11. He can then draw paths in the neighborhood of the physical path and see directly thatany devi- This is an example of a program designed to give the ation increases the action. student (sophomore- or junior-level science major)a 12. Termination.

54 ,-77-,4--Ttrt-i.-Th."7-11."',

r appendix f

University of California, Santa Barbara, Computer System

Over the past several years a problemorientedpro- numbers, and whose repertory of instructions in- gramming system and computer terminal have been cludes the basic operations of classical analysis developed, largely at TRW Systems in Canoga Park. (suchas exponentiation,trigfunctions,etc.) Although the system was devised with the solution of rather than only those of arithmetic. The simplest research--type problems in mind, it has recently been kind of function on which the machine would used successfully for instructionalpurposes at the Uni- operate, for instance, would be a real function X. versity of California, Santa Barbaracampus. Currently To the machine, this function would be a series we have a classroom at Santa Barbara equipped with of values of the function sixteen of these computer terminals. In addition, there is one terminal at UCLA tied into the SantaBarbara X = (x1, x2, x3,- - - - xN), computer by telephone line, and there willson be or a real vector. At present, N is limited to values two more stations at Harvard tied into it. of 124 or less at Santa Barbara. Complex func- The system was designed around four central charac- tions are represented as two vector arrays, andso teristics: forth. In the above case, the Xkey on thecon- 1. Direct control. The user has immediate command sole represents not just a single number, but the of the computer, and can, froma keyboard, initi- whole array of numbers which describe the func- ate a number of basic subroutines built into the tion. system, as well as additional ones which he creates 4. Console Programming. By simple keyboard oper- by console programming. ations, the user can, at the console, combine any 2. Direct Feedback. The results ofany calculation of the basic subroutines into new ones specialized are immediately available to the user, displayed to his needs. These new subroutines can then be on a cathode ray tube (CRT) either as numbers assigned to available keys stored in the disk or in graphical form. memory of the computer, and later called upon 3. Functional Orientation. The computer ispro- by merely pressing the assigned key, in the same grammed to act as a "function computer"; that is, way that the basic, builtin subroutines are called. one which deals with functions (in the mathe- Such special subroutines can, in turn, be included matical sense) as entities, rather than individual in more complicated subroutines, thus providing all of the programming aspects required incom- 1 The following is a written version of an invited talk presented to the Confer- ence by Glen J. Culler, Director of the University of California, Santa Bar- puting, but without the time lags typically associ- bara Computer Center, and a Professor of Mathematics at UCSB. ated with conventional procedures.

55 J keysThe doubleare color keyboard coded according of the BBN to theirTeleputer functional console. role Thein the system. upper keyboard is for operators, the lower for operands. In addition to the labels shown, the Figure 1 l'itlemon.Nros'WV."11SPOrITP.,17' The central computer used for the system at Santa a small subset of operator keys designated as "level Barbara happens to be a time-sharing Ramo-Woold- indicators," analogous to the case shift on a type- ridge RW400, although nothing in the programming writer. At present, in the nine basic levels of the sys- system is specific to this kind of computer. One of the tem, the operators operate on: consoles used at Santa Barbara is shown in Fig. 1.2 At I. single numbers (or single components of a vec- present, typewriter keyboards and storage oscilloscopes tor); provide the most economical basic input/output de- II. real functions or real vectors; vices for on-line computing. The storage oscilloscope III. complex functions or complex vectors; is a standard Tektronix model, and the system is pro- IV. (not implemented at present); grammed to write alphanumeric characters on its face V. (not implemented at present); and to construct graphical displays. Alphanumeric VI. real matrices (under development); characters are written at a rate of about 25/sec and VII. complex matrices (under development); displayed about twenty-five to a line across the five- VIII. statistical programs and functions (under de- inch CRT face. As an input device, the double key- velopment); and board shown in Fig. 2 is mounted on the console. The IX. editing programs with alphanumeric capabili- keys operate microswitches, and are designed to doso ties (under development). quietly. This is a necessary feature of consoles to be used in a classroom. As you can see, theupper key- The operation EXPON X would, for example, pro- board is associated with operators, and the lowerone duce on level I one value exp (X); on level II the ex- with operands. Each operation is carried out by push- ponential of each of the N components of the vector ing a single key of the upper keyboard. X;, and on level III the real and imaginary parts of the Being function-oriented, there arc several levelson exponential of each of the N components of X. In which the system can operate. Levels are changed by other words, on levels I, II, and III, there arerespec- tively 1, N, and 2N results of each operation, be ita basic keyboard operation or one which has beenpro- grammed and stored. Because the system is function- oriented, operations on level I are very inefficient;you spend as much time locating the operand as you do performing the operation. Returning to the lower or operand keyboard, each key corresponds to a storage location insome mass storage device (a magnetic disk in the Santa Barbara computer). Data transfers between this and thecom- puter are effected with the operator keys LOAD and STORE. For instance, pressing the two keys LOAD A (operator and operand, respectively) brings the data Itkett7A Alt e in storage location A-a number, vector,or some other lit. 1 it 1"-- kind of list, depending on the level-into thecom- puter's magnetic core memory, while STORE Aac- complishes the converse. To facilitate the function of console programming and to increase the addressable storage capacity of the system, nine user levels are available on each key. For Figure 2 example, to store a program, under RS onuser level The Bolt Beranek and Newman Teleputer console, used in V, one presses the four keys the Santa Barbara on-line computer system. STORE USER V RS 2 These consoles are now being manufactured commercially by Bolt Beranek Additional programs could be stored under the RS- and Newman. A more detailed description of the BBN Teleputer console ap- pears in Appendix B. key on the other user levels, if desired.

57 e-

A further, very detailed description of theprogram- The student consoles are connected with the teacher's ming system would be out of place here. For those console in such a way that: who would like more specific informationon how the 1. The teacher can display what he is doingon each system works, a detailed, annotated example ofa of the student terminals. rather simple program has been appendedto this re- port. This particular example is one which might be 2. The student terminals can operate independently, suitable for use in a calculuscourse (or even a physics but the teacher can dialany one of them and course studying velocity and acceleration): a program monitor the student's work. iswritten to perform a numerical differentiation, 3. An individual studentcan switch his terminal to stored on the disk, then calledout and used to calcu- the teacher mode, and display his workto the late the derivative ofa sine function for various values rest of the.class on their terminals. of the increment IL For the calculus course, the consoles are used during Now, how do we use these terminals in teaching the off-semester so that we don't have to work with undergraduates at Santa Barbara? The sixteen console 1,000 students. There are three lectures plusone sec- stations, located in the classroomas shown in Fig. 3, tion meeting per week for each student, with about are presently used in three courses: a second-semester thirty students per section. The sectionsare then split calculus course, a constructive methods (computing) in two so as to fit into the computer terminal lab, and course which I teach, and a biometrics course. they alternate every other week there. ina sense, the

Figure 3 The computer terminal classroomat the University of California, Santa Barbara. The instructor's console is visiblein the upper right hand corner of the room. Several of the consolesare shown with their display housings removed, illustrating that the display units are standard TektronixType 564 storage oscilloscopes, each with Type 2A60 verticaland horizontal plugin amplifiers.

58 terminals are used as a very powerful blackboard. I've II-type sophistication (i.e., lists of real numbers), using found that, sitting and talking to the class,. I often a computer with 5-microsecond multiply tinie, full think of something to illustrate; I program it quickly, core storage in order to get the flow IT, and a good show it, and go on to do something else just as I would disk, the system could handle 125 people at consoles, do on the blackboard, but of course with a power the leaving them all with the feeling they can do,any- blackboard does not have. For instance, when the thing you want them to. But since half of them won't classis studying the concept of the derivative, the be doing anything, you should still have about 50 teacher may illustrate the definition by constructing, per cent of the computing time available for back- on the spot, the simple program appended to this re- ground calculations on the time-sharing system. port. He can use it on one example, and the indi- The on-line system of computer terminals we've de- vidual students can try it on functions of theirown veloped was designed to act as an extension or aug- choosing. Later on, when studying differentiation of mentation of the reasoning power of the human complicated, perhaps transcendental functions, they opeiator, usable by him in the most naturalway and can use the same program to either gain some intuition under his continuous control. As such it has been of into what the derivative should look like, or to check enormous use' in research calculations, and its appli- their analytical result numerically. Or, instead of cation to instruction is going to increase greatly the using the stored program created by the teacher, they scope of things that we can do for students in quanti- could be asked to construct their own little numerical tative math and science courses. differentiation program. By such use of the terminals, one might achieve an organized laboratory treatment References of calculus which may be orders of magnitude, better than what we've been doing in our calculus sections. G. J. Culler and B. D. Fried, "The TRW Two- For his Biometrics course at Santa Barbara, Jim Station On-Line Scientific Computer: General Ross has incorporated a random number generator, Description." In Computer Augmentation" of Hu- and a SORT operation under the SQRT key (take man Reasoning, edited by Margo A. Sass and the tail off of the Q and it becomes SORT). The William D. Wilkinson (Washington, D. C.: Spar- SORT operation orders a list of numbers by magni- tan Books, 1966). tude. With these and other operations which he's W. J: Karpius, ed., On-ine Computing in Time- programmed, he can use the computer to illustrate Shared Man-Computer Systems (New York: Mc- quickly and numerically many of the statistical ideas Graw-Hill, fall 1965). that his students really don't understand from a mathe- This book, based on lectures given under the aus- matical point of view. pices of the University of California extension In order to give *the user the feeling that, when he service, contains a chapter by 'G. J. Culler which punches the SINE key, the sine of a function is really is in essence a user's manual for the BBN Tele- computed, the turn-around or response time of the puter, and a chapter by B. D. Fried on problem- system should be of the order of 1/10 sec. At level solving techniques with such an on-line terminal.

59 NOS,FAMED PAGEBLANK. PRECEDING

A SIMPLE PROGR4M FOR THE SANTA BARBARA

ON-LINE COMPUTER SYSTEM

Keyboard Entries Computer Displays (Each underlined symbolor group. of symbols represents, one key.)

1111111~. 1. IX CTX A RETURN 3 o

EXPLANATION

A list of real function values, or a vector, occursas a column in a two-dimensional array.In answer to the question "ARRAY TYPE" the nature of an array is specified as Real by depressing the key R. The size of real, arrays is set at 50 columns (M) and 120rows (N) in answer to appropriate questions displayed by the computer.This then defines any real function (column vector) as consisting of 120 numerical values.

To initiate the process of defining A, the user requests level IX (editing programs) and asks for the context comment stored under A (9TX A). Depressing the RETURN key (carriage return) inre- sponse to the request "PUSH CARR" brings forth the above ques- tion-and-answer sequence defining the nature and size ofarrays. ERASE* LISTII LOAD X USER I + II STORE G LOAD X + H USER + II - G WI-- STORE D DISPLAY D LIST STORE USER I DIFF

EXPLANATION

The CRT screen is cleared (ERASE), anda numerical differentiation program is written (the keys between LIST... LIST) on level II (real functions) to compute the derivative of a function f ofan indepen- dent variable X. Reading the program itself from left to Tight,a set of values of X is loaded into comiutermemory, and the function E (X) iscomputed and stored in location G on the disk or drum. I. is any arbitrary function which has been programmed (seestep 4) and stored under the operation key + onuser level I.In addition to this function, the display for the Z which appearson the CRT has been previously prorammed and stored on user level I under the+ key. Following the VI to user level I,the computer is shifted back to level II(real functions ) by depressing the II keyon the operation keyboard.(It may or ma not have been left in level II by thepro- gramF.)Similarly (X+H) is computed, G subtracted from it, the difference divided by H, and the quotient stored under D.Then G=116(X) and D(X)are displayed on the CRT. STORE USER I DIFF stores this program under the key DIFF on user level I.

* Some of the terminals used in the Santa Barbara system donot have ERASE keys. On such terminals, the ID key performs theerase func tion when the user is typing or listing informations and the SPACE bar performs that function when calculations are being carriedout.

62 LISTPROGRAM DIFF FOR THE N UMERICAL CA1CU1,217fi.-0N "5 I'THE DERIVATIVE 3 SHIFT. 2 F SHIFT1 jXjj = S HIFT 2.I SHIFT 1LX+ H HIFT 2 SUBPROGRAMFSHIFT TO,T. 1RII/ COMPUTE F MUST HAVE BEEN STORED O N USER I UNDER

A S HIFT 2 -SHIFT 1.. ALUES orxWND HMUST. H AVE AL-§li BEEN STORED. LIST STORE

E XPLANATION

The material between LIST... LIST is typed in as the text of a comment and stored under the key DIFF on user level I as a context (CTX) comment which explains what the program does. The comment can be displayed on the CRT before the program runs, as in step 6 below. Note that to display the fancy symbol-:F one must shift "casein typing;i. e. ,shift from symbol table level 1 to 2, then back again. This bas been done in lines 4 and 7 of the above display, but not for the F in line 6.The sym- boitahas previously been formed and stored bya procedure which we do not discuss here.Its display is stored under both the operation key + on user level I and the operand key F on symbol table level 2.

4. ERASE The symbols between

LIST II S.1 LIST STORE USER I + LIST . . . LIST appear on the CRT.

E XPLANATION

A subprogram to calculater(X)=X2for real functions is stored under the key + on user level I.

63 F

5. II ID 5 + 5 STORE X LOAD Since the computer As not 0 1 STORE 11' placed in the LIST mode, this series of .keys results in no further CRT display.

EXPLANATION

This series of operations loads 120 numbers,equally spaced in the interval -1 to +1, into computermemory (this is the built-

in ID function). These are converted into120 numbers equally. spaced between zero and 10,and stored under operand key X (the independent variable).His set equal to 0.1.

6. ERASE USER I CTX DIFF (Thiscauses the commentto be displayed.) USER I DIFF (This causes the program itself toNun, resulting in the .twocurves shown superimposed on the comment.)

EXPLANATION

The CRT is erased, the contextcomment displayed and the program run, giving a graphic display oil (x)xrz andDIFF Y(X)= 2X for05 X.:510.

O,

64 7 ERASE The CRT is erased and the LIST II LOAD Y SIN STORE Z LOAD Y information entered in the COS +Z LIST STORE USER I + LIST mode is displayed.

EXPLANATION

A new function for L (X) r. sin `X + cos X is programmed and stored under the operation key 4 on user level I.

8. LIST II LOAD X USER I + STORE G LOAD X The information entered in 77 H USER I + G % H STORE D LOAD H 'N72 the LIST mode (between STORE H DISPLAY D G USER 1 LIST LIST . . . LIT!) is dis- STORE USER I DIFF played on the CRT along with that remaining from step 7. (When the + key is depressed, the symbol E is displayed.)

EXPLANATION

The main program DIFF of step 2 has been rewritten to iterate for decreasing values of H.It has been caused to terminate on user level I so that it can be repeated automatically by merely depressingthe DIFF key, in the manner demonstrated by step 10.

65 -Firig.717=1"."77.177""17". ,!1

9: ERASE The previous display is II ID 6. 2 8 STORE x: SUB X LOAD erased,' and X and Y STORE 2 Y DISPLAY Y III REFLECT coordinate axesappear STORE YDISPLAY Y II centered on the CRT.

EXPLANATION

First the 120 values of the independent variableare set to range between- 211-6X .S. 21r . The keys SUB X put the listXinto the X-coordinates (abscissa) of the graphic display. The next six keys cause the function Y= 0 (the X-axis) to be displayed. Transfering to level III (Complex functions), the REFLECT operation interchanges the X and Y (real and imaginary) axes, so that STORE X DISPLAY Y plots the Y- axis of the coordinate system. 4 Finally, the computeris transferred back to level II operands. 7.v

10. LOAD 1 STORE H USER I REPT DIFF El. RETURN

H =1/8 H =1/4 H =1/2 H =1

EXPLANATION

The initial value of H is set equal to 1 and theprogram is repeated ( ED four times, for values of H = 1, 0.5, 0.25, and 0.125. The RETURN key is depressed to inform the computer that theuser has finished typing in the number of repetitions desired. Otherwise the computer would not know whether further digits were to follow the 4: for example, 42 or 497 repetitions. The photograph showsthe resulting CRT display, with the following variations: a) The coordinate axes resulting from step 9are not shown. b) The'text at the top should not appear (thiswas added to the photo- graph for identification.) c) All four curves should be continuous rather than dotted,as three of them are. The dotting was programmed speciallyto distin- guish the curves.

(It is interesting to note that the principalerror caused by choosing a large increment H is in the phase and amplitude of the resulting derivative, not in its smoothness.This result was at first mildly surprising to the person who actually ran, theprogram,and illustrates the type of learning whichcan occur at such a computer console.)

67

isazeNc- 11.

t*

EXPLANATION

To illustrate the effect of rounding off errors for very small H, the derivative of sin X + cos X was calculated with H = 2 5 x 10-7 (continuous, jaggedcurve). It is compared with the true derivative cos X- sin X (dotted curve). The coordinate axes are also shown here.

68 Gricika' Aig4miwkfilt4.zikuoias ttrivoskaWftiAragegair.a0m4-44.11115...

appendixg

Computational Mode ComputerLanguages

This appendix provides brief, informalcommentary JOSS on some of the more commonly used computer lan- guages for programming numerical computations.1 JOSS is an algebraic language whichwas developed by the RAND Corporation foruse at timesharing, FORTRAN typewriterlike terminals. Itcan be used either to program or to make the terminals operate as electronic FORTRAN is by far the most commonly usedcom- desk calculators. Because it is intended for terminal puter language for computational mode programs at use, it is designed to provide rapid feedback ofgram- present. It was designed by IBM in 1957 for the IBM matical errors made by theprogrammer. Variations 704; but is now availableon almost every computer of JOSS, under slightly different in the world. It is names, are now avail- an algebraic language which de- able at the University of California at Irvine (JOSSI) scribes calculations using expressions similarto those and at the University of California at Berkeley (CAL, used in algebra. As with all computer languages, FOR- not to be confused with ComputerAssisted Learning). TRAN has many different "dialects," the three most A version called TELCOMP is available for widelyused being FORTRAN, FORTRAN use in II, and the Boston area through Bolt Beranek and Newman. FORTRAN IV. Although there isno consistency in the use of these terms, FORTRANIf usually includes subroutines in the language, and FORTRANIV usu- BASIC ally includes theuse of logical "IF" statements and complex variables. BASIC is an algebraic terminal language, similar in some ways to JOSS, which was designed at Dartmouth ALGOL College for use on their timesharedcomputer system. It is also used at General Electric as a timesharing ALGOL is a second generation algebraic language, language, and is available to other colleges through succeeding FORTRAN andso having a somewhat the use of centralized GE machines. more logical structure. ALGOL is not nearlyas widely used in this countryas it is in Europe. There are, however, many American machines with ALGOLcom- QUIKTRAN pilers, although these compilers often omitsome of the more esoteric features of the language. QUIKTRAN isa terminaloriented version of FORTRAN developed by IBM and available from I Descriptions of existing programming languages for CALin the linguistic them at terminals in certain large cities. Unlike JOSS mode are contained in Appendix A. and BASIC, it uses the full complexity of FORTRAN.

69 PL /1 PL/1 is a new language announced by IBM for implementation on some versions of their System 360 computer series. As of this writing, no experience is available with PL/1 compilers. The language com- bines the features of both an alegbraic language and a symbol or listprocessing language? As an alge- braic language it could be called a "third generation" language, succeeding FORTRAN and ALGOL. Be- cause it combines algebraic and listprocessing facili- ties,itallows complex programs which use both linguistic and computational modes;

2 A listprocessing language is specifically designed for the efficient processing of verbal information. For example, the COURSEWRITER and MENTOR systems described in Appendix A are essentially listprocessing languages, u opposed to the computationoriented languages described here.

70 idbaue.fielistie",41,

appendix h

Glossary

This glossary contains definitions or explanations of Bandwidth:The range of frequencies which can be many of the more frequently used and less familiar transmitted over a communications channel (tele- terms employed by computer specialists. Although an phone line, radio channel, etc.). The bandwidth effort has been made to explain unfamiliar terms when determines the amount and quality of information they appear in the body and in the other appendices of which can be transmitted through the channel per this Report, or to avoid using them altogether, we have second (bps). This is equivalent to cycles per sec- not been entirely successful in doing so. Therefore the ond (cps) or Hertz (Hz), with the usual multiples, glossary will be of some use in reading the rest of the Kilo- and Mega-. Report. In addition, the publications of computer com- Batch processing: A method of processing in which ponent manufacturers and computer experts are some- a number of similar input items or programs are times distinguished by a proliferation of somewhat accumulated and processed together. obscure technical terminology. It is hoped that this glossary will also aid the reader in referring to and Binary computer: A device using on-off switches understanding other technical literature on computer (electromechanical relays, bi-stable circuits [vac- systems in general, and CAL systems in particular. uum tube or transistor}, magnetic rings, etc.) to represent numbers in the binary system for cal- Access time:Time required to obtain information culations. 1 from storage (read-time), or to put information Bit:Contraction of term "binary digit." away in storage (write-time). Broadband:Of large bandwidth: at least bandwidth Algorithm: "A rule of procedure for solving a recur- greater than that of ordinary unconditioned dial- rent mathematical problem." (Quoted from Web- able telephone circuits, which is about 2,000 Hz ster's Third New International Dictionary.) or bits/sec. Analog computer: A device which uses voltages, Broadband Exchange Service (BXS): A data com- forces, fluid volume, or other continuously vari- munications exchange switching service offered by able physical quantities to represent numbers in the Western Union Telegraph Company. The calculations. service provides full duplex facilities at band- ASCII:American Standard Code for Information widths up to 4 KHz data rates up to about 2,100 Interchange. This is the character code established bits/sec), with bandwidths up to 48 KHz a possi- as standard by the American Standards Associa- bility in the near future. The user can dial the tion, and consisting of eight information bits plus particular bandwidth he wants as well as the party one start and two stop bits per character, a total he wishes to call, and can transmit and receive of 11 bits/character. voice communications as well as data.

71 LINIAAiicisa:4stamix;"44"441.1.11.4.41

Buffer: A storage device used to compensate fora Data set:A device which converts the digital pulses difference in rate of flow of dataor time of occur- from a computer or an 170 terminal into audio rence of events when transmitting data fromone frequency tone pulses for transmissionover tele- device to another. The storage unit is oftena mag- phone lines or other communication channels. It netic core memory, and is referredto as buffer is a telephone-like device, with provision for dial- memory or buffer storage. ing another party and for voice communication Byte: A group of bits (usually six to eight) forming with the other end of the line. a character. Disk: A stack of disks coated with magnetic material CAI:Computer-assisted instruction; computer-aid- for the storage of information. Bitscan be stored ed instruction; computer-augmented instruction. upon and read from it while it is revolving at high CAL:Computer-assisted learning. speeds. CBI:Computer-based instruction. Down-Time: Time when a machine isnot operat- ing correctly because of machine failure. Channel: A path for electrical signal transmission between two or more points. Also calleda circuit, Drum: A cylinder coaled with magnetic material facility, line, link, or path. for the storage of information. Bitscan be stored upon and recovered from it while it is revolving Character:A digit, letter, or other symbol, usually at high speeds. requiring six to eight bits of storage. In datatrans- mission, start and stop bitsmay be required for Duplex or full duplex:in communications, pertain- each character in addition to information bits.In ing to simultaneous two-way, independent trans- the ASCII code, for instance,a total of 11 bits/ mission in both directions. In contrastto half character is required for transmission. duplex (see below). Compiler:A computer program for the translation Facsimile (FAX):Transmission of photographs, of instructions expressed ina user language (for maps, diagrams, etc., over communication chan- example, algebraic formulas) into machine lan- nels. The image is scanned at the transmitter,re- guage. constructed at the receiving station, and dupli- cated on some form of paper. Core: The rapid access memory ofa central process- ing unit; usually madeup of many small rings Foreign exchange service:A telephone exchange (cores) of magnetic material, whichmay be in ei- service in which the subscriber's telephone (or data ther of two states of magnetic polarization. station) is effectively located in a distant exchange area. An unlimited number of calls or data con- CPU: central processing unit. The central sectionof nectitms can then be made within the distant a computer, incimling control, arithmetic, and exchange area for a flat monthly charge. This memory units. service is limited to the usual telephone line data CRT: Cathode ray tube. Incommon use as a display rates of less than 2,000 bits/sec. device. Half-duplex:Pertaining to an alternate, one-way- Cursor: A point or line' of light displayedon the at-a-time transmission facility (sometimes referred CRT, the position of which is under the amtrol of to as a "single"). In contrast to duplex or full du- either the user or the computer. Thecursor is used plex (see above). to indicate the point at which the next displayor Hardware: Computer components and equipment. editing operation is to occur. Interface: A shared boundary; for example, the Data Phone: A trade mark of the American Tele- boundary between two subsystemsor two devices. phone and Telegraph Companyto identify the An interlace unit ina remote terminal computer data sets manufactured and supplied by the Bell system is a hardware component which "matches" System for use in transmission of dataover the devices to each other; for instance,a computer to regular telephone network. It is alsoa service mark several telephone lines from remote terminals, of the Bell System which identifies the transmis- or a remote station to a telephone line. The unit sion of data over the regular telephonenetwork may contain buffer memory, switching logic, and/ (Data Phone service). or multiplexing facilities.

72 0.,....adam4kk..4.4)AotbkistioigAveraiiiirciisg4isa.c4Anoliblimakemasv

Interrupt:A hardware feature which allows the RAND tablet:A metal writing surface developed by computer to stop working momentarily on one the RAND Corporation for input of graphic in- task, handle the interrupting task, and return to formation to a computer through the use of a the first without losing information or interim special writing stylus. results of processing. Real-time:Performance of data processing during INWATS: Similar to WATS (Wide Area Telephone the actual time the physical process producing the Service-see below), but allows inward calls at a data transpires, in order, that results of the compu- flat monthly rate. tation can be used to guide the physical process. 1/ 0:Input/output of information to and from com- Refreshed CRT display:The more conventional puters. Usually refers to devices such as electric type of CRT display, in which the image to be dis- typewriter, card reader and punch, paper tape played is re-formed or "refreshed" at a rate of reader and punch, etc. thirty to sixty times per second, so that it will per- K:Thousand; e.g., 32K words of memory means sist without objectionable flicker. This requires 32,000 words of computer memory. scanning logic and buffer storage to drive the LDX: Long Distance Xerography. A name used by CRT, However, changes in the display can be the Xerox Corporation to identify its high-speed made rapiilly by merely changing the appropriate facsimile system. The system uses Xerox terminal information in buffer storage, without destroying equipment and awide-band communication and re-forming the entire display. (See description channel. of the storage oscilloscope below.) Light pen: A photo-sensitive device used for com- Response time:The amount of time elapsed be- munication with a computer. When held against tween generation of an inquiry at a data commu- the face of a cathode ray tube, its position can be nications terminal and receipt of a response at sensed. For instance, if the computer is suitably that same terminal. programmed, the position of the light pen can be Software:Computer programs, as contrasted to com- interpreted in terms of a coordinate grid. The puter components (hardware). device can be used in this way to enter arbitrary Station:One of the input or output points on a graphical information, sketched by the operator communications system. on the CRT, into the computer memory in digital form. Storage oscilloscope: A device in which displays are stored on the face of the CRT by electrostatic Line switching: The technique of temporarily con- means, In order to change any piece of the stored necting two lines together, so that remote stations information, the entire display must be erased and may interchange information directly, re-formed, making this device slower in response Link:The same as a channel (see above). than refreshed CRT displays. At present, storage Multiplexing:The division of a transmission facil- oscilloscopes seem to be less expensive than re- ity into two or more channels, over each of which freshed displays, but the situation may reverse in independent signals or data may be transmitted. the near future.(See description of refreshed dis- play above.) On-line:Connected directly to the central com- puter. Storage protect: A hardware feature which prohib- its one user in a shared system from destroying the Polling: A centrally-controlled method of calling or information stored in memory allocated to other interrogating a number of remote stations sequen- users. tially, to permit them to transmit information. Process controller: A compmer or computer sub- Student station:I/Oequipment designed for stn. system designed to communicate with and control dent use, to permitthe student to interact with industrial, laboratory, or other processes. Such the computer. equipment may be useful in CAL because of the Teleprinter:A termreferring to the equipment convenience of attaching teaching stations and in- used in a printingtelegraph system. A teletype- structional laboratory apparatus to them. writer.

73 Tele-processing: A form of information handling though the computer actually services eachuser in in which a data processing system utilizescommu- sequence, its speed makes it appear that the users nication lines bet.,een stations and the processing are all handled simultaneously. unit (computer). Vector generation: The capability of drawinga line Teletypewriter exchange service:An automatic between two specified pointson a terminal display exchange switching service providedon a nation- device. wide basis by the American Telephone and Tele- Voice grade channel: A communication channel graph Company (TWX) and the Western Union suitable for transmission of speech, digitalor ana- Telegraph Company (Telex). log data, or facsimile, generally witha frequency TELPAK: A wide-band, leased line information pass band of about 300 to 3,000 Hz. Voice grade transmission service offered by communications channels can carry data at rates greater than about common carriers. 2,000 bits/sec only if they are specially condi- tioned. Terminal: A device attached directly toa computer through telephone lines, cables,or other commu- Wide Area Telephone Service (WATS): A service nications links, and designed foruser-computer provided by telephone companies which, by the interaction. Terminals may be located adjacent use of an access line, permits a customer to make to the computer or at a remote location. an unlimited number of calls to telephones or data sets in a specific geographicalzone for a flat Tie line:A private communication channel of the monthly charge. type provided by communications commoncar- riers (e.g., AT&T or Western Union) NI linking Word: A set of bits sufficient toexpress one com- two or more points. puter instruction. Conventionally, a word consists of six characters, and therefore thirty-sixto forty- Time sharing: A method of operation in whicha eight information bits, or up to sixty-six bits for computer facility is shared by several users for dif- data transmission (see definitions of character and ferent purposes at (apparently) thesame time. Al- ASCII).

74 _.40twaggeghtmi. r

appendix i

List of Participants

E. N. Adams Harry N. Cantrell ComputerAssisted Instruction General Electric Division of Phoenix IBM Instructional Systems Development Compti ter Department Watson Research Center Deer Valley Park Plant Box 218 13430 North Black Canyon Highway Yorktown Heights, New York 10598 Phoenix, Arizona 85023

Bruce Arden Glenn Culler Computer Center Computer Center The University of Michigan University of California, Santa Barbara 1000 University Hall Santa Barbara, California 93107 Ann Arbor, Michigan 48104 Arnold B. Arons Kenneth Davis Department of Physics Department of Physics Amherst College Reed College Amherst, Massachusetts 01002 Portland, Oregon 97202 Alfred M. Bork David Feign Department of Physics University of California, Irvine Reed College Irvine, California 95616 Portland, Oregon 97202 Wallace Feurzeig Charles Branscomb Bolt Beranek and Newman IBM Instructional Systems Development 50 Moulton Street Arm°. 'nk, New York 10504 Cambridge, Massachusetts 02138 Lewis Bright Westinghouse Corporation Kenneth W. Ford 3 Gateway Center Physics Department Pittsburgh, Pennsylvania 15230 University of California, Irvine Irvine, California 95616 Donald Brown Center for Research on Learning and Teaching Burton Fried The University of Michigan Department of Physics 1315 Hill Street University of California, Los Angeles Ann Arbor, Michigan 48104 Los Angeles, California 90024

75 William J. Galloway William B. Lonergan Bolt Beranek and Newman Radio Corporation of America Van Nuys, California Electronic Data Processing Division Building 204-2 Ralph W. Gerard Cherry Hill, New Jersey 08101 University of California, Irvine Irvine, California 95616 Arthur Luehrman Department of Physics Richard B. Gooch Dartmouth College Control Data Corporation Hanover, New Hampshire 03755 8535 Florence Avenue Dowdney, California 90240 George Michael Lawrence Radiation Laboratory Everett M. Hafner Livermore, California 94550 Department of Physics University of Rochester Thomas J. Padden Rochester, New York 14627 Phi lco Corporation 3900 Welsh Road Frank Harris Willow Grove, Pennsylvania Department of Chemistry Thomas R. Palfrey Stanford University Department of Physics Palo Alto, California 94395 Purdue University Robert Hulsizer Lafayette, Indiana 47907 Department of Physics Joseph Rosenbaum Massachusetts Institute of Technology System Development Corporation Cambridge, Massachusetts 02139 2500 Colorado Avenue E. Leonard Jossem Santa Monica, California 90404 Department of Physics Noah Sherman The Ohio State University Department of Physics 174 W. 18th Avenue The University of Michigan Columbus, Ohio 43210 Ann Arbor, Michigan 48104 John F. Kalbach Donald L. Shirer Burroughs Corporation Department of Physics 460 Sierra Madre Zilla Valparaiso University Pasadena, California 91107 Valparaiso, Indiana 46383 James Kearns Malcolm W. Strandberg Computer Center Department of Physics University of California, Irvine Massachusetts Institute of Technology Irvine, California 05616 Cambridge, Massachusetts 02139 Andrew J. Kleinschnitz Frederick Tonge Philco Corporation Computer Center 3900 Welsh Road University of California, Irvine Willow Grove, Pennsylvania Irvine, California 95616 Edward D. Lambe Edward Turner Department of Physics Physics Department State University of New York at Stony Brook Washington and Lee University Stony Brook, New York 11790 Lexington, Virginia 24450

76 ,47): irTAIraTr"riv,vr-tr-',4547-17

,issekiewiltbaradtakswilitagite.ATimt 'el.iiiimegitititttettitetshaea461

Richard Walther Commission on College Physics Director of Research Educational Sciences Division Staff U. S. Industries, Incorporated Silver Springs, Maryland 20901 John M. Fowler Director Karl L. Zinn Center for Research on Learning and Teaching W. Thomas Joyner The University of Michigan Staff Physicist 1315 Hill Street Peter G. Roll Ann Arbor, Michigan 48104 Staff Physicist FILMED PRECEDING PAGEBLANK- NOT appendix j

Flow Diagram:"Weightlessness" by Arnold Arons

The foldout pages which follow containa complete flow diagram of a CAL drillrecitation uniton the subject of weightlessness. The unit was prepared on the COURSEWRITERsystem by Arnold B. Arons (Amherst College) at the Seattle Working Conferenceon New Instructional Materials in Physics (summer 1965). A brief description of theprogram can be found in Appendix C. It representsa first attempt at CAL programming by its author, and is presented here in flow diagramform not because it isa successful, useful, or tested example of CAL, butmerely to indicate to the reader what can be accomplished in the COURSEWRITERsystem. The following conventions have been adoptedin designing the flow chart: 1. Text enclosed in rectangular boxes is presentedto the student by the computer. It is typed out by the typewriter of the IBM 1050 instruc- tional terminal. 2. Possible student responses are enclosed in circlesor ovals. These responses are typed in by the student in answer to questions from the computer. The computer then compares theresponses with those stored by the author in the computer, and,on the basis of a match or lack of match, selects a reply from its repertoireas indicated on the flow chart. 3. In seeking a match toa student response, the computer often looks for the group of letters underlined in the ovals,rather than for an entire word. E.g., the responses motionor mouse will be recognized as equivalent, on the basis of the underlined key letters mo: Some of the key letters and words have been underlinedin the flow chart ovals; in other cases they have not because informationon the keying was lacking. 4. The diamonds containing interrogation marksrepresent branch points in the program. 5. In general, the flow path correspondingto the recognized, "correct" answer to a question posed by the computer is found above the

79 .^-7aF 77,/..MIFFTT11191111.1.9R r

branch point, while incomplete, unrecognizable, and incorrect answers are shown below the branch point on the flow chart. There are a few exceptions to this rule, necessitated by space considerations in laying out the chart. 6. A student who consistently gives the recognizedcorrect answer to all questions posed by the computer will follow the path indicatedon the flow diagram by the heavy lines.

80 sEcTion1I

Correct

A body of massin rests on the floor of an elevator. Letus suppose at first that the entiresystem is at rest Letts ex How many forces acton the body? Name o (Type a numeral.)

anything else If you are saying that there is a zero net forceon the body,you are of course You seem to be think- Please don't use the ing of too many forces. correct since it is not ac- Only one? If onlyone letter oh or eye. Type celerating. But we wish force were acting on the Try again. a numeral. to identify separate forces. body what would happen? Try again. Speed up Change. Increase Accelerate anything Faster and else Crest faster

This is not a full answer. Well "Motion" includes the the body No. The body has a would accelerate. case of uniform velocity Correct. net force on it. What Let's go back. which is not possible with go back. would have to happen? a single force acting. What would really happen to the body?

Pr 11 .

uaatikttttiliitiftsggbvhifttu'

2 Correct. I would you or describ other fo

Correct.

Let's examine these two forces. What is the direc- 1Name one of these forces. tion of this force? (Please use just one ward in your answer.)

'40 You are using words We still don't under- that we cannot re. stand you. Anyway cognize. Restate your one of the forces is answer. gravitational :the weight of the body. Correct. ne? If only one would you ere acting on the or descri hat would happen? other f

Speed up Change. Increase Accelerate Faster and faster

Correct. Letas go back. rwrimmoulm.101 Correct.

N-mg = ma ma = N-mg (N-mg))

Vas Now apply this state- Solve the equation OR, but we ment to the body in for the acceleration preferthe the elevator, replacing a. (Use the symbol a = N/m-g complete F(net) by the appropri. / for division and use (N -mg) /m form,a g ate expression contain- parentheses where re- (N-mg)/ m ing N and mg. quired. forfuture reference.

anythingt a = N-mg /m else

wimp Your answer is either In our nota- Watch the ne- You may have The correct rela- incorrect or not con- tion the cor- cessary paren- given the cor- tion is si4N.mgyin. sistent with the nota- rect answer thesis. Try re c t answer Type it in prac- tion we have adbpted. in N.mg=ma. again. but outside of tice. Please try again. o u r notation. Please try re- writing it. 4 Correct. Correct.

positive

t we Now suppose that If the sign of a the N is larger than is positive,in lete OK, except what direction Slide mg. What would that we pre- a= be the algebraic (up or down) / m ferthe word must the ele sign of the accel- ',positive. II eration? vator be accel- e. erating?

p

ct rela. HHowallaao an it be negative? Remember our mgym No. It must be N was indicated to be sign convention. in prac- accelerating lip. larger than mg. Try This is the alge- ward. That is tte again. braic sign of e. interpretation of What is its di. the alipbraic sigh rectionin space? Coirect.

[Suppose the ele. Correct. Think vator is seeder. about what this ating upward, impliesabout which is larger: ° the magnitudes themagnitude of the opposing of N or the meg. forces shown on nitude of mg? zero \ your diagram. (just use the ap propriate symbol as your answer.) Incorrect. What 4111111 is the accelera. tion of a body Incorrect. moving at uni. Try again. form velocity?

Incorrect. You would do well to Veview the discussion of No. Think of You must realise New- the net force ton's First Law and theconcept that the body is that must be of force. Start the problemover accelerating and after having doneso. You ar e acting.Try that the forces being signed off. again. areno longer balanced.

0 F F 777.517-, J:.

Correct. Correct.

F(net) = Ma N-mg, F(net) = ma Lets adopt the con- vention that the pos- itive direction is verticallyupward. Let "F(net)" denote the In terms of the sym- force and let "a" de- bols N and mg,which note the acceleration we shall regard asthe of the body. Write magnitudes of the two the expression for New.. forces,write a general ton's Second Law using expression for the net these symbols. force acting on the body: F(net)=

anything else

V V "111111111111111111111, ust realize You have the sign You seem not to Yes, except Yes, except that The Second wrong Observe know what to we usually e body is we wish to empha- Law is rating and theconvention: say. The alge- size the fact that writeit the Fine t)=m a. he forces positive direction braic expression it is the net force other way o longer upward. for the net force thatis equalto around. ed. is N-mg.If you ma:F(net)=ma. do not under- stand this, sign off and review the text.

0

F ,

Correct. V (3 Correct. tomosIP Eiyitation SECTION 1 weight

Remember we are des- cribing forces acting on What is the direc the body, not forces the tion of this force ? body exerts on some- (Please use just one thing else.Please t ry word in your answer.) again. anything else

Italage The other force is gra- vitational: the weightvassastsrmimma.. Its direction is Let tidens of the body. downward. weight of th by rag and ward push o Not specific enough. evator floor Try again. First draw a showing the acting 011 th Then EOB fo Correct. to verify diagram. floor, push, Correct support /

What is the direc. tion of this force? (Please use just one word in your answer.)

anything anything else else

It's upward. For the sake of further discussion, let us refer to i t as " the puk of the floor." SECTION

equal same et ttdenote the identical eight of the body y mg and the up- What is the rela- ard push of the el- What is the relation be tion between the vator floor by N. tween the magnitudes of magnitudes of the irst draw a diagram the two forces when the two forces when owing the forces elevator is moving up- the elevator is at mud at uniform velocity? cting on the body. rest. hen EOB for a slide o verify your iagram.

The opposing forces are equal in magni- tude since the system is not accelerating. gr-ig. -"'" r!7- ..r4trr - .7r

SECTION 1

Correct. Correct

It may be moving When N is either up or down larger than mg with uniform ve., (i. e. when the locity. Suppose elevator is ac- that N is smaller celerating up- than mg. In what wax1), does the direction must the velocity of the elevator be accel- elevator nec- erating? essarily have This is the sign to be upward. of a.What is its direction? anything else

V No. It must be accelerating downward. SECTIONg

Imagine that you are your- self the object in the eleva- tor. Suppose that the ele- vator is accelerating Whatfeeling or sensation do you have under these c ircurnp. stances? (Construct your an- swer to contain a reference to your sense of your own weight or heaviness in com- parison with being at rest.)

The velocity Check your answer against Remember that you are does not nec- the following phrasing: The accelerating upward. You essarily have elevator may be moving would feel heavier or ex- to be upward. downward with decreasing perience a sensation of in- speed and it might thus have creased weight. a downward velocity and an upward acceleration. _.

SECTION 3

Correct.

less, smaller rolNote that our sensation of weight is related not so much to the pull of the earth (mg), which remains constant, as it is to the Suppose that theelevator normal force N that the floor accelerates downward The on us. When N becomes 111NONIIMINIMMI. IIIIMIMMO 1MM. nimmivalue of N and the reading larger than its value when we on the bathroom scale are have a sensation of increased than the corre- weight. Suppose we are stand- -...... sponding values when we are ing ing on a bathroom scale as the at rest: Type the missing elevator accelerates upward. word in the following The reading on the scale will blank: . be than the read- ing when we are at rest. Type the missing word in the follow- ing blank: . anything else

The answer Incorrect. is larger. Ity again.

..cd1211111MIISISOMMILTVIUMMWSMIrm9X Correct. Correct.

less, smaller, less decrease decrease smaller light In the light of the Suppose we make the preceding discus- downward acceler- sion, how wouldyou ation still larger. describe yoursensa- Wh at h appens to N and tion of weight when thereading on the you are accelerating scale? downward? (Com. pare it with your sensation - at rest.)

anything else

No. Please try again. You would exper- ience a sensation of decreased weight. 71 Pr- ' .7.7777?--"I

cf

CorrecTio.. Correct.

What is the numerical These value of N when the stance downward acceleration What would be say is equal tog? (Note that the reading on "seas an acceleration equal the bathroom lessne to g implies free fall.) scale if the el- (depot (Go back to your form- vata were fall disap ula if necessary.) lag freely? at all. has ch

Please try again, No. N must be equal No. Please The scale reading typing a numeral tozero since an accel- 4111111 try again. must be zero since if you did not do eration equal to g im. the platform is not so. plies free fall with no exerting any force opposing forces. on your body. 8802Tos3

41

Correct.

N, up normal floor push These are the circum- stances under which we Is it possible for a body to be accelerated say we experience a downward with an acceleration of magni- "sensation of weight- tude larger than g? What must be done to lessness." Our weight make this possible? What sensation would (denoted by rag) has not you experience under these circumstances? disappeared or changed Take this question on your own. This is at all. What is it that the end of problem ele. Please sign of or has changed? go to another problem.

You did not match The upward force our vocabulary. exerted on us by the Please try again. floor has changed. When this force (N) becomes zero, we experience a sensation of weight less- ness.