dergraduates in public institutions now average $1,560 a year and in private colleges the present annual average is $2,370. Thus, the computing expenditure we are considering is about 4 percent of present annual cost.

Finally, a collective assessment of the value of computing to the national economy and welfare is represented by the expenditure of business and government for acquiring and using computers. Appendix I shows the historical trend-for comparison purposes, in 1965 about $2.4 billion was spent for new machines. It is estimated that the salaries and related overhead of the programers and operators for existing computers more than equaled that amount. Consequently, total expenditure was more than $5 billion in 1965. Thus, the educational expenditure estimated for 1971-72 is less than 8 percent of all 1965 computing expenditures. The growth rate pictured in Appendix I guarantees that the educational expenditure will be much less than 8 percent of the actual computing expenditure in 1971–72. What we are saying, then, is that university and college administrators must recognize education in computers as a pressing need and opportunity. It is an opportunity that can be grasped successfully for about a 4 percent increase in their operating budget. This is no mean feat in times of rising costs in all other areas of their operation. But a 1 percent rise might be possible if the other 3 percent came from Federal support. Certainly such a joint effort is essential if computer education appropriate for this country is to come about.

APPENDIX B

SOME FACTS OF LIFE ABOUT COMPUTERS

The mode of using computers has changed steadily through the years. In the earliest days of computers, each user took his program individually to the machine and used the computer either until his problem was solved, or until he ran out of assigned time. This is no longer feasible except in the use of obsolete computers which have been replaced but not discarded, and when one considers maintenance and space for such machines, it is of dubious merit. One can learn something about hardware and diagnostics by maintaining a computer, but one learns nothing about computer usage by having the computer physically accessible.

One of the first advances in adapting computers to easy use was the open shop together with batch processing. Open shop operation means that anyone who follows specified rules can get a program run, not just a selected group of programers. By batch processing we mean that the programs and data for a lot of jobs which various people want done are put on a magnetic tape and run through the computer in sequence. This means that all programs to be run must conform to certain rules, and use the input and output facilities which are provided for all. All these functions are implemented by a small amount of additional hardware and a large executive or system program to manage the operation automatically.* Batch processing can cut down the turnaround time, the time between handing a job in at a computer center and getting an answer back, to one or two hours.** As computers have come to be used by more and more people for a greater variety of jobs, even this may be too long to wait for an answer.

A recent development which makes computers more efficient and more flexible in use is called multiprograming. The flexibility is obtained by having the computer take up tasks in order of their ease or brevity. This is similar to a garage mechanic's having a 5-hour job but taking on easier 5- or 10-minute jobs as they come in. By interrupting the larger job periodically,

*Programs of this kind become an integral part of the computer to users, and so are often called "software" as a contrast with the hardware. The other computer operating schemes mentioned in the remainder of this appendix are also implemented by a hardware-software system, not by hardware alone.

**By use of a special system at the Case Institute of Technology, turnaround time for simple student problems has been reduced to 5 minutes or less.

more customers are satisfied and no one must wait for a very long time. In multiprograming the computer can leave a long job partly done to take on other, shorter ones, then return. This procedure also leads to greater efficiency. Without multiprograming, the entire expensive computer system can be held idle if processing is delayed for any reason; for example, if a new input tape must be mounted during the course of computation. This wastes both time and money, and computer time can be worth as much as a thousand dollars an hour. With multiprograming, another job, or part of a job, can be started (or even completed) during these necessary interruptions.

With multiprograming it is possible to use in one computer many controls and many arithmetic units. This is called multiprocessing and permits several jobs to be done simultaneously.

Another recent improvement in computer organization permits many users to have access to the machine simultaneously. This is called multiple access. Instead of having one line of jobs coming in one door, there are many doors with jobs coming into whichever doors are most convenient. The computer now cannot stand by one door, but must look all around. Thus there are many input terminals. For instance, at Dartmouth and in Project MAC at MIT, a number of computer users have keyboards by means of which they can call on one central computer.

When there is multiple access to a computer, the computer must decide which input to attend to. This depends not only on what the computer decides is efficient, but on the requirements of the inputs themselves. In some cases, for example, those involving data transmission from distant. cities, the information must be handled when it is received. In other instances semiautomatic readout of information (as from satellites) must be handled periodically in order to avoid storage overload, but the computer is more or less free to choose the time. In yet other cases, high-volume inputs such as punched card readers must be serviced very frequently in order to avoid pileup.

It is possible to have multiprograming without multiple access, but providing multiple access efficiently requires multiprograming as well. Most computers do not yet have multiple access, but the newest generation of large machines is well adapted to multiple access. Both multiprograming and multiple access permit increased efficiency of computing facilities and produce better service for more users. We do not yet know what the increase in efficiency will be.

Another rapidly changing feature of computer usage is in input and output equipment. In analyzing data, computers must be able to accept input in forms other than magnetic tape. In some cases they must be able to pick up readings from measuring instruments. In processing photographs of the tracks in bubble chambers or photomicrographs of human chromosomes, computers must be equipped with something like a television pickup device. Using this, the computer must be able to pick up data from different parts

of the picture at different times, parts chosen on the basis of what the computer has already found in the picture.

Modern computers have also been equipped with special output devices which can draw pictures as well as with special input devices which can read data from pictures. By programing a computer to draw a sequence of pictures, each differing a little from the previous one, a computer can be made to produce animated movies.

Sometimes it is desirable to obtain a diagram from a computer output without taking a picture and waiting for the picture to be developed. This can be done by storing the output numbers from the central computer in the memory of a small auxiliary computer. The auxiliary computer can then draw pictures on a cathode-ray tube (which is like a TV picture tube), pictures specified by the numbers stored in its memory.

The interaction between man and machine is an essential element in many modern uses of computers. The computer types out a text, or draws a picture, or places packages for minimum wire length, or calculates the deflections in a mechanical structure, and a man observes the result and makes alterations to correct defects or to improve performance. Multiprograming, multiaccess, and peripheral computers and visual displays are important elements in making such interactions between man and machine quick, easy, and efficient.

APPENDIX C

COMPUTER LANGUAGES

Any computer is built to respond to a repertory of instructions which cause the machine to perform arithmetical, logical, and input and output operations. These instructions, which are built into the computer, are called the machine language of the computer. The machine language of the computer may consist of two or three hundred (or even more) instructions or words.

The machine language of early computers was simpler though less powerful than that of present computers. And all programing was done in machine language.

Today, the majority of people who use computers do not use or know machine language. They write programs in some symbolic, simplified language which is adapted to the problem they wish to solve. The computer is then used to compile a machine language program, which is then run on the computer. The computer operates under a complicated systems program which controls the programs used to translate from symbolic, useroriented languages into machine language, provides diagnostic printouts when a program fails to compile, and makes it easy to handle input and output.

The best known symbolic language is FORTRAN (formula translation) which is adapted to numerical computation. FORTRAN is unnecessarily complicated for student use. Several special simple languages have been developed for student use, including MAD (University of Michigan), BASIC (Dartmouth), and CORC (Cornell). These are easy to learn. Perhaps even more important, they take less compiling time, and hence cut down on computation costs.

A large computer with a good operating system will handle programs in many special-purpose languages: languages to simulate economies or machines, languages to do algebraic manipulations, languages to design bridges and electrical networks, languages to produce musical sounds and motion pictures.

The provision of appropriate, adequate, and efficient languages is one of the most vital ingredients in the wider and more effective use of computers. This is a strong reason in favor of providing students and faculty with access to a large and powerful computer, rather than a small computer of limited flexibility and capability.