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The information for each of the 222 systems described in Chapter II has been subdivided into eighteen topics, permitting the data to be presented in an organized manner and simplifying the comparison of features of the different systems. The following paragraphs, paralleling the subdivisions of the systems descriptions of Chapter II, are an attempt to quantitatively analyze the data and show recent trends in the field of computing machinery. It is emphasized again that the information given in Tables II through XV in this Chapter is to be used with caution. The tables have been constructed only to show trends, permit limited comparison of systems and show the present state of the art. Information pertaining to a specific system should be obtained from the system description in Chapter II or directly from manufacturers and users.


The names of various types of computing systems existing in the United States stem from different sources. It would have been convenient if some system of classification and standard nomenclature had been established many years ago. The nomenclature could have incorporated the name of the manufacturer and model number, the nature or application of the system, or the name or location of the operating agency. However, a system of nomenclature was not established, resulting in an odd mixture of names for computing systems. Many computing systems bear the name of the manufacturing organization, for example IBM 704, HONEYWELL 800, NATIONAL 304, ILLIAC, and RCA 501. The names of some machines indicate the nature or purpose of the system, for example WESTINGHOUSE AIRBORNE, VOTE TALLY SYSTEM, CUBIC AIR TRAFFIC, WHIRLWIND and EDVAC. Other machine titles indicate the name of the operating agency, such as DYSEAC, SEAC, NORC, OARAC, ORACLE and ORDVAC. Some titles are indicative of the location of the system, such as LARC. The names of some machines are trade names like UNIVAC II and ET OM 125. There are some machines named after specific persons, as are ALWAC III E and JOHNNIAC. Arbitrary names, like GEORGE, also exist. Another trend in computing machine nomenclature has been to develop names which were contractions or pronouncable abbreviations of significant titles. Examples of this are EDVAC, for Electronic Discrete Variable Automatic Computer; MANIAC, for Mathematical Analyzer and Numerical Integrator And Computer; and ORDVAC, for ORDnance Variable Automatic Computer.


In the interest of national defense, the development of electronic computing systems could not wait until normal economic laws brought about the supply of systems through commercial demand. The Department of Defense supported research and development in the field of electronic digital computers to be utilized for rapid scientific computation on defense projects.

The world's first electronic digital computer, the ENIAC designed and developed by the Moore School of Electrical Engineering of the University of Pennsylvania, for the Ballistic Research Laboratories was placed in operation at the Aberdeen Proving Ground in January 1947. Many early electronic machines were manufactured at educational institutions such as the Institute for Advanced Study, MIT, Harvard and the Universities of Pennsylvania and California. Parallel research was performed by industry, and by 1950, large scale digital electronic computers were being delivered commercially. At the present time mass production of large scale systems is well underway. Several thousand large scale systems of various types have been mass produced, and thousands axe on order. Table I shows the manufacturers of all the machines described in Chapter II and Table II shows the approximate quantities of these systems which have been produced.
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The installation of the ENIAC, at the Ballistic Research Laboratories of the U. S. Army Ordnance Corps marked the beginning of the widespread use of electronic computing machines. Since the advent of the ENIAC, a large expansion has taken place in the computer field. Investment rates in computing equipment in the United States have risen from ten million dollars per year in 1953 to one hundred million dollars per year in 1956. Present expenditures for computing equipment has passed the billion dollars per year mark.

Almost every commodity industry such as oil, steel and rubber is utilizing computing equipment for both scientific and commercial applications. Service industries, such as banking, transportation, and insurance have applied large scale systems toward the solution of problems in the fields of accounting, reservations control, and bookkeeping. Manufacturers have used computing systems for design engineering and scientific research. Many systems are being utilized for inventory and stock control. The determination of manufacturing plant location and stock parts storage are being made by linear programming methods. Electronic computers are being utilized by the construction industry for design and location of structures and road nets. Many digital computers form a part of closed loop industrial process control systems.

Many problems require the processing of large quantities of data, such as is obtained from missile tracking, telemetering, mineral deposit prospecting and record keeping. The use of electronic computing equipment permits the processing of large quantities of such data over relatively short periods of time.

Many "on-line" applications of both general and special purpose computers are being made. These control applications include such examples as control of wind tunnel testing and continuous-flow manufacturing. Computers are being used for aircraft and missile fire and flight control, both as ground based and missile borne systems.

A discussion of applications of specific systems will be found under the sub-heading "APPLICATIONS" in the various computing systems descriptions given in Chapter II.


Internal Number System
Many types of number systems have been utilized for the development of logical designs of computing systems. Among these number systems are the straight binary, octal, binary coded decimal, straight decimal, sexadecimal, biquinary, binary coded alphanumeric, and binary coded decimal (excess three). Of 187 different relevant systems, 131 utilize a straight binary system internally, whereas 53 utilize the decimal system (primarily binary coded decimal) and 3 systems utilize a binary coded alphanumeric system of notation. Of course, in nearly every computing system, information is ultimately handled in binary form, particularly in storage and in arithmetic units. The primary method of storage exploits the inherent properties of material media, such as semiconductors, and ferroelectric and ferromagnetic materials. The state of conduction or the polarization of ferroelectric and ferromagnetic materials determine the nature of the information which is stored or being processed. Decimal digits are handled as groups of four bits, or tetrads. Alphanumeric data usually requires the use of six bits, permitting 64 different symbols. Some systems utilize seven bits for expressing a single character, permitting 128 different characters, or may utilize a single bit as an "odd-even" check bit. Programmers and coders preparing problems for solution on these systems may work with decimal or alphanumeric notation and need not be concerned with the binary coding performed automatically by the machine.

Word Length
The selection of word length for computing systems is based upon many considerations. For information words, the precision required for the solution of problems may be the major consideration. For instruction words, word space must be allocated to the address of the operand (or operands for multi
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address codes), the command, and perhaps spares, tags, or check digits. For example, the ORDVAC utilizes 39 bits plus sign for an information word. One-half of a word, or 20 bits, is subdivided into a 12-bit address portion (for 4,096 high speed storage locations), a 6 bit command portion for 64 commands, and a 2- bit spare digit portion for special applications and versatility. The variation of word length among existing systems is rather wide. Table III shows the word lengths of the 222 systems described in Chapter II, in ascending order of magnitude. The average or nominal word length for fixed word length machines is approximately 40 binary or 12 decimal digits.

Number of Instructions Per Word
In many systems the machine word structure permits several instructions to be expressed by a single word. Of 171 systems,107 were reported as operating on a one instruction per word basis and 28 were reported as operating on a two instructions per word basis. Several systems required two words to express a complete instruction and, in some systems, several instructions could be expressed by a single word, at the option of the programmer.

Arithmetic System
Most of the earlier machines operated on a fixed point arithmetic system. The binary or decimal point was arbitrarily fixed at either the right or left end of the number. For some systems a centered decimal point permitted the direct expression of whole and fractional parts of numbers. Scaling is required, for example, when a decimal or binary point is located at the left end of a number, in which case all quantities must be scaled between the values of minus one and plus one.

Many of the later machines were manufactured with built-in automatic floating point equipment, permitting numbers to be expressed as fractional parts and exponent parts. The exponent usually is a power of two or ten. Floating point circuitry was added to many of the older systems. A review of this sub-heading in the systems descriptions found in Chapter II and an examination of Table III will show the distribution of fixed and floating point equipment.

Instruction Type
Internally programmed automatic computers require that part of the instruction word be devoted to the address (or addresses) of the operand (or operands). The question of how many addresses are to be incorporated into a single word has been answered in many ways. In single address machines, the address of one operand is given in the address portion of the instruction word. In two address machines, the address of two operands are given, for instance the addresses of the minuend and subtrahend are given for a subtract instruction. For three address machines, the address for storing the result, e.g., the sum, difference, product, quotient or square-root, is given. The three address machines usually refer automatically to the next storage location, in sequence, for the next three-address instruction word. Machines using the four-address instruction will express the location of two operands, the location for storing the results of the operation, and the location of the next instruction, all in one four-address word. In a 1 + 1 system of notation the address of an operand for the current instruction is given, along with the address of the next instruction to be performed. Coding for four-address machines is somewhat simplified, however, a more complex machine structure is necessary. The following table shows the distribution of different addressing systems among the types of computers described in the handbook.

        Instruction Type           Different Systems Using Given Type Instruction
        One-address                              116
        Two-address                               23
        One or two-address (optional)             13
        Three-address                             20
        Four-address                               7
        One-plus-one and one-over-one address      8
        One and one-half address                   3
        One or three-address (optional)            2
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One or one-plus-one address (optional) 2 One, two, or three-address (optional) 2 One, two, or four-address (optional) 1 Modified three-address 1 Three or four-address (optional) 1 Variable up to five-address (optional) 1 Total 200

Instruction Word Format
Most systems require adherence to a specific format or sets of formats for preparing coded instructions, in the machine language. The instruction word format thus outlines the form in which the instruction is prepared. An accounting must be made of each digit or character of the instruction word.


Operation Time
Since the primary function of an arithmetic unit in any computer is to perform repetitive arithmetic operations rapidly, the time required to execute an add instruction or a given sequence of arithmetic or logical instructions, is extremely important when selecting a computing system for a specific application. Tables IV and V were prepared to show at a glance the general state of the art with respect to arithmetic speeds. It must be emphasized that the values stated in the table are on an "as reported basis". The reader is reminded that the tables must be used with caution, since many clarifying or related remarks have been omitted for the sake of simplicity. Refer to the system descriptions of Chapter II for further detail.

Table IV shows the approximate relative order of add time when including the storage access time. In many systems, it is not possible to determine the time required for one addition without considering storage access. This may be due to the fact that in many types of operation, sums may form in an accumulator as the addend is brought from storage, hence access time may be inseparable from add time.

Construction of Arithmetic Units
Most of the computing systems described in this report utilize tubes or transistors as the basic driving element in the arithmetic unit. Several systems utilize magnetic cores in the arithmetic unit. Gating for arithmetic and logical units is most usually performed by diodes, transistors, or vacuum tubes. A review of the construction methods used in arithmetic units is discussed under this topic in the systems descriptions.


An extremely diverse and dynamic field of interest in the study of computing systems is the subject of storage devices. Many ingenious devices, utilizing the ability of various material media to store or record energy transformations, have been devised. Early forms of storage involved mechanical deformation of material media. These are exemplified by cams, springs, gears, music box cylinders, perforated player piano rolls, code wheels and perforated paper tape. All these storage devices required the movement of large masses of material and consequently long access time was inherent. The capacity, in terms of stored information per unit volume of material, was very low.

During World Wax II, the search for more rapid access storage devices led to the use of the vacuum tube. The two states, that of conduction and that of cut-off, permit information storage on a binary basis. This system, as was used on the ENIAC, proved effective from an access time consideration, however, the system was extremely bulky and required thousands of electronic vacuum tubes for a storage unit consisting of only 20 words of 10 decimal digits each.

Chronologically, the next development was the use of acoustic delay lines of mercury and quartz. A transducer at each end of a length of these materials permits energy conversions and allows the storage of information in the form of high frequency (e.g. 8 megacycles/sec) pulse packets. The information is
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continuously recirculated. Information is inserted or read out through the use of standard gating techniques. Among the computers utilizing acoustic mercury delay lines are the DYSEAC, EDVAC, ELECOM 725, SEAC and UNIVAC I. Quartz acoustic delay lines were also used. Other types of delay lines used for storage of information are the magnetostrictive and the electromagnetic or distributed L-C network. See Tables VI, VII and VIII, which list the computing systems utilizing delay line storage units. Although in operating principle there is no difference, it is necessary to make a distinction between a delay line used in a storage loop in which information is continuously circulated, and a delay line used only for purposes of timing the arrival of information at selected points for performing various logical operations. In the latter, the function is delay, or temporary storage, rather than permanent storage. Since delay lines store information serially as a train of electrical or sonic pulses, average random access time is limited to half of the time length of the delay line plus the time equivalent to one word length. Because of the serial nature of the system, delay line storage units are limited in speed. Notice how the delay line types of systems lie near the bottom of the Access Time of High Speed Storage, Table VI.

The search for shorter access time brought about the development of the electrostatic storage unit, also called the cathode ray tube storage device. The material medium in motion was now limited to electrons, i.e., in beams and on charged areas on the screen of a cathode ray tube. These charged areas behaved somewhat like an array of charged capacitors. Selection of storage locations and the transfer of information was efficiently performed by an easily deflected pencil or beam of electrons which was used for both writing and interrogation. Parallel transfer, in which all digits of a given word are transferred simultaneously, became possible with this type of storage system.

The electrostatic storage system, with the inherent problems associated with high accelerating voltages, screen imperfections and other tube failures, has all but yielded to the utilization of magnetic cores for the storage of information. A 32 x 32 array of ferrite cores, which might constitute a typical storage plane, may measure only a few inches on each side. The cores are placed at the intersection of the wires of a mesh, and a third winding may be threaded through all the cores for sensing stored data. The storage takes place in the form of magnetically oriented molecular or atomic dipoles which retain their orientation upon removal of the magnetizing force. Many manufacturers intend to provide computing systems with large capacity core storage units. Advances have been made in the use of perforated ferrite plates and magnetic films deposited on glass as a magnetic storage unit. Two such systems, the LINCOLN TX 2 and the UNIVAC 1107 utilize thin films. The storage principle is the same as for magnetic cores. Table VI shows the access time of high speed storage units in their approximate relative order of magnitude for the storage units used in various computing systems. It must be emphasized that the question of precisely what constitutes access time cannot easily be resolved unless a common understanding as to the definition is reached. In the usual sense, one may consider access time as the elapsed time between the initiation of a command to transfer an item of information, usually one word, from one address in the storage to another designated register, and the complete arrival of the item at the designated location. In many systems, particularly serial storage units, access time depends upon the time location of the word in the serially circulating group of words at the instant the transfer command is initiated. For this and other reasons, much misunderstanding can arise in the consideration of access time. the data presented in Table VI should therefore be considered to be approximate and should be used with caution.

The capacity of high speed storage units has risen during the past few years as rapidly as access time has diminished. Table VII shows the capacity of high speed storage units in terms of numbers of words and word lengths, arranged in relative order of magnitude of equivalent binary capacity.

Rapid access storage of limited capacity is usually supported by a larger capacity storage unit for a well balanced storage system. This permits the transfer of large blocks of information from the rapid access storage unit to the large capacity storage unit for use at another location or time in the
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computation process. The most prevalent devices for auxiliary storage of this type are the magnetic drum or the magnetic disc. The access time for large blocks of information is of the order of tens of milliseconds for most magnetic drum or disc units. Many computing systems utilize magnetic drums or discs as the primary storage unit. Several systems utilize large capacity drum or disc units particularly for commercial type applications, such as payroll, stock inventory, and personnel records where access times of the order of microseconds are not required. Table IX shows the capacity of various drum or disc storage systems currently in use. It should be remembered, when glancing at Table IX, that although an attempt was made to show maximum capability, additional drum or disc units can be attached to some systems. Many systems employ magnetic tape as a medium of storage. Although access time is relatively long because of its inherently serial nature, a large vole of data can be stored on tape with a high packing density in terms of data units per unit volume.

The characteristics of a storage device, namely, capacity and access time are two aspects of a storage system which come under consideration when designing or using a machine. The user or manufacturer of a system, at times, can trade capacity for access in the sense that under certain conditions he can accomplish an equivalent amount of computation with a large capacity, somewhat longer access time system as with a small capacity, short access time system. This is the old problem of trading time for space or vice versa. There are limits to this however, for example, when access time approaches the order of milliseconds, computation is seriously slowed down. Since large capacity and short access time are features to be desired, let us examine a quantity determined by the expression:

1og10 (Capacity in Equivalent Binary Digits/Access Time in Seconds)

In early storage devices, such as music boxes and signal coding equipment, this number is of the order of two to three. Relay storage units have a number of the order of four or five. Tube registers of the ENIAC vacuum tube accumulator storage type, enabled this figure to be as high as 6.3. Magnetic drum storage units are in the region of 6 to 7. Acoustic delay line storage systems show that this figure is in the range 8.6 to 9.6. The cathode ray tube storage (electrostatic) raised the figure as high as 10.79. The magnetic core storage unit permitted an increase of this figure to over 12. Thin films have now arrived d on the scene as a practical storage medium. The following table shows the growth, or increase of this number, as development of computing system components progressed:

                                   Approx. Median       Approximate Year
       Storage Device          Log10 Capacity/Access     of Development
       Early Mechanical             2 - 3                   Prior to 1930
       Electromechanical            4 - 5                     1935
       Vacuum Tube                  5 - 6                     1940
       Magnetic Drum                6 - 7                     1945
       Electrostatic (CRT)          9 - 10                    1950
       Static Magnetic (Mag. Core)  9 - 12                    1955
       Thin Film                   10 - ?                     1960
Table VIII is a tabulation of the Log10 Capacity/Access figures for the high speed storage units of various computing systems in approximate relative order of magnitude.


The above discussion on arithmetic units and storage devices have shown the great strides that have been made in these fields during the past several years. Arithmetic operation and storage access times have decreased and storage capacity increased. Yet, the communication link between the person and the machine still presents a major problem. Paper tape and cards, inherently bulky, are prevalent and relatively slow, particularly for scientific applications. The main convenience afforded by cards, particularly in commercial systems, is their capability of storing a complete item of information on one card, which may be handled separately or as part of a group, such as data on an insurance policy, a
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payroll line, a stock item, a set of corresponding test data, etc. There is no doubt that punching cards is a slow process. Paper tape perforators are also relatively slow in the sense that the data to be punched is usually available at a rate faster than paper may be mechanically perforated, although high speed perforators are being developed and are finding application. Keyboard input systems are useful primarily for the manual insertion of words for test or other special purposes.

In addition to paper tape and card readers and punches, many systems utilize high speed printers and magnetic tape units as a medium of input and output. Magnetic tape output still requires a conversion from magnetic tape to cards or printed page in order that the information be available to operating personnel. However, since human intervention is gradually being reduced, the use of magnetic tape for input, output and storage is increasing rapidly. The prevalence of various input-output media for the 222 computing systems described in this report may be determined by examining the data under the sub-heading "INPUT" and "OUTPUT" in the systems descriptions given in Chapter II.

One method for decreasing machine time spent waiting for reading and writing instructions to be carried out is to provide for concurrent operation. The later machines have built-in circuitry for permitting reading and writing to take place during computations. Apparently the only stipulation is that a given storage location does not become involved in reading, writing and computing at the same time. Many machines, for example, compute while punching and reading cards or while "looking-up" information on tape. Others fetch the next instruction out of storage while performing an operation.

Another method of reducing reading and writing time and to avoid a large amount of lost time when a large amount of machine reading and writing is necessary is to provide for reading and writing on a high speed device such as a magnetic tape or wire unit and allow "conversion" to another medium to take place off the machine at "leisure". Magnetic tape-to-card converters and inverters are becoming available as well as magnetic tape-to-printed-page converters. Paper tape and cards may sometimes be considered as forms of storage, since information recorded on these media may be returned to the machine. Considerable progress is being made in the field of printed page readers. See, for example, the IBM 1401 System.

It is often necessary to have computing systems capable of communicating with one another directly. For this reason, input-output media conversion is becoming quite prevalent and large conversion equipment is rapidly becoming available. Input- output schemes are so many and varied, that a complete treatment of this subject is beyond the scope of this report.


There are many impressions which come to mind when one examines such things as transistor, tube and crystal diode counts in a large scale computing system. There is a tendency to visualize a large, sprawling system when the tube count is high. There may be large tube-changing programs based on experience in effect on these large systems. Failure rates, preventive maintenance techniques, tube life problems, design limitations and tube specifications must all be considered on a systematic basis when the tube count is high. Tube count and a knowledge of tube operating characteristics may yield an approximate estimation of some of the problems that may be encountered in the operation of the system. Table X shows the approximate number of tubes utilized in some of the computing systems described in this report. Maintenance of transistorized systems has become somewhat simpler than maintenance of vacuum tube systems. Power and space requirements for transistorized systems are considerably reduced.

The servicing of a large electronic computing system can be materially simplified by reducing the number of tube types in the system. Standards for tube testing need apply to fewer tube types and tube checking can be further systematized due to a reduced number of test variations. Of course, a test specification or test criterion must be established for the most severe application for which the particular tube type will be applied. A severe or special circuit requirement may be better served through
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the use of another tube type. This, then increases the number of tube types. Normally, it is, possible to select a type of tube for a group of duties. In a given system, for example, a certain type is selected for driving, for voltage amplification, for flip-flop circuits, normally "on" or "off" conditions, etc. This establishes a number of tube types for a given system and any modification of the system usually should include this "tube type" complement.

The question of crystal diode reliability, diode testing techniques, and diode logical network design, such as individual clamps versus wired plug-in units, become subjects of interest when diodes are utilized. The quantity of diodes in a given computing system may be indicative of the nature of the servicing problem, but only when the failure rates, life and circuit demands placed upon the diode are known. To some extent, malfunctions due to diodes can be aggravated by elevated temperatures. The printed circuit logical package, containing a specific array of "And" and "Or" gates have become the most prevalent means of fabrication. The extent of crystal diode use is shown in Table XI.

Many recently developed systems utilize transistors for driving, switching (gating) and other logical functions. Reduced power and reduced space requirements are advantages of these systems. The question of reliability is rapidly being resolved, as printed circuits and packaging techniques continue to be improved. Table XII shows the quantity of transistors utilized in the various computing systems described in Chapter II.


The question of what type of checking features should be incorporated into a given general purpose computing system is still being tossed about by various manufacturers. The type of built-in check varies from manufacturer to manufacturer and from system to system.

It is usually possible to check all machine calculations by programming techniques. A well designed system can proceed for many hours without a malfunction. If this is the case, it is entirely possible that the installation of a checking system can do more harm than good since the checking features can malfunction and cause an alarm or stoppage when a machine malfunction has not occurred. For example, the second unit of twin arithmetic units can malfunction, the comparer of a redundancy checker can malfunction, or a forbidden pulse combination decoder can malfunction, all. yielding false indications of a machine malfunction. For those systems which do not have built-in checking circuits, the operator or programmer must program a check or the output may be reviewed.

About 87,% of the 222 computing systems reported utilize some form of automatic built-in check. A redundancy or duplication check is used in about 8% of the systems. Some type of overflow or exceed capacity is used on about 23% of the systems and an odd-even parity check in one form or another is used on 50% of the systems. Interesting to note here is that in 1957 only 20% of the systems bad a form of parity check. Various kinds of transfer checks are used on 19% of the systems. Approximately 28'% of the systems established a checking system by detecting pulse combinations which are not supposed to occur anywhere in the system. Forbidden pulse combinations checking stations are scattered around the system, e.g. in memory transfer points, recording stations, reading stations, etc. The various names that have been applied to this type of check are forbidden pulse combination, unused order (instruction), unallowable order digit, improper operation code, improper command, false code, forbidden digit, non-existent code, and unused code. There is a distinction to be made between the terms order, instruction, and command. The preferred definitions are given in the glossary of computer engineering and programming terminology, Chapter IV. The following table shows the approximate distribution of checking methods in the systems described in this report. Many systems utilize more than one check technique.
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          Distribution of Automatic Checking Schemes Among 222 Different Computing Systems

     Parity (arithmetic, transfer, storage, recording)                        99
     Overflow (underflow, exceed capacity, divide by zero, divide overflow,   47
      oversized quotient)
     Transfer (echo, compare, validity)                                       38
     Non-existent command                                                     19
     Non-existent memory address                                              15
     Redundancy (equipment, operations)                                       15
     Character code (non-numeric, illegitimate char, "all ones", sign)        14
     Forbidden pulse combination (general)                                    14
     Arithmetic (Modulo 3, 4, 9, 25, residue)                                 13
     Timing (clock, synchronism, jitter)                                      12
     Count (hole, address, row, block, word, random error)                     9
     Non-existent device
     Miscellaneous (instruction-data, logic, inactivity, 
         unwanted digit, free time)                                            7
     No built-in check                                                        26
     Not reported                                                             22


Important aspects of computing systems are the physical factors of power, space and weight.

Power requirements may very well dictate the physical location of a large computing system within a building, particularly when the power required is in excess of 50 Kw. For most systems, however, the power is brought to the most favorable computer location from the point of view of personnel accessability for operation and servicing. Table XIII shows the power requirement of various domestic digital computing systems, operational or about to become operational in the United States.

An interesting figure might be the relation between the number of tubes utilized in a computing system and the power requirement. In order to determine whether or not a consistent tube to power ratio could be established, the ratio was determined for the computing systems for which the data was available. For the vast majority of computing systems the tube-power ratio is approximately 710 tubes/kilowatt. A sample taken of transistorized systems shows that the ratio of transistor quantity to power is about 6,000 transistors/kilowatt.

The problem of space requirements has been solved in so many ways it is impossible to determine a consistent relation between space requirement and any other factor. Large computing complexes have been installed in areas ranging from a corner of a basement to an entire floor of a large building. The pictorial coverage of computing systems and the space requirements discussed under the sub-heading "POWER, SPACE, WEIGHT, AND SITE PREPARATION" in the systems descriptions of Chapter II give the space requirements of the computing systems described in this report. The dimensions of various components of utilized systems are important when considering clearance in rooms, passages, doorways and elevators.

Air conditioning requirements vary considerably from system to system. Air conditioners for computing equipment may utilize water to absorb the heat from circulated air, use a secondary loop of air, force the heated air to the outside, or utilize an outdoor evaporator. The smaller systems circulate room air and depend on the ambient temperature to cool. Almost 100% of the power required by the system is dissipated in the form of heat and must be removed. The large systems usually require separate heat removal facilities. For many systems, humidity and dust control within the machine are required in order to maintain satisfactory operation.

The factor of weight can be important when the floor loading limits for distributed and concentrated loads are within the weight range of the computing equipment. Many systems may require reinforced or specially constructed buildings. Many items of peripheral equipment may cause concentrated loads in
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excess of maximum permissable concentrated loadings on some structures. Vibration and shock caused by some equipment such as tabulators and card punches can cause trouble in other components. Shock and vibration absorbing pads are required in such cases. When unitized construction is used, the weight of a single unit must also be considered when transporting and installing.

Many systems require extensive site preparations. Others may be "plugged in" to any convenient outlet. This topic is adequately discussed in the systems descriptions of Chapter II.


In almost any new and rapidly changing field there will be many instances in which an experimental prototype of a large piece of equipment will be built. This is the result of the normal course of events, namely, a feasibility study, a research effort, a development effort and a prototype construction. Mass production then occurs when the demand for systems is sufficient to warrant production in quantity.

A review of the sub-heading "PRODUCTION RECORD" will give an indication of the production status of various computing systems. The quantity produced, the quantity in current production, in current operation, and on order are given. Delivery times quoted show that immediate delivery is now possible for many computing systems. Table II shows the quantities of the various systems that have been produced. Information on unreported systems was considered proprietary by the manufacturer.


Perhaps the most elusive and intricate item considered in the systems descriptions of this report is the question of initial cost, blandly described as "approximate cost of basic system". Manufacturers are quite naturally quoting current prices for their respective systems. The "one of a kind" system usually includes all research, development, construction, overhead and sub-contracting costs. The "basic system" usually includes minimal input devices, the controls, the storage system, the arithmetic unit, and minimal output devices. All conversion equipment such as card-to-printed page (tabulators), card-to- tape, tape-to-card etc. are considered peripheral equipment, and both the quantity and type is dependent upon specific system application. These are not included in the cost or price of the basic system. Prices of these may be found under "Additional Equipment". In order to determine the cost of a given system, refer to the system description. Table XIV shows the approximate relative cost of various computing systems. No attempt was made to resolve or explain any discrepancies between prices quoted by manufacturers and those quoted by users. It should be remembered that users prices reflect old sales, rental rates were established by contracts written years ago, manufacturers are offering discounts on older systems, charging greater service rates for older systems, offering educational discounts, etc.

The methods of computing system or component acquisition include direct purchase at a fixed price, direct purchase on a cost plus fixed fee basis, continuous rental, and rental with all or part of the rental applicable toward purchase. Most forms of rental include servicing. Direct purchase can include a service contract. Rental rates are of the order of 3 per cent of the direct purchase price per month. The sale and lease policy of various manufacturers is given under the sub-heading "COST, PRICE AND RENTAL RATE" in Chapter II.

Table XIV shows the nominal price one may expect to pay for a basic system. For many systems, one might add 20 to 80 per cent for required peripheral equipment. Most prices include installation but not shipping costs. Some of the figures reflect prices which are not current and have not taken into account general price rises during the past several years. Some figures include initial service or some type of warranty. The figures quoted in Table XIV are for general consideration only, and axe not for purposes of acquisition. Indeed, many systems are not available, even at the price quoted, since the price stated is actually the construction "cost" to the owner.
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An attempt was made to discover whether a "system cost per tube" figure could be established. For the larger systems, the figure is of the order of 200 dollars per tube installed and for the smaller systems approximately 100 dollars per tube. However, a glance at Tables X and XIV will show that such a figure can be calculated with some difficulty. An attempt to determine a figure such as "cost per cubic foot" of electronic computing equipment would be equally difficult. Such exercises are left to the reader should such figures be of any interest.


Personnel problems have confronted computing system operators and manufacturers from the very outset, in all phases of computer research, development, manufacture, installation, operation, improvement and servicing. Various grades of skills are required in the fields of engineering, physics and mathematics. Each large system has a crew of engineers and technicians for improving and servicing and a group of mathematicians and operators for problem analysis, coding and programming. In the very small systems, all of these functions may be performed by one or two persons. The systems descriptions in Chapter II show various estimates made by manufacturers and operators of what the personnel requirements are or should be for various systems. The estimates, in some cases, do not show the personnel required for overtime, vacations, illness and training purposes. Just as in any application of manpower to machines, it is necessary to provide sufficient manpower so as to maximize machine utilization whenever possible. Many installations consist of multimillion dollar computer complexes. Such large capital investments must be utilized at maximum efficiency in order to avoid severe losses. Twenty-four hour operation increases the daily output and provides for more efficient utilization of capital equipment. Ultimate requirements for personnel depend to a large extent upon the nature of the application, particularly as pertains to coders, programmers and analysts.


The most discussed and most controversial issues in the field of computing machinery occur on the subjects of reliability, efficiency and system evaluation. The determination of the reliability of a system is difficult, primarily because of a lack of a common understanding or interpretation of the definitions of computer operating terms. What actually constitutes "good time" on a computing system? What is "down time", "scheduled engineering", "useful production and code checking"? An attempt has been made to provide working definitions of these and other terms in the revised Glossary of Computer Engineering and Programming Terminology given in Chapter V of this report. The very crude "Operating Ratio", as is used in the systems descriptions of Chapter II, is defined as the "Good Time" obtained on the machine divided by the total time one actually "Attempted (or Wanted) to Run" the system. The question arises as to where to put the time lost in scheduled engineering (preventive maintenance), since technically, one is not attempting to run the system during this period, yet the system is not actually "down". Many systems, are operated for 168 hours per week. The operating ratio for these systems would require that 168 be used as the denominator and the number of useful output hours as the numerator, yielding a much smaller (but perhaps truer) ratio than a system operated on an 8-hour 5-day week shift and using off-time for servicing. This latter type of operation may yield operating ratios of the order of .90 to 1.0 and give a false indication of reliability.

The question of how one determines the average error-free running period is also a difficult one. It may be estimated or calculated by actual counts of the periods of malfunction-free operation. It may be the period used as a guide by coders to prevent losses due to running for extended periods between obtaining output information, particularly where volatile storage media are being used. Mary questions regarding the subject of "RELIABILITY, OPERATING EXPERIENCE AND TIME AVAILABILITY" are answered under this subheading in the computing systems descriptions given in Chapter II. A search of the system descriptions under this subheading will reveal those installations which have computer time available to organizations outside of the operating organization.
BRL 1961, ANALYSIS AND TRENDS, start page 1037
Many computing systems are approaching the age of retirement and replacement. Constant improvements have already replaced many of the original components of a system. The next few years will see the retirement of many of the older systems. Such retirement may take the form of salvage of parts, use for educational and training purposes, or scrap. Many older models are available at reduced prices. A used computer market is developing. In accepting a used computer, one must be prepared to accept a few headaches. Table XV shows how long some models of computing systems have been in existence.


Under this subheading has been placed general information concerning specific computing systems which did not have a "place" in the previous fourteen subheadings. Included under this subheading are remarks concerning the pictures, information which arrived too late to be added to the system descrip- tion under a proper heading, special features of the system and other miscellaneous items of information. Under this subheading one will find what manufacturers and users considered to be the outstanding features and unique system advantages of the particular system. Under this subheading are remarks concerning the labelling,storage, shipping and protection from humidity, temperature and physical, electrical, fire or other damage of magnetic tapes.


The electronic digital computer field is a dynamic one. Plans for acquisition and improvement of systems and components are continually being made and modified. The plans of various operators and manufacturers are given under the subheading "FUTURE PLANS" in the systems descriptions of Chapter II. Interesting to note are the transitions to new systems being made by many users. "Second generation" (solid state) computers are now at hand.


A primary source of information concerning electronic digital computing systems is the operating organizations. The acquisitional and operational problems of one organization may have already been solved in one way or another by other organizations. Benefiting from the experience of others can be profitable, if only to avoid mistakes. Under the subheading "INSTALLATIONS" in the systems descriptions of Chapter II, a list of the owners and operators of specific systems is given in order that contacts between owners and. prospective owners may be established. Many co-operative "plans" have come into existence, under which owners or operators of specific systems have engaged in sharing computer experience. Many computer sharing contracts have been drawn and many computer centers have been established, offering computer time and personnel for the solution of customers' problems.

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