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H. CHECKING FEATURES

  The question of whether or not to include built-in checking
features in a general purpose computing system is still a rather
debatable issue. It is usually possible to check the results
by prograimning 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 feature can mal-
function and cause an alarm or stoppage when 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 mal-
function, all yielding false indications of a machine malfunction.
Approximately 25 of the 84. computing systems described in this
report do not have any kind of a built-in checking system. The
only types of checks open to the operators of these systems is
a visual or test check on print-out, a complete or partial re-
calculation of the results, a programmed check or a marginal
checking system to determine the reliability of the equipment.

  The remaining 59 computing systems of the 84. reported utilize
some form of built-in check. A redundancy or duplication check
on storage and magnetic recording is used on 8 systems. A twin
arithmetic unit performing calculations simultaneously is utilized
in 5 computing systems. Some type of overflow or exceed capacity
is used on 10 of the 84 systems and an odd-even check is used on
17 systems. Various kinds of transfer checks are used on 5 of   




TABLE X

NUMBER OF TUBE TYPES IN VARIOUS COMPUTING SYSTEMS

	NUMBER	SYSTEM			NUMBER	SYSTEM
	------	------			------	------
	40	WHIRLWIND-I		6	MAGNEFILE-B
	38	UNI-SCI (ERA l103A)	6	MANIAC-II
	35	IBM-7O1			6	TIM-II
	34	SEAC			5	ELECOM-50
	29	SWAC			5	IAS
	21	UNI-SCI (ERA 1105)	5	FER MARK-I
	20	ILLIAC			5	PEGASUS
	20	NORC			5	PENNSTAC
	19	EDVAC			5	ORDFIAC
	18	UNI-SCI (ERA 1101)	5	WEDILOG
	16	ENIAC			5	FLAC
	15	NCR-CRC-102D		4.	ALWAC-III
	15	UNIVAC			4	CALDIC
	15	UNIVAC-II		4	IBM-CPC
	14	DATATRON		4	IBM-604.
	12	NCR-CRC-102A		4	MAGNEFILE-D
	12	ORDVAC			4	MONROBOT-IlI
	12	RAYDAC			4	NAREC
	12	RCA BIZMAC		4	TECHNITROL- 180
	10	IBM- 702		3	BENDIX-G15
	10	IBM- 705		3	CYCLE
	10	MIDAC			3	LOG
	10	UDEC-I			3	MODAC-14014
	9	MELLON INST DIG		3	MODAC-1410
	8	BUR-El0l		3	NCR-303
	8	JOHNNIAC		3	OLIVETTI-GBM
	7	BAR-COL DEC DIG		3	READIX
	7	IBM-607			3	WISC
	7	IBM-650			2	FER MARK-Il
	7	LGP-30			2	OARAC
	7	MANIAC
	6	ADEC
	6	BENDIX- D12
	6	ELECOM- 100
	6	HAL RAY BROWN

			95%	1 Type		MANIAC-Il
			90%	1 Type		DYSEAC
			Over	85% 1	Type	ELECOM- 125FP
			95%	2 Types		ELECOM-125
			95%	2 Types		ELECOM-120A



TABLE XI

CRYSTAL DIODE QUANTITIES IN VARIOUS C0MPUTING SYSTEMS

	QUANTITY SYSTEM			QUANTITY SYSTEM
	-------	 ------			-------	 ------
	62,897	RCA BIZYAC		4,500	ELECOM-120A
	50,000	NORC			4,400	READIX
	50,000	TECHNITR0L -180		5,700	SWAC
	25,500	DYSEAC			5,565	HUGHES AAC MOD-III
	20,000	MIDAC			5,500	DATATRON
	20,000	NAREC			5,000	BENDIX-G15
	18,000	FLAC			5,000	UNI-SCI (ERA-1102)
	18,000	RAYDAC			5,000	FER MARK-Il
	18,000	UNIVAC			5,000	MODAC-1410
	18,000	UNIVAC-II		2,600	LOG
	17,000	IBM-702			2,585	UNI-SCI (ERA 1101)
	15,159	SEAC			2,200	BENDIX D-12
	15,000	WHIRLWIND-I		2,200	ELECOM-l00
	12,900	IBM-705			2,000	ELECOM-50
	12,800	IBM-701			1,600	TIM-Il
	10,000	PEGASUS			1,500	ALEC
	 9,500	UNI-SCI (ERA l103A)	1,500	MELLON INST DIG
	 8,500	NCR-CRC-102D		1,260	BUR-ElOl
	 8,000	NCR-CRC-102A		1,200	BAR-COL DEC DIG
	 8,000	EDVAC			1,200	LGP-30
	 7,200	ENIAC			1,000	CALDIC
	 7,000	OARAC			1,000	FER MARK-I
	 6,500	NCR-SOS			1,000	MODAC-14014
	 6,000	ORDFIAC			  500	MANIAC
	 6,000	PENNSTAC		  450	OLIVETTI-GBM
	 6,000	UNI-SCI (ERA 1103)	  580	MANIAC-Il
	 5,500	ELECOM-125FP		  550	WISC
	 5,000	ALWAC-III		  240	MAGNEFILE-D
	 5,000	ELECOM-125		  200	JOHNNIAC
	 5,000	UDEC-I			  200	WEDILOG
	 5,000	WHITESAC		  100	MONROBOT-IlI
	 4,600	IBM-650			   80	ORDVAC
					   40	MAGNEFILE-B
					    5	IAS



TABLE XII

TRANSISTOR QUANTITIES IN VARIOUS COMPUTING SYSTEMS

	QUANTITY	SYSTEM
	--------	------
	500 approx.	UNIVAC-Il
	100		RCA BIZMAC
	Model Stage	IBM- 608



the systems. Approximately 9 systems established a checking
system by detecting pulse combinations which are not supposed to
occur in the process of computation. 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.
These preferred definitions are given in the glossary of computer
terminology. The following table shows the approximate distri-
bution of checking methods in the systems described in this 
report.
	TYPE OF BUILT IN CHECK	NO. OF SYSTEMS UTILIZING CHECK
	----------------------	------------------------------
	Redundancy			 8
	Twin Arithmetic Unit		 5
	Overflow or Exceed Capacity	10
	Odd-Even-Parity			17
	Forbidden Pulse Combination	 9
	Transfer			 5
	Miscellaneous			 8
	No built-in Check		25


I. PHYSICAL FACTORS

  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 KM. 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. The air condition-
er power requirements are not included in these figures.

	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 computed for the forty
computing systems for which the data was available. Discounting
5 systems in which the tube to power ratio exceeds 150 tubes/kilowatt
and the one system in which the ratio is less than 50 tubes/kilowatt,
it may be said that for the vast majority of computing systems the
tube-power ratio lies between 50 and 150 tubes per kilowatt. The
exact average ratio of the forty systems reporting this datum is
110 tubes per kilowatt. Miniaturization of tubes and the use of
diodes and transistors will reduce this figure considerably.



                    TABLE XIII

APPROXIMATE POWER REQUIREMENT OF COMPUTING SYSTEMS

	KW	SYSTEM			KW	SYSTEM
	--	------			--	------
	174	ENIAC			12	PEGASUS
	168	NORC			11	IBM- 607
	105	WHIRLWIND-I		10	CALDIC
	100	UNIVAC			10	WISC
	80	IBM-701			10	NCR- CRC-102D
	80	UNIVAC-II		8	NCR-CRC-102A
	75	IBM-702			7	BENDIX-D12
	69	IBM- 705		7	IBM- CPC
	55	IBM-704			7	FLAC
	50	EDVAC			7	ELECOM-120A
	50	ORACLE			7	ELECOM-125
	50	TECH-180		7	ELECOM-125FP
	45	LOG			6	READIX
	45	UNI-SCI (ERA 1103A)	6	IBM-6014
	41	UNI-SCI (ERA 1103)	5	HAL RAY BROWN
	40	ALEC			5	ALWAC-III
	35	JOHNNIAC		5	MINIAC
	35	MANIAC			5	ORDFIAC
	35	ORDVAC			5	MONROBOT-V
	35	UDEC-lI			5	WHITESAC
	30	FERRANTI MARK-lI	4	MODAC-1410
	30	SWAC			3	CIRCLE
	30	RAYDAC			3	MELLON INST-DIG
	30	UDEC-I			3	BENDIX-G15
	28	lAS			3	ELECOM-100
	26	FERRANTI MARK-I		3	MODAC-404
	25	MANIAC-II		3	NCR-SOS
	25	MIDAC			3	OLIVETTI-GBM
	25	NAREC			2	BUR-El0l
	25	OARAC			2	MONROBOT-III
	22	UNT-SCI (ERA 1102)	2	WEDILOG
	19	ILLIAC			2	BAR-COL DEC DIG
	15	PENI'TSTAC		2	ELECOM- 50
	15	SEAC			2	IBM- 608
	15	U141-SCI (ERA 1101)	2	ELECOM-50
	12	DYSEAC			1	HUGHES AAC MOD-III
					1	LGP-30
					1	MAGNEFILE-D
					1	MAGNEFILE-B
					1	TIM-II


Included in the figure is all of the power dissipated in associated
circuitry, lost in transformers and otherwise radiated.

	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. Similar 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 Physical Factors gives a rough approximation of the space
requirements of the computing systems described in this report.
The dimensions of various components of unitized systems are
important when considering clearance in rooms, passages, doorways
and elevators.

	Air conditioning requirements vary considerably from system
to system. Air conditioners may utilize water to absorb the
heat from circulated air, use a secondary loop of air, to 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 the system. Almost 100% of the power required
by the system is dissipated in the form of heat and must be removed.
Practically every computing system from the desk size to the
largest must be operated in air-conditioned room. The large
systems usually require separate heat removal facilities. Crystal
diodes and transistors are particularly temperature sensitive. In
many systems humidity and dust control within the machine are
necessary in order to maintain satisfactory operation.

	The factor of weight can be important when the floor loading
for distributed and concentrated loads is within the loading
range of the equipment under consideration. Many systems may
require reinforcement or specially constructed buildings or wings.
Many items of peripheral equipment cause concentrated loads in
excess of maximum permissable concentrated loadings on some
structures. Vibration and shock caused by some equipment such
as tabulators and card punches can cause troubles in other compo-
nents. Shock and vibration absorbing media are required in such
cases. In unitized construction, the weight of a single unit is
a factor in transportation and installation.



J.	PRODUCTION RECORD

	In almost any new and rapidly changing field there will be
many instances in which one model of a large piece of equipment
will be built. This is the normal result of the usual course
of events, namely, a feasability study, a research effort, a
development effort and a prototype construction. Mass production  
can only occur when the rapid evolution of new concepts ceases
and the best characteristics have been obtained that the properties
and limitations of materials will permit. Of the 614 systems on
which production records were reported, 35 were single model
systems. In many cases, a second model will never be built,
since the ideas incorporated into the single system have long
been outmoded. Some manufacturers have built a single system
with the intention of production in quantity. This single
model is in current operation and several may be on order. Of
the 814 systems described in this report, some of the very large
commercial and business type machines have as many as 22 in 
current
operation. Some of the very large systems exist in the form of
1 engineering prototype with over 100 on order.

	Delivery time varies from six months for a small desk size
system to 56 months for the large sprawling computer complexes.
Reference to the production records of the computing systems
described in this report will yield some concept of the avail-
ability and prevalence of various systems.



K. COST

	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. Research and development may be ab-
sorbed by the first few models or spread out over many. The one
of a kind" system usually includes all research, development,
construction, overhead and sub-contracting costs. The question
of what is included under "basic systems" is immediately brought
to mind. The basic system includes an input device, the controls,
the storage system, the arithmetic unit, and the output device.
All conversion equipment such as card-to-printed page (tabulators)
card-to-tape, tape-to-card etc. are considered peripheral equip-
ment, 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. 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. For the
systems reported upon, cost figures range from $17,000 to $2,500,000.
More recent systems currently under development, may cost 5 to 6
million dollars.

	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
a 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 5 per cent of the
direct purchase price per month.

	Table XIV does show the nominal price one may expect to pay
for a basic system. For many systems one might add 20 or 50 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 are
only for general consideration and not for ordering purposes.
Indeed, many systems are not available, even at the price quoted.

	One might make many studies utilizing the cost figures of
Table XIV and relating them to other features of the systems.
Suppose we assume that all of the systems are balanced, in the
sense that nothing is placed in the computing system in excess,
or is overdesigned. For example, a large system usually has a
correspondingly large storage capacity and an equally costly
arithmetic unit, control unit and input-output system. One might
then speak in terms of the cost per bit of high speed storage
in terms of the cost of the entire system. If a large system
handles payrolls or inventories, and the number of references
or transactions completed per day could be determined, one could
determine total operating costs per day including depreciation
and establish the cost per transaction. In most applications,
however, the cost per unit of calculated output cannot be deter-
mined.

	An attempt was wade to discover whether a working figure
could be established by considering the "cost per tube" which
one might apply to other systems with some accuracy. For the
larger systems, the figure is of the order of 200 dollars per
tube and for the smaller systems approximately 100 dollars per
tube. However, a glance at Table XIV and Table IX and some
mental approximation will show that such a figure cannot be
calculated with reasonable accuracy. An attempt to determine
a figure such as "cost per cubic foot" of electronic equipment
would be equally inaccurate.



L.	PERSONNEL REQUIREMENTS

	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  


                     TABLE XIV

         APPROXIMATE COST OF BASIC COMPUTING SYSTEMS

	DOLLARS		SYSTEM
	-------		------
	2,500,000	NORO
	1,750,000	RAYDAC
	1,1400,000	UNI-SCI (ERA-ll02)
	1,025,000	UNIVAC-Il
	950,000		UNIVAC
	895,000		UNI-SCI (ERA-ll03A)
	850,000		UNI-SCI (ERA-los)
	750,000		ENIAC
	600,000		ADEC
	500,000		FLAC
	500,000		TECH-180
	467,000		EDVAC
	550,000		LOG
	550,000		PER MARK-I
	500,000		ILLIAC
	250,000		MANIAC
	250,000		UDEC-I
	225,000		MANIAC-Il
	225,000		OBDVAC
	206,000		ORDFIAC
	200,000		UDEC-Il
	180,000		QARAC
	150,000		CALDIC
	150,000		PEGASUS
	140,000		DATATRON
	140,000		NCR-303
	120,000		MODAC-1410
	100,000		ELECOM-125
	100,000		PENNSTAC
	 99,500		NCR- CRC-102D
	 97,000		ELECOM-120A
	 89,500		NCR-CRC-102A
	 86,074		MONROBOT-V
	 85,000		MINIAC
	 85,000		MODAC-404
	 85,000		MDP-MSI- 5014
	 70,000		CIRCLE
	 70,000		MAGNETRONIC RES
	 60,000		ALWAC-III
	 60,000		ELECOM-125FP
	 60,000		ELECOM- 100
	 55,000		BENDIX-D12
	 55,000		READIX
	 50,000		MAGNEFILE-D
	 45,000		BENDIX-G15
	 52,500		BUR-El0l
	 50,000 	LGP-30
	 25,000 	TIM-II
	 20,000 	MAGNEFILE-B
	 20,000 	WEDILOG
	 17,000 	ELECOM-50



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 progra.ziuing. In the very small 
systems,
all of these functions may be performed by one or two persons.
Reference to the systems descriptions of this report will show
various estimates of manufacturers and operators of what the
personnel requirements are or should be for various systems. The
estimates, in some cases do not reflect the need for personnel
availability for overtime, vacations, illness, and turnover 
purposes.
It was intended to obtain the number of full time persons of
various skills required to provide satisfactory operation of the
system. Just as in any application of manpower to machines, it
is necessary to provide sufficient manpower so as to maximize the
benefits of machine utilization. Many installations include multi-
million dollar computer complexes. A large capital investment
must be utilized at maximum efficiency in order to avoid severe
losses. Twenty four hour operation increases the output of the
system when integrated over the life of the system since the life
of a computing system is more of a function of time rather than
of use.

	Examination of the personnel requirements section of the
systems descriptions in this report will indicate the approximate
needs for a system of the type described. Information from
operating agencies usually will indicate the actual number of
persons required for operation and servicing. Since improvement
is a continuous function, additional personnel will be required,
including engineers and technicians. Manufacturers tend to esti-
mate the minimum number of personnel required to be in attendance
for various number of shifts of daily operation. Again, these
figures must be used only as a guide.



M. RELIABILITY AND OPERATING EXPERIENCE

	The most discussed and most controversial issues in the field
of computing machinery are the questions of reliability, efficiency
and system evaluation. The determination of the reliability of
a system is nearly impossible, almost purely because of a lack of
a common understanding or -interpretation of the definitions of
computer operating terminology. 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 Glossary of Computer Engineering and Programming
Terminology in this report. The very crude "Operating Ratio" as
is used in the systems descriptions is defined as the "Good Time"
obtained on the machine divided by the time one actually attempted
to run the system. Here again, the question is where to put the
time lost in scheduled engineering (preventive maintenance), since
technically, one is not attempting to run the system during this
period. Many systems, such as the BRIJ machines, are operated for
167 hours per week. The operating ratio for these would use 167
as the denominator and the number of useful output hours as the
numerator, yielding a much smaller (but perhaps truer) ratio than  





 
                           TABLE XV

                  CHRONOLOGICAL ORDER OF 
       CUSTOMER ACCEPTAMCE OF VARIOUS CONPUTING SYSTEMS 

	1946		ENIAC
	1950	MAY	SEAC
	1950		WHIRLWIND-I
	1951	MAR	UNIVAC
	1952		IAS
	1952	MAR	ORDVAC
	1952	MAR	MANIAC
	1952	JUN	TELEREGISTER- SPEDDH
	1952	JUL	MAGNETRONIC RESERVISOR
	1952	SEP	ILLIAC
	1953	MAR	LOG
	1955	APR	OARAC
	1953	JUN	ORACLE
	1955	JUL	RAYDAC
	1953	AUG	MAGNEFILE-D
	1953	AUG	UNI-SCI (ERA-ll03A)
	1953	SEP	FLAC
	1953	OCT	UDEC-II
	1955	DEC	UDEC-I
	1953	DEC	MINIAC
	1954	FEB	MAGNEFILE-B
	1954	MAR	ELECOM-120A
	1954	MAR	JOHNNIAC
	1954	APR	DYSEAC
	1954	APR	ORDFIAC
	1954	JUN	ALWAC-XII
	1954	JUN	CIRCLE
	1954	JUL	FERRANTI MARK-I
	1954	JUL	MDP-MSI- 5014
	1954	AUG	BENDIX-D12
	1954	AUG	DATATRON
	1954	SEP	MODAC-4O4
	1954	DEC	TIM-II
	1955	FEB	IBM-702
	1955	FEB	NORC
	1955	MAR	WHITESAC
	1955		PENNBTAC



a system operated on an 8-hour 5-day week shift and using off-time
for servicing. This may yield operating ratios of the order of
.90 to 1.00 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 obtain-
ing output information, particularly where volatile storage media
are being used.

	Every large scale, electronic digital computer in the
United States is still in an operating condition. However, many
are probably approaching the age of retirement and replacement.
Constant improvement may have replaced many of the original
components of a system. The next few years will see the retire-
ment of many of the older systems; such retirement may take the
form of salvage of parts or use for educational and training
purposes.




MARTIN H. WEIK


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