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ORDVAC Ordnance Variable Automatic Computer (U.S. Army Photo)
Exterior ballistics problems such as high altitudes, solar and lunar trajectories, computation for the preparation of firing tables and guidance control data for Ordnance weapons, including free flight and guided missiles.
Interior ballistic problems, including projectile, propellant, and launcher behavior, e.g., physical characteristics of solid propellants, equilibrium composition and thermodynamic properties of rocket propellants, computation of detonation waves for reflected shock waves, vibration of gun barrels and the flow of fluids in porous media.
Terminal ballistic problems, including nuclear, fragmentation and penetration effects in such areas as explosion kinetics, shaped charge behavior, ignition, and heat transfer.
Ballistic measurement problems, including photogrammetric, ionospheric, and damping of satellite spin calculations, reduction of satellite doppler tracking data, and computation of satellite orbital elements.
Weapon systems evaluation problems, including anti-aircraft and anti- missile evaluation, war game problems, linear programming for solution of Army logistical problems, probabilities of mine detonations, and lethal area and kill probabilities of mine detonations, and lethal area and kill probability studies of missiles.
Transistorized Arithmetic Unit (U.S. Army Photo)
Internal number system Binary
Binary digits per word 40
Instructions per word 2
Instruction type One Address
Binary digits in operation code 6 or 9
Binary digits in address 12 or 10
Instructions used 55 or 72
Arithmetic system Fixed point
Number range -1 less than x less than 1
Instruction word format
Left Instruction Right Instruction
6 2 12 6 2 12
Order Unused* Address Order Unused* Address
20 Bits 20 Bits
*One bit will be used to differentiate floating point numbers from fix point numbers
Rapid Access word registers - 3
Sexadecimal representation is used externally.
Negative numbers are handled as 2 complements.
Floating point operation may be programmed.
Dual code - ORDVAC operates on a dual code basis. The codes are, on a two
instructions per word basis, i.e., 20 digits per instruction:
Code A - 1,024 words of storage:
9 digit, command
1 digit, spare
10 digit, address
Code B - 4,096 words of storage:
6 digit, command
2 digit, spare
12 digit, address
This system permits utilization of routines developed previous to the 4,096-
word operation change over.
Magnetic core memory (U.S. Army Photo)
Arithmetic mode Parallel Basic pulse rate Not pulse controlled Add time (basic addition by arithmetic unit) 14 microsec Multiply time (exclud. stor. access) 700 microsec Divide time (exclud. stor. access) 700 microsec
The total add time, including transfer to final register, is 50 microseconds. None of the above figures include access to storage.
Construction, Arithmetic unit only - Transistorized on printed circuit plug-in boards, using 1,000 Type 2N128 transistors.
Timing Asynchronous Operation ParallelTransistorized Channel Selector (U.S. Army Photo)
Media Words Digits Access
Magnetic core 4,096 163,840 bits 15 microsec
Magnetic drum 10,032 401,280 bits 80,000 microsec
/48 words
Magnetic drum purchased from ERA Division of Sperry Rand, Incorporated. The Track selector for the magnetic drum has been transistorized. Magnetic core storage unit purchased from Telemeter Magnetics, Incorporated. Both above storage units adapted to ORDVAC and installed by Ballistic Research Laboratories personnel.
Media Speed
Teletype tape (5 hole) 2.5 words per sec
Punched cards 40 words per sec (bin)
8 words per sec (dec)
Ferranti Hi-speed Paper
Tape Reader 20 words per sec (bin)
Magnetic tape 300 words per sec
The special purpose one inch wide magnetic tape system for transferring telemetered data to ORDVAC has 6 information tracks and 3 control tracks.
Media Speed
Teletype page printer 0.4 words per sec
Teletype tape 0.4 words per sec
Punched cards 40 words per sec (bin)
8 words per sec (dec)
Transistorized magnetic core contents display.
Tubes
Type Quan Type Quan
5964 817 C6J 28
5687 420 6X5 4
2C51 568 0C3 4
5965 637 6SF5 4
6AL5 47 6AC7 4
6A67 2 12SN7 12
2D21 160 12AU7 1
6080 21 6AH6 9
6AN5 13 6350 86
0B2 14 6829 2
7AK7 16 6216 2
5963 46 6BJ7 42
6AV6 13 6197 90
5R4 2 6293 193
6L6 26 5998 72
12AX7 22 6336 27
6X4 6 350B 4
5651 12 0A2 3
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6AQ5 1 Total 3,430
Transistors
Type Quan Type Quan
2N162 20 2N1056 250
2N140 65 2N113 75
2N128 1,300 2N426 25
2N109 346 2N425 10
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Total 2,091
Diodes
Type Quan Type Quan
1N91 418 1N63 15
1N93 162 1N58A 10
1N52 10 1N298 300
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Total 915
Power Consumption
Computer 40 K.W.
Core Memory 15 K.W.
Magnetic Drum 6 K.W.
Air Conditioning
Computer 15 Tons
Core Memory 7.5 Tons
Magnetic Drum 3 Tons
Space
Computer 630 cu ft 80 sp ft
Weight
Computer 3,000 lbs
Number produced to date 1 Number in current operation 1
Rental rates for additional equipment $648.57 per month The additional rented equipment is: I.B.M. punch $ 83.32 per month I.B.M. reader $ 82.50 I.B.M. reproducer $122.50 I.B.M. tabulator $360.25 Approximate cost of basic system $600,000.
Typical Personnel
Three 8-Hour Shifts
Supervisors 6
Analysts 3
Programmers and Coders 14
Clerks 1
Engineers 1
Technicians 6
No engineers are assigned to the operation of the machine, but are used for development and design of additions to the machine. The technicians consult the engineers when a total break-down occurs.
Average error-free running period Approx. 6 hours Good-time 7,475 hours Attempted to run time 8,760 hours/year Operating ratio 0.85
The above figures are based on the yearly average of the last 5 years. Approximately 2 hours per week are used for scheduled preventive maintenance and 10 hours per week are used for running computer test programs. The 1,286 hours difference above were used for testing, servicing, bad operating time, general improvement, and the incorporation of new components.
The ORDVAC belongs to the group of computers whose basic logic was developed by the Institute for Advanced Study and utilized in the IAS computer. This IAS family of computers is made up of such machines as the ILLIAC, ORACLE, AVIDAC, MANIAC, JOHNNIAC, MISTIC, and CYCLONE.
The ORDVAC is a direct-coupled machine using three-dimensional construction. A direct-coupled machine is one that connects the voltage level of one component directly to the input of the next, without voltage isolation between. This feature is very helpful in trouble-shooting the system. Three- dimensional construction is sometimes called low-capacitance wiring. In the ORDVAC, three-dimensional wiring is employed by placing the arithmetic unit and other controls on opposite sides, and interconnected wiring running across the open space between. The machine can be remotely controlled from commercial Teletype units.
ORDVAC is equipped with the option of two different instruction codes. Code -9 (nine bits per instruction) makes 1,024 words of high speed core storage available to the operator while Code -6 (six bits per instruction) makes 4,096 words of high speed storage available. Each code shares a common nine-bit decoder; however, when the code -6 option is used the instruction first passes through a code translator which translates the six bit instruction into its 9-bit equivalent. There is no loss of time while making the code translation.
The translator uses the following number of circuit elements.
Transistors
SB 100 135
2N 43 24
2N 140 12
----
Total 171
Crystal diodes 253
Resistors 305
Capacitors 23
The above components are mounted on 21 printed circuit boards. Power dissipation is approximately 5 watts.
Ballistic Research Laboratories
Aberdeen Proving Ground, MD
The Floating Point unit for the ORDVAC will be fully transistorized, with a number range of 2^127 to 2^-128, using a seven bit biased exponent. Numbers will be normalized automatically on transfer to storage. The mantissa of the normalized floating-point number will have a range of 1/2 greater than c greater than -1/2. This system will require that an existing register be converted from a one-sided shifting register to a two-sided shifting register.
Fully transistorized control circuitry for new indexing orders will be added in the near future.
General purpose magnetic tape stations will be added to the ORDVAC shortly, with provisions for 8 stations. ORDVAC will control read, write, re- wind forward and backward, move tape forward and back N words, starting at A address of memory, transfer to B address of memory for next instruction, re- record N words, playback N words, check for parity error, transfer on error, and other functions.
Magnetic Cores Quan OD ID Thick 172,032 100 70 30 mils 5,376 375 260 125 mils