ENIAC World Wide Web
EDVAC Electronic Discrete Variable Automatic Computer (U.S. Army Photo)
Exterior ballistics problems such as high altitude, 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, was 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.
Internal number system Binary Binary digits per word 44 Binary digits per instruction 4 bits/command 10 bits each address Instruction per word 1 Instructions decoded 16 Instruction used 12 Arithmetic system Floating and Fixed point Instruction type Four-address code
EDVAC Floating Point (U.S. Army Photo)
-(1-2^-43) less than or equal to n less than or equal to (1-2^-43)
-(1-2^-33)2^511 less than or equal to n less than or equal to (1-2^-33)2^511
The fractional part of floating point number has 33 bits plus sign, and the exponent of 2 may range from -512 to +511.
Alpha-Add Beta-Add Gamma-Add Delta-Add Order 1-10 11-20 21-30 31-40 41-44
Microsec Add time (includ. stor. access) 864 (min 192 max 1,536) Mult time (includ. stor. access) 2,880 (min 2,208 max 3,552) Div time (includ. stor. access) 2,930 (min 2,256 max 3,600) Construction Vacuum-tubes and Diode-gates Number of rapid access word registers 4 Basic pulse repetition rate 1.0 megacycle/sec Arithmetic mode Serial Timing Synchronous Operation Sequential
Number of Number of Media Words Digits Access Microsec Mercury A.D.L. 1,024 48-384 48-384 Magnetic Drum 4,608 48/Word 17,000 Includes relay hunting and closure. The rate of information transfer to and from the drum is at one megacycle per second. The block length is optional from 1 to 384 words per transfer instruction. Magnetic tape 48/Word Maximum number of units that can be connected to the system 7 Units Maximum number of characters per linear inch of tape 112 Char/inch Channels or tracks on the tape 8 Track/tape Blank tape separating each record 1.5 Inches Tape speed 75 Inches/sec Start time 3 Milliseconds Stop time 3 Milliseconds Average time for experienced operator to change reel of tape 30 Seconds Physical properties of tape Width 5/8 Inches Length of reel 1,250/2,500 Feet Composition Red Oxide
The magnetic tape system has the following features: Variable block length from 2 to 1,024 words. The search order releases the machine for computation during search. Information which has been taken from a block and operated upon, can be automatically re-recorded in the same block.
Media Speed Photoelectric Tape Reader 942 sexadec char/sec 78 words/sec Card Reader (IBM) 146 cards/min 8 words/card
Media Speed Paper Tape Perf. 6 sexadec char/sec 30 words/min Teletypewriter 6 sexadec char/sec 30 words/min Card Punch 125 cards/min 1,000 words/min
Type Quantity Type Quantity Tubes, total 5,937 6Y6 1,000 6AN5 275 6J6 1,500 2D21 160 6AG7 1,127 6SN7 150 6V6 900 6AS6 50 6L6 275 Misc 500 Diodes, total 12,000 1N297 6,000 Misc 1,200 1N 34 4,800 Transistors, total 328 2N398 256 2N123 4 2N1008B 60 2N167 4 2N 43 4
Two arithmetic units perform computation simultaneously, discrepancies halt machine. Unused commands halt machine. Paper tape reader error detection.
Power, computer 52 K.W. Space, computer 490 sq. ft. floor Weight, computer 17,300 lbs. Power, air cond. 25 K.W. Space, air cond. 6 sq. ft. floor Weight, air cond. 4,345 lbs. Capacity, air cond 20 Tons
Number produced 1 Number in current operation 1
Approximate cost, basic system $467,000 Rental rates for additional equipment I.B.M. card reader $82.50 per month I.B.M. card punch $93.50 per month
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 time Approx. 8 hours Good time 145 hours/week Attempted to run time 168 hours/week Operating ratio 0.87
Figures based on last 3 years. The 23 hours per week are devoted to scheduled and unscheduled maintenance, testing, modifications and improvements, time lost due to error, etc. The 145 hours are good, useful production time. EDVAC has been operating since 1949.
Ballistic Research Laboratories Aberdeen Proving Ground, MD
A second magnetic drum system, of 16,128 words capacity is being added to the EDVAC. The transistorized track selector will permit channel switching in 48 microseconds. Synchronous Magnetic Drum (U.S. Army Photo)