ENIAC World Wide Web
ENIAC Electronic Numerical Integrator and Computer MANUFACTURER Moore School of Electrical Engineering University of Pennsylvania OPERATING AGENCY U.S. Army Ordnance Corps Ballistic Research Laboratories Aberdeen Proving Ground, MD
Timing Synchronous Operation Sequential
Internal Decimal in basic computer, binary coded decimal in magnetic storage.
Decimal digits per word 10 plus sign Decimal digits per instruction 2 Instructions per word 5 or 6 Total no. of instructions decoded 100 Total no. of instructions used 97 Arithmetic system Fixed-point Instruction type One-Address Code Number range 10^-10 -1 to 1-10^-10
Add time (excluding storage access) 200 microsec Multiply time ( " " " ) 2,800 microsec Divide time ( " " " ) 24,000 microsec Construction: Vacuum-tubes Number of rapid access word registers 120 Basic pulse repetition rate 60-125 kilocycles/sec variable. Arithmetic Mode: Parallel
Information is transferred in parallel as a serial train of pulses.
Microsec Media Words Access Vacuum-tubes 20 200 Magnetic core 100 200 Function table 304 lines of 12 dec digits + sign on each constant set-switch Plug board 96 lines of 12 dec digits + sign each (IBM) Relays 8 buffer capable of storing contents of one card
Media Speed IBM Cards 125 cards/min
Each card has 8 ten decimal digit words plus signs.
Media Speed IBM Cards 100 cards/min
200 millisec of card cycle are available for other computer operations. At 50 cards/min rate, 800 millisec are available for computer operations per card cycle.
Tubes 17,468 Tube types 16 Crystal diodes 7,200 Magnetic elements 4,100
Power consumption, Computer 174 K.W. Space occupied, Computer 1,800 sq ft Air conditioning Forced outside air.
Number produced 1 Number in current operation 1
Additional equipment Magnetic storage $29,706.50 Rental rates for additional equipment: I.B.M. card reader $82.50 per month I.B.M. card punch $77.50 per month Approximate cost of basic system $750,000
Daily operation No. of Tech. 3 - 8 hour shifts 6 7 days/week
A minimum requirement of operation and servicing on a 24-hour-day, 7-day- week basis. No engineers are assigned to operation of the machine, but they are used for design, development of improvements and consultation when total breakdowns occur.
Date unit passed acceptance test 1946 Average error free running period 5.6 hrs Operating ratio 0.69 Good time 113 hrs (Figures for 1955) Attempted to run 164 hrs/wk No. of different kinds of plug-in units 44 No. of separate cabinets (excluding power and air cond.) 42 Operating ratio figures for 1954: Operating ratio 0.70 Good time 116 hrs Attempted to run 166 hrs/wk
There are four modes of operation: Continuous, Pulse time, Add time, or Instruction time.
A manual pre-set stop box is available.
Count instructions and transfer instructions are used.