【NEC】 NEAC-1101

In March 1958, NEC finished its first digital computer, the NEAC-1101. This machine used parametrons, invented by Eiichi Goto in 1954, and was perfected by using a single-turn transformer coupling system independently devised by NEC. This computer was designed for scientific and engineering calculations, and was Japan's first computer to use floating point operations. It was capable of decimal 7-digit floating point operations. It used 3,600 parametrons, 29 types of instructions, and had average performance of 3.5ms for addition/subtraction and 8.0ms for multiplication/division. The memory employed ferrite cores (magnetic core matrix system using the 2 ACs with different frequency), and memory capacity was 256 words (32-digit configuration). The NEAC-1101 was enhanced via improvements like expanding the memory capacity to 512 words, and was used for about 8 years for scientific and engineering calculations at NEC's research laboratory. The results from developing this computer contributed greatly to the development of subsequent parametron computers at NEC.

Specifications of NEAC-1101
Completion date
March 1958
Control system Stored program system
External numeric words
Decimal 7-digit, Characteristic ±8
Internal numeric words Binary
 (Long word) 32 digits (bits)
 Mantissa: 25 digits + sign
 Characteristic: 5 digits
 (Short word) 16 digits
Commands (Instructions) 1 address system, 29 types
Arithmetic system Parallel, floating point
Operation speed Addition/Subtraction: Average 3.5ms
Multiplication/Division: Average 8.0ms
Arithmetic element Parametron (3,600 elements)
 Drive frequency: 2MHz
 off-and-on frequency: 19.5kHz
Memory element Ferrite core
 Outer diameter 2mm, inner diameter 1mm, thickness 0.6mm
 Magnetic core matrix system using 2 ACs with different  frequency
 Capacity: 256 words
Input/Output devices Paper tape reader 600 char/min
Paper tape punch 600 char/min
Typewriter 400char/min