【Oki Electric Industry】 OKITAC-4500

The OKITAC-4500 was fully equipped with the online real-time capabilities and input/output control capabilities necessary for scientific and engineering calculation and measurement, and for process control. It was completed and marketed in 1970 as an enhanced version of the OKITAC-4300. The OKITAC-4500 design was unsatisfactory from the standpoint of performance. Price rose due to excessive focus on general applicability, and there were limitations on function which made the system inconvenient to use. Therefore, applications were limited to tasks such as scientific and engineering calculation, process control, instrument control and circuit control, and in these fields, the machine was developed as a computer having the same performance as a large computer. The memory unit could cope with a wide range of temperatures (-25°C-75°c); memory capacity was 8K words (1 word = 16 bits) -65K words; interrupts ranged from 8 to 24 levels; the OS was DOS (Disk Operating System); and assembler, FORTRAN and COBOL were used as the programming language.

Furthermore, the OKITAC-4500C, which achieved higher speed using TTL-ICs (integrated circuit elements), was announced in 1973, and that machine was active in facilities such as the research laboratories of universities and government organizations.

OKITAC-4500 Model Specifications
  OKITAC-4500 OKITAC-4500C
Announcement date April 1970 1973
CPU 8bit independently developed CPU
Memory element Magnetic core
Main memory capacity 8K-65Kword (1 word = 16 bits)
Cycle time 1.5µs 600ns
Instructions 1-word-1-instruction, 2-words-1-instruction
Address systems 11/2 system, page system, absolute address system, relative address system, indirect address system
Number of instructions 83 (Excluding input/output instructions)
Arithmetic speed
  Fixed point Floating point
3.0µs 35.5µs
Multiplication 13.5µs 39.1µs
Division 14.5µs 50.1µs
  Fixed point Floating point
1.4µs 3.78S
Multiplication 6.16µs 10.22µs
Division 7.0µs 10.78µs
Interrupt levels Basic 8 levels, 24 levels optiona Basic 16 levels, 24 levels optional
Real-time lock 3 (Optional)
Input/Output control
  • Selector channels: 2
  • Multiplexer channels: 1
  • External connection channels: 1 (Free)