"OPC-1" (OKI Parametron Computer-1), completed in March 1959, was developed in order to model an accounting processing system. It did not have software for controlling the whole system such as an OS or a monitor. It enabled programming using 24 machine instructions with the following two methods:
(1) Wired Program
This method was designed based on the wiring technique used for patch board of telephone exchange, which enabled to do easy programming in conjunction with equipment such as a paper card reader and a printer.
A patch board consists of 22 lines x 14 rows of sockets called hubs, and allows a program comprising up to 16 steps to be created. Hubs were classified into program-step hubs, program-suppression hubs, operation hubs, etc., and several hubs were connected by wires to create a machine instruction.
These operations enabled the computer to read numeric values from a paper tape or card, perform simple calculations and print out characters by a printer. If more complicated calculations were required, the stored program method described below would be used.
(2) Stored Program
With this method, a program was pre-stored on a magnetic drum, and the operator had the computer perform the corresponding instruction by pressing the "Restart" key. To store a program on the magnetic drum, the operator entered a specified code (1101) at the beginning of a paper tape, entered the program after the code, and then pressed the "Start" key to make the computer automatically store the program.
This method was notable at a time when the commonly used method was to manually instruct a computer to store a machine language called "Manual Order", and then have the computer read the machine language called a "bootstrap" on a paper tape.