Hitachi HIPAC MK-1

This was Hitachi's first digital computer, developed to calculate the sag and tension of power transmission lines. It was completed in 1957. The transistors of the time were the point-contact type, with large variation in characteristics, low production volume and a high price. Parametrons, in contrast, were determined to be inexpensive and highly reliable, so it was decided to use them as the logic element. A magnetic drum was used as the memory unit because it was thought to have the best future prospects at the time.