The HITAC 3030 was computer system designed specifically for real-time information processing and to serve as the central processing unit for the MARS-101 seat reservation system operated by the Japanese National Railways (today JR). The computer’s core memory had a capacity of 4,096 words (with a cycling time of 10 microseconds; each word was 40 bits long) and each word had two instructions using a paired-order architecture. Addition and subtraction operations could be completed in about 18 microseconds, which was an extremely fast calculation speed for the time. Although calculations were done in binary to meet the real-time processing requirement, the HITAC 3030 had some rather unique innovations, such as binary-coded decimal additions and subtractions, processing of parts of a single word using a filter register, and a calculation function that repeated either one or two instructions. Other special characteristics included a sophisticated interrupt function, a function that enabled time-shared use of the magnetic core memory by means of five separate data channels, and an I/O controller with five separate I/O channels. These functions drastically improved the computer’s simultaneous use of I/O devices.
The HITAC 3030 was delivered to the Japanese National Railways in 1963 and was connected to 83 terminals located across the country. Reservation services began the following year. The HITAC 3030 was used in other online systems, such as ANA’s seat reservation system and Tokai Bank’s currency exchange system (which had a core memory capacity of 8,196 words).