Mitsui Bank started using Japan’s first online banking system in May 1965 for teller operations for ordinary deposits. The transaction was taken from a deposit slip and input at a branch teller terminal, which sent the transaction to a central computer unit. The central computer unit processed the transaction and updated the account’s ledger, which was stored on a disk drive, in real time. Operations at 10 Mitsui Bank branches in Tokyo went online during 1965. By 1968, all Tokyo branches and Osaka branches were connected to the system.
The system was constructed based on equipment and development experience from the Tokyo Olympic System that IBM Japan had operated in 1964. The central computer unit featured a duplex architecture, each section with one IBM 1410 (with a main memory of 60,000 characters) and one IBM 1440 (with a main memory of 16,000 characters). The storage unit consisted of two IBM 1301 large-capacity disk drives (each with a storage capacity of 55.80 million characters) and six removable IBM 1311 magnetic disk packs (each with a storage capacity of two million characters).
Note: One character = 16 bits