This was the first office computer equipped with a magnetic ledger in Japan. It was developed by Mitsubishi Electric based on the MELCOM83, and announced in 1970. Basic specifications were the same as the MELCOM83.
The magnetic ledger could record 520 digits of data (the memory system was semi-variable length with 6-12 digits per word) on magnetic stripes printed on the back of a cutform, and the system enabled speedy processing of ledger tasks, including not only balancing and totaling, but also insertion, expulsion and entry line alignment. Ledger feed speed was 254 mm/second. The system had 4 control keys (insert, expel, space up, space down) and a final line detector, and performed horizontal and vertical parity checking.
The MELCOM84 was exported to Europe, and was widely used in England, Germany and France.