FACOM 603F Magnetic Tape Unit

FACOM 603 is a series of magnetic tape units, and was the first series in Japan employing a single capstan drive with a unique technology. The first model of the series is FACOM 603A completed in 1964.

In those days, the usefulness of computer systems greatly depended on the performance and reliability of magnetic tape units which were the most major external memory devices. An older tape transport drive than that of the FACOM 603 series had two capstans, and the two capstans were rotating mutually in opposite directions. To control the tape sending direction the magnetic tape was pressed against the appropriate capstan by a pinch roller. This control mechanism caused two big problems. One was that dust easily adhered to the recording surface of the magnetic tape because the pinch roller had to touch on the recording surface of the tape. Another problem was that the tape got strong shock when to change the tape sending direction.

A single capstan drive to transport a magnetic tape could avoid such problems mentioned above, but for practical use of it some new technique was required in order to quickly change the rotating direction of the capstan without strong shock against the tape. The single capstan drives employed for the FAQCOM 603 series solved the requirement through a new capstan servomotor system which enable to quickly and smoothly start/stop, through a vacuum column shock absorber system between a capstan and a reel of a tape and through additional ideas.

The simplicity of the single capstan drive of the FACOM 603 series brought high reliability, high performance and high maintainability. And consequently the series contributed to the spread of computer use in Japan.