【Fujitsu】 FACOM 601 Magnetic Tape Unit

The FACOM 601 was Fujitsu's first magnetic tape unit for computers employing a tension arm shock absorber mechanism. It was completed in August 1960.

The FACOM 601 employed a tape drive system where the tape was fed by pressing it against a continuously rotating capstan with a pinch roller. There were two capstans, one each for forward and reverse feed, which rotated in directions opposite each other. A tension arm shock absorber mechanism was used because the reel could not respond to sudden movements when starting or stopping the tape. Recording density of the unit was a low 133bpi (bits per inch), but Fujitsu later developed the FACOM 602 which increased this recording density to 333bpi, and also allowed reading of tapes written with the FACOM 601. With this tape drive system, it was impossible to prevent shock to the tape during starting and stopping, but reliability was ensured by using sandwich tape. However, recording resolution was poor, and it was extremely difficult to improve recording density.

Main Specifications of FACOM 601/602 Magnetic Tape Units
  FACOM 601L FACOM 602
Completion date August 1960 About 1962
Tape speed 75inch/s
Data transfer speed 10,000 digits/s 25,000/10,000 digits/s
Recording density(bpi) 133 333/133
Recording system NRZI
Head 7-track write/read 2-gap head
Tape used Sandwich type 3M tape #486
Tape drive system Capstan and pinch roller system
(Tension arm shock absorber mechanism)
Rewind time 6.5 min
2-channel cross call Not possible
Main connected systems FACOM 222, 231 FACOM 222, 231, 241

FACOM 601 Magnetic Tape UnitFACOM 601 connected to the FACOM 222FACOM 602 Magnetic Tape UnitFACOM 602 connected to the FACOM 241D