TM03 magtape controller

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The TM03 magtape formatter is a MASSBUS device controller, effectively an upgraded version of the TM02 magtape controller. It is used with 1/2" magnetic tape drives; supported drives include the TE16 (45 inches per second), TU45 (75 IPS) and TU77 (125 IPS). It can handle 800 bits/inch (NRZI) and 1600 bits/inch (PE - Phase Encoded).

A TM03 can control up to 8 drives, although the TM03 and drives count as only a single MASSBUS device. The TM03 controller connects to all the drives over a 'slave bus'; all the drives are identical (unlike in the TM11/TU10 system.


The TM03 is implemented as a set of boards, all of which plug into a custom hex-high nine-slot backplane, usually mounted in a special box in the first tape drive rack. The modules include three hex-size boards, six quad-size modules, and six dual-high modules.

The hex modules are:

  • M8933 - Tape Control Common Mode
  • M8909 - MASSBUS Interface (the documentation refers to both the M8909, and M8909-YA)
  • Bit Fiddler
    • M8906 for use with a PDP-11
    • M8915 for use with a PDP-10 and TE16 or TU45
    • M8915-YA for use with a PDP-10 and TU77

The quad modules are:

  • 3 x M8901 - Data Sync (PE)
    • M8901-YA for the TE16
    • M8901-YB for the TU45
    • M8901-YC for the TU77
  • M8932 - Tape Control (PE)
  • M8934 - Tape Control (NRZI)
    • M8934 for the TE16 and TU77
    • M8934-YA for the TU45
  • M8905-YB - Maintenance Register

The dual modules are:

  • M8937 - Control and Write Drivers
  • M8908-YA
  • M8908
  • 3 x M5903 or M5903-YA

The first three are the drive slave bus interface; the last three are the MASSBUS interface.

Drive bus

To be added.

External links