History (1978): DEC TU10 Magtape Drive

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TU10 magtape drive

The TU10 is a classic big magnetic tape drive from Digital Equipment Corporation, able to store 5-20MB on a 2,400-foot half-inch wide magnetic tape on a standard 10-half-inch reel.

It supports 7-track operation at 200, 556, and 800bpi, and 9-track at 800bpi.

The tape transport utilizes a single capstan, with vacuum columns. The TU10 drive contains a fair amount of electronics, in the form of FLIP CHIP modules in a 19-inch wide wire-wrap backplane (mounted fore and aft in the drive itself).

It was first used with the PDP-10 to connect to UNIBUS PDP-11’s, one of the TM11 series of magtape controllers is used. Details of the controller-Master interface are given there.

The TM11 controller connects to a ‘Master’ TU10 drive, which includes extra Flip Chip modules in its backplane; additional ‘Slave’ drives (up to seven) may be connected to the Master drive. The additional Flip Chips perform extra functions (e.g. CRC); they also convert the Positive bus from the controller to the Negative bus native to the TU10. The Master and Slave variants use the same wire-wrap backplane in the drive.

7-track/9-track differences
The only significant difference between the 7-track and 9-track drives is the head. The Flip Chip suite is the same for both, since the per-track boards are all 9-track, and simply leave the last two bits disconnected when used with a 7-track head.

The drive is be able to indicate (to the controller) whether it is a 7-track or 9-track.

In addition, certain operational delays are different; the M768 module contains configurable diode arrays to control these.

Drive bus
It is a negative logic bus used between drives, but not between positive bus controllers and the first drive; in such cases the first (Master) drive contains logic to convert from the positive bus used by the controller to the negative bus.

Tape speed: 45ips (Forward/Reverse), 150ips (Rewind)
Size: 19″Wx26″Dx26″H
Weight: 150lbs