Museum News
Visitor Feedback
Museum Trifolds
Print Your Own!
IBM History

Hardware Detail

Item Reference:
Machine Type:
Serial Number:
  Tape unit from 705
  The IBM 727 Magnetic Tape Unit was initially announced on September 25, 1953 for attachment to the IBM 701 and IBM 702, and later the 705. It became the standard tape drive for IBM's early vacuum tube era computer systems. The 727 was withdrawn from marketing on May 12, 1971.

The tape had seven parallel tracks, six for data and one to maintain parity. Tapes with character data (BCD) were recorded in even parity. Binary tapes used odd parity. Aluminum strips were glued several feet from the ends of the tape to serve as logical beginning and end of tape markers. Write protection was provided by a removable plastic ring in the back of the tape reel.

Tape speed was 75 inches / second with a transfer rate of 15,000 characters / second. Character density was 200 characters / inch. The tape was fed from each reel through a vacuum column, allowing fast acceleration of the tape through the heads without having to wait for the inertia involved in starting and stopping the rotation of the reels themselves.
Date of Origin:


Click to view a larger image

On Display - HLG19 Commissioned By: Museum Until: