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 several weeks. These tertiary storage tapes will be created in duplicate each week and will be called history tapes. History tapes will automatically be erased after six months. No direct notice of file displacement will be made to each user; rather each user, upon examining his file directory, can by inspection see which files are still on the disk. Any attempt to use a displaced file will result in a console message to the user.

The above history tape procedure represents a compromise between automatic information disposal and the convenience of the user. The procedure which is illustrated in Figure 3.2 is done in conjunction with the normal disk editing procedures of dumping and loading the disk (at least daily).

Figure 3.2 Diagram of Disk Editing Procedure

The first phase of the procedure starts with the 7090 dump editor and 7090 dump control cards being recorded on magnetic tape via the 1401 to run as a standard 7090 FMS job. The job first processes control card files left on the disk by the time-sharing supervisor, and then 28