The following may help readers who save data on tape. It is especially useful when data must be constantly updated.

Use one tape for each set of data. This is used to hold two versions of the data; the most recent copy and the second most recent copy. One set of data is recorded on each side of the tape, to ensure a recent version of the data is available despite accidents.

Each time the tape is used, load the most recent data and save over the second most recent version. When data is saved, rewind the tape to the beginning of the newest data. This saves time when loading and shows which is the most recent side.

R. J. Walton
Littlemore, Oxford