Note on Some Problems in Geophysical Data Acquisition on Magnetic Tape

Gapped tapes, which are required by most computers, are often difficult or expensive to produce on-line. As a substitute, a reference word or byte may be introduced periodically, or a special track may be devoted to indicating the, beginning of every ith word. A better solution is to use special hardware enabling the machine to search for the reference word. The system in use on the Rice computer is a variation of the special track method. It enables one to start and stop reading anywhere and to minimize the loss of data by reading both forward and backward. Real time needs to be periodically recorded, for example, in place of a normal data word.