Standard Oil Company (indiana)

John L Shanks

John W Supernaw

Randol R Read

Everett L Cox

An interface for coupling a computer to a plurality of magnetic tape transports, including dual-density transports and combinations of high and low density transports. The interface includes an automatic density selector for detecting the density of data stored on a tape prior to reading and for storing this information for as long as the tape is being used. A read-only memory and other logic circuitry translate computer operating commands into commands readable by a transport formatter. The interface also couples digital data between the computer and the formatter and converts formatter status information into language readable by the computer.

Computer to tape deck interface

This disclosure describes a decoding system for decoding and formatting digital data recorded on magnetic tape in the STR ('speed-tolerant recording') format. The digital words are stored in cells of about equal width except that the leading cell of each word, called a 'sync' cell, is of double width. Each cell starts with a positive pulse, and a cell detector provides a signal each time this occurs. The apparatus includes a data detector, which analyzes the width of this positive pulse relative to the cell width to determine whether the cell is a 1 bit or a 0 bit. Since the measurement is relative, cell length, i.e., total cell time, is not important. The bit determination is loaded into a shift register. Other apparatus determines the width of the cell, so that a sync cell detector can determine whether a sync cell is present or not. When a sync cell is detected, a pulse is generated which actuates the output buffer register to load the bits from the shift register. Data flows from buffer to a computer.

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Tulsa, OK, United States of America

John L Shanks