Abstract: A data input device for use in an electrically noisy environment incorporates a plurality of conductive strips, arranged in rows and columns, mounted on a transparent body in front of a display device. Electrical noise is induced constantly in the conductive strips. When an operator places his finger in close association with one or more of the rows and columns, the amplitude of the electrical noise on such strips changes markedly. The change in noise level is detected and used to provide an output identifying the row and/or column in the vicinity of the operator's finger.

Abstract: A control unit for supervising operation of data transmission to and from a data storage device such as a disk storage device, has a stored program for the unit, and a random access memory sufficient to store an entire block of data received from the data storage device. In one arrangement, the control unit works in conjunction with external data processing apparatus, and the control unit controls interchange of data between the data processing apparatus and the data storage device. The external data processing apparatus has a reduced memory capacity requirement, because of the control unit, and delays caused by static timing requirements are minimized. When the data storage device is a disk storage device, reading is performed without delay, using the first available sector of the disk in a given track.