Abstract: Apparatus for transferring data and other information between a data processing unit and a rectangular memory card which includes an optically readable data memory unit having a succession of substantially concentric data storage tracks thereon, the card also including at least one microelectronic component which stores further information. Such component is connected to connection points on the surface of the card. Data is read from the tracks of the memory unit by optical scanning during rotation of the card about the axis of symmetry of the memory unit, and information is transferred between the microelectronic component and the data processing unit by an information transfer unit which is coupled to the connection points on the card and to the data processing unit.

Abstract: A dropout correction circuit is described. It comprises a dropout detector which compares a signal with a reference level and controls a switch which connects an output of the circuit to a line memory, in order to insert a corresponding part of a preceding line during such a dropout. In order to enable the reference level to be selected as high as possible the color carrier is extracted before the video signal is applied to the dropout detector.

Abstract: A system for transmitting digital information including a coding arrangement, a transfer medium, for example a record carrier, and a decoding arrangement.In the coding arrangement the digital information is received as groups of input words which are encoded to form code words, each code word corresponding to an input word. Each code word has a time duration equal to s.tau..sub.O and each is assembled from M subgroups G.sub.m of I signal positions t.sub.mi spaced by equal time intervals .tau., where m is a number from 1 to M, inclusive, corresponding to a subgroup G.sub.m and i is a number within each subgroup G.sub.m from 1 to I inclusive. In each subgroup G.sub.m, k of these signal positions t.sub.mi are always occupied by a signal which is distinguishable from the signal in unoccupied positions, where k is an integer smaller than I (1.ltoreq.k.ltoreq.I-1). The first positions of the subgroups G.sub.m are located at mutually different time intervals .epsilon..sub.