A process and apparatus for transferring information between an information store and a data channel. During the recording process, the quantity of information to be recorded and, in the reading process, the capacity of an apparatus associated with the data channel to be fed with the information read, is determined and, based upon the quantity of information determined in each case, the control magnitude is produced to drive the information store at a predetermined speed. Circuitry is provided for controlling the amplitude and phase of the information read from the information store to compensate for any variations in the speed of the information store.

The tape in a tape reader is braked to a stop relatively slowly instead of being stopped on one character. Two sprocket reading photocells are mounted on the tape reader to provide quadrature sprocket waveforms which are applied to a bi-directional sprocket counter coupled to the address conductors of a buffer memory. The data read off the tape by the tape reader is written into the buffer memory at the addresses indicated by the sprocket counter. An output pointer counter is also coupled to the buffer memory address conductors in parallel with the sprocket counter through a time division multiplexer. During the time interval in which the output pointer counter is connected to the buffer memory address conductors, data can be read out of the buffer memory at the address indicated by the output pointer counter independently of the sprocket counter.

For both recording and replay, a digital audio tape (14) is accelerated very rapidly by a motor servo (9), motor (8) and capstan (7) so that the tape speed overshoots nominal speed range before settling back to this range in an oscillatory manner. The digital samples are recorded and replayed via a head (15), a random access memory (16) and input/output electronics (19). During recording, the store (17) is precharged by starting to write in as soon as acceleration is initiated. Read-out to the tape is initiated as soon as the tape first reaches the nominal speed range. Uniformity of samples as recorded on the tape is preserved by clocking a read address generator (21) at a rate proportional to tape speed, signaled by a tachometer (7). The write address generator is clocked at the constant sampling rate. For replay the write address generator is clocked at the tape speed rate while the read address generator (21) is clocked at the constant sample rate. Write in and read out are both initiated when the tape speed first reaches the nominal range. The addresses provided by the generators (20 and 21) are compared by a comparator (22) which provides a reference signal to the servo (9) in an arrangement such as to adjust the tape speed always in the sense to maintain a constant degree of filling of the store (17).