Abstract: A time-division data multiplexing apparatus has first through Nth memories for temporarily storing first through Nth data blocks, and first through Nth address control circuits for controlling the first through Nth memories, respectively. Any nth address control circuit (n=1,2, . . . , N) calculates a time period A.sub.n of an nth time slot to be assigned to an nth data block from a data size M.sub.n of the nth data block stored in an nth memory and an available time period, T.sub.n indicated by an available time signal as a time period available for transmission of the nth through Nth data blocks, and controls the nth memory so as to read out data of the nth data block stored in the nth memory for A.sub.n while outputting for A.sub.n an selection signal S.sub.n indicating that the data stored in the nth memory is being read out.

Abstract: An apparatus for the protection of signal copy for preventing unauthorized copying of music software such as records, compact discs and music tape by recording is arranged such that when recording audio signals on a medium, certain supplemental information is added to the audio signal to be recorded, and in the process of copying by reproducing this medium, when the supplemental signal is detected in the reproduced signal, the copying action is stopped to protect it from being copied.

Abstract: An apparatus for the protection of signal copy for prevention unauthorized copying of music software such as records, compact discs and music tape by recording is arranged such that when recording audio signals on a medium, certain supplemental information is added to the audio signal to be recorded, and in the process of copying by reproducing this medium, when the supplemental signal is detected in the reproduced signal, the copying action is stopped to protect it from being copied.

Abstract: A digital signal processor for recording an analog signal in the form of a PCM signal and/or for reproducing the PCM signal in the form of an analog signal. It has functions of generating a first and a second check code each by performing a modulo 2 operation and of adding a third check code to each of the first and the second check codes for detecting errors. The original signals can thereby be restored completely, even when up to two data sets have been subjected to errors.

Abstract: A PCM recording processor which is synchronously operatable is disclosed. Two kinds of clock signals and two kinds of synchronizing signals enable two PCM recording processors to operate so as to be synchronized with each other. One master mode processor sends signals to plural slave mode processors through bi-directional input/output ports. These two modes are easily switchable. The synchronizing signals are generated by AND-gating each output of asynchronously cascaded counters in the timing generators in a PCM recording processor. A counter in the first stage of the cascaded counters is synchronously reset by the synchronizing signal and the other counters in the following stages are asynchronously reset by a delayed synchronizing signal in the slave mode processor.

Abstract: A digital audio signal recorder for obtaining coded signals having a first check code generator for generating the sum of module 2 for each bit of pieces of predetermined sampled data; and further has a circuit operatively coupled to said generator for arranging the sampled data, a first check code and a second check code at positions spaced on a time axis from each other. This invention also provides a method of generating such a digital audio signal. This invention is advantageous because it makes possible a low rate of redundancy and a simple decode circuit.

Abstract: An apparatus for detecting the recording and reproducing state of a video tape recorder used in conjunction with a pulse code modulation adapter and including a signal processor for comparing for a predetermined period data from signals transmitted from the pulse code modulation adapter apparatus to the video tape recorder with data from the signals received from the pulse code modulation adapter apparatus from the video tape recorder and detecting whether the video tape recorder is in the recording or reproducing state in dependence upon the result of the data comparison.