Deutsche Itt Industries Gmbh

Hans-Jurgen Desor

Soenke Mehrgardt

Martin Winterer

A bus arbitration method for a multimaster system comprising a plurality of masters sharing a global data bus and a plurality of bus arbiters sharing a global identification bus. Each active bus arbiter applies to the identification bus a bus request signal containing a k-bit-wide identification word representative of the priority of the master associated with the bus arbiter. In each prioritization step of the bus grant cycle, a logic level is produced on the identification bus by logically combining bits of equal significance. This logic level is then compared with the corresponding bits of the applied identification words. The k bits of the identification words of the bus arbiters are placed on the identification bus on a time-graded basis; in each prioritization step of the bus grant cycle, only those bits of the identification words are placed on the identification bus which are of equal significance, and in each prioritization step of the bus grant cycle, those bus arbiters whose identification word bit in the prioritization step does not match the logic level of the identification bus are eliminated from the bus arbitration of the bus gram cycle.

Apparatus and methods for bus arbitration in a multimaster system

An improved digital video signal processing circuit, for common use in the recording and playback modes of a video tape recorder, has a chrominance processing circuit for processing the chrominance signal of the input digital composite video signal through a first baseband mixer, a chrominance processor, and a second baseband mixer, and a luminance processing circuit for frequency modulating/demodulating the luminance signal, so that the processed chrominance and luminance signals can be added together to form an output digital composite video signal. The improved digital circuit automatically regulates the frequencies of the mixing signals for both mixers using line stepping signals obtained from a horizontal line sweep generator in the luminance processing circuit. The possibility of phase errors is eliminated, and quadrature errors in the chrominance signal are prevented.

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Gundelfingen, Germany

Hans-Jurgen Desor