Video replay store for a multi-channel digital video tape recorder

Claim 1

A video replay store for a multi-channel digital video tape recorder, the video replay store, comprising: a respective channel store for each channel, each said channel store comprising a plurality of field stores which are written in and read from cyclically; a respective field boundary detector for each channel, each said field boundary detector supplying a first pulse in response to each field boundary where an odd field changes to an even field, and a second pulse in response to each field boundary where an even field changes to an odd field, in the off-tape data in the respective channel; a replay store controller for supplying write requests and read requests in a predetermined sequence to all of said channel stores, said replay store controller stepping on from one state to a next state in said predetermined sequence in response to stepping pulses formed by each first said first pulse following a said second pulse and each first said second pulse following a said first pulse; and a control circuit for each said respective channel store, each said control circuit including a first gate circuit for gating each write request received from said replay store controller with a read request received from said replay store controller so as to derive a first output signal used to form a write enable, and a second gate circuit for gating each read request received from said replay store controller with said first output signal to derive a second output signal used to form a read enable, whereby said control circuit supplies write enables and read enables to said field stores with read enables dominating over write enables in the event of contention between a read enable and a write enable.