Reversible multitrack magnetic tape storage system with multiframe error protection facility

A system for reversibly storing digital data on a magnetic tape record carrier having a plurality of parallel recording tracks, frame-based error protection being provided by encoding the data in accordance with a product code having first code words and second code words, the code symbols of each first code word being distributed over a single track and the code symbols of each second code word being cyclically distributed over all of said tracks;

• said system comprising:
• tape drive means having (i) a read mode in which it operates in a first servo loop which is closed and is controlled by a synchronizing signal derived from data read from the record carrier, and (ii) a write mode in which it operates in a second open loop wherein tape speed is maintained at a preset value;
• bidirectional buffer means for providing intermediate storage of data frames between said record carrier and an external data source or sink;
• an amble frame generator for supplying amble frames, said tape drive means being adapted when in the write mode to selectively convey either an amble frame from said generator or a data frame from said buffer means to said record carrier;
• and
• encoding means which, when said tape drive means is in the write mode, is actuated to provide frame-wise error protection by encoding in accordance with a Reed-Solomon code applied to a plurality of uniform series of symbols across a plurality of successive data frames without taking account of amble frames, the encoded symbols which are thereby produced being assigned to exclusive-redundancy frames.