Abstract: A helical type tape recording and reproducing system records blocks of user data of predetermined size by reformatting the user data blocks into physical blocks that are recorded on tape, with the physical blocks being recorded as double frames. Each double frame is recorded on a set of successive helical tracks, preferably 32 tracks. Each double frame has system format data interleaved with the user data block data which identifies the double frame as being of a particular type. The present invention is directed to the types of double frames that are used to begin a recording, particularly an append recording which involves recording by the system at a previously recorded tape which may have been recorded by a different system, as well as the types of double frame that are used to end a recording.

Abstract: A tape data recording and reproducing system is disclosed which has an over-writing capability which can result in previously recorded data continuing to exist on the tape after the over-writing has been completed. The present invention uses cyclical redundancy check data that is normally recorded with the data to determine if the data recovered during reproducing is valid data.