Methods for recording and reading data from a record member having data in any one of a plurality of block formats including determining length of records being transferred

In a machine-effected method of transferring data signals arranged in data records of said data signals, between a peripheral controller and a data storage member, each data record having a number of bytes of data, said number may vary from data record to data record, wherein the data records are recorded on the storage member in signal blocks, said signal blocks being separated by inter-block gaps in which no data signals are recorded and wherein each of the signal blocks recorded on said storage member may contain one or more of said data records;

• wherein said storage member contains recording format demarcation machine sensible indications, first ones of said format indications signifying an ensuing format on said storage member as indicating signal blocks recorded in either first or second formats while second ones of said format indications signifying the ensuing format is undetermined, said first format having said signal blocks storing one of said records and said second format having said signal blocks storing said predetermined number of data records;
• including machine-executed steps of:
• determining the number of said data bytes in one of the data records;
• determining that said data records are in one file of said data records wherein each of said data records in said one file having an identical number of data bytes;
• and
• inserting a predetermined number of said data records into one of said signal blocks including the step of dividing said one signal block into extends and inserting identifications of said data records in each of said extends for respectively identifying the data records in said one signal block;
• while reading signal blocks recorded on said storage member, sensing one of said format indications, then in response to sensing said first one of said format indications indicating that the number of records in the next ensuing signal block to be sensed is recorded in the indicated first or second format, respectively;
• sensing said ensuing signal blocks for retrieving one of said data records from each signal block recorded in said first format and said predetermined number of said data records from each signal block recorded in said second format;
• and
• sensing a second one of said format indications, then reading a next signal block, examining said read next signal block for ascertaining whether said next read signal block was recorded in said first or second formats, then reading a next ensuing signal block in said ascertained first or second format.