Quarter-Inch Tape Format
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19
Since high level programming is expensive to change, it is beneficial to be able to make different models of tape drives transparent to high- level software. This disclosure describes a way of making two different models of tape drives software transparent. Standard tape data blocks can vary in length between 18 and 32K-1 bytes. This is no problem for variable-length drives as they handle data blocks at the given length. Fixed-block drives can only handle data blocks at a maximum fixed length of, given in this case, 512 bytes. The first data block contains a two-byte data length. Since no data block length is greater than 32K-1 bytes, the two bytes suffice to specify the desired length. This information tells how many 512-byte data blocks are written subsequently.