On 9/17/20 8:56 AM, Jon Elson via cctalk wrote: > This is not necessarily true. Many systems can handle "VBS" (Variable > Block Sequential) tape files. > But, yes, fixed block size is more common.
"Hybrid" files are quite common, where all blocks are the same size, but for the last one. Or, in the case of some PDP 11 tapes, there's a short record containing file name, etc. followed by the file data in uniformly-sized blocks, but for the last one in the file. Prior to uniform conventions, tape files were anything that the originator could dream up with regards to block sizes. Very often, the correspondence was 1 record = 1 block. Even the convention of 80 character ANSI tape labels ran afoul of some 36 bit systems, where label records were 81 bytes. --Chuck
