rawtap manipulates .tap magtape container files used by SIMH. rawtap is
invoked by:

        rawtap -cae container [-r len] [...]

To create a new container file and append file(s):

        rawtap -c container [-r len] file ...

To append file(s) to an existing container file:

        rawtap -a container [-r len] file ...

To extract files from container file(s):

        rawtap -e container ...

Switches:

    -r len     Specify max tape record size when writing to tape.
               (1 <= len <= 65536). The new record size applies to all
               following files on the command line. There may be multiple
               "-r len" on the command line if the record size needs to be
               different across multiple files.