1.0  Input a binary block
             _____ _ ______ _____



                                   *********
                                   * fgetb *
                                   *********


        Usage

                fgetb(buffer, maxbytes, lbn, iop);
                char            *buffer;
                int             bufsiz;
                unsigned        lbn;
                FILE            *iop;

        Description

                Read one or more disk blocks from  the  indicated  file.
                Bufsiz is the buffer size and must be a multiple of 512.
                Lbn is the logical block number to read.

                The block is read by a direct  QIO  IO.RVB  call.   Your
                program  should  only  use  block reads or writes unless
                your very sure of the effect of mixing io types.

                If sucessfull,  the  actual  number  of  bytes  read  is
                returned.   On  error,  the  dsw  or  iosb error code is
                returned.

                Fgetb() is not present on Unix standard I/O libraries.

        Bugs

                Only works with RSX.  Lbn should be a long, but  if  you
                need  to read more than 65K blocks into a file, you know
                how to fix this routine.