INT 14h,  18h    Read block (transfer from FOSSIL to user buffer)

      Entry:  CX         Maximum number of characters to transfer

              DX         Port number

              ES         Segment of user buffer

              DI         Offset into ES of user buffer

      Exit:   AX         Number of characters actually transferred

    A "no-wait"  block read of 0 to FFFFh characters from the FOSSIL inbound
    ring buffer to the calling routine's buffer. ES:DI are left unchanged by
    the call; the count of bytes actually transferred will be returned in AX.