3/15/72 PPT (IV)





3/15/72                                                  PPT (IV)





NAME            ppt  --  punched paper tape



SYNOPSIS        --



DESCRIPTION     ppt refers to the paper tape reader or punch, de-

                pending on whether it is read or written.



                When ppt is opened for writing, a 100-character

                leader is punched.  Thereafter each byte written

                is punched on the tape.  No editing of the char-

                acters is performed.  When the file is closed, a

                100-character trailer is punched.



                When ppt is opened for reading, the process waits

                until tape is placed in the reader and the reader

                is on-line.  Then requests to read cause the

                characters read to be passed back to the program,

                again without any editing.  This means that sev-

                eral null characters will usually appear at the

                beginning of the file.  Likewise several nulls

                are likely to appear at the end.  End-of-file is

                generated when the tape runs out.



                Seek calls for this file are meaningless and are

                effectively ignored (however, the read/write

                pointers are maintained and an arbitrary sequence

                of reads or writes intermixed with seeks will

                give apparently correct results when checked with

                tell).



FILES           found in /dev



SEE ALSO        --



DIAGNOSTICS     --



BUGS            --



OWNER           ken, dmr
squoze.net
