    PC(IV)                       10/15/73                      PC(IV)

    NAME
         pc  -  PC-11 paper tape reader/punch

    DESCRIPTION
         Ppt  refers to the PC-11 paper tape reader or punch, depend-
         ing 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 characters 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 re-
         quests  to  read cause the characters read to be passed back
         to the program, again without any editing.  This means  that
         several  null  leader  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.

    FILES
         /dev/ppt

    BUGS
         If both the reader and the punch  are  open  simultaneously,
         the  trailer is sometimes not punched.  Sometimes the reader
         goes into a dead state in which it cannot be opened.

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