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rfc:rfc120
                      NETWORK PL1 SUBPROGRAMS
                           April 21, 1971
                          Mark Krilanovich
                       Computer Research Lab
                      University of California
                     Santa Barbara, California
                                                              [Page 1]

RFC 120 NETWORK PL1 SUBPROGRAMS

                              PREFACE
 The subroutines described in this document have been implemented at UCSB
 and make the Network (via the NCP) accessible to PL1 programs executing
 in the 360/75.  They are callable from within any PL1 main program or
 subroutine compiled at UCSB.
 A  set  of  assembly-language  written  subprograms  is  provided  to
 facilitate  the use of the Network by PL1 programmers.  They serve as
 an interface between the user and the Network Control Program  (NCP),
 which supervises all Network operations at this site.
 A concept  fundamental  to  PL1  Network  operations  is  that  of  a
 completion code variable.  Associated with each socket that is not in
 the closed state is a  unique  variable,  called  a  completion  code
 variable.   This  variable  serves  two  purposes:  it identifies the
 local socket referenced, and upon  completion  of  the  operation  it
 contains  a  completion code to indicate the outcome of the operation
 to the programmer.  It may be used at any time for any purpose  other
 than  Network  operations.   Its  value at the beginning of a Network
 operation is immaterial;  rather, it is the variable itself  that  is
 important.   In  all  Network  operations, whenever a completion code
 variable is called  for,  the  only  acceptable  attributes  for  the
 variable are BINARY FIXED(31,0)ALIGNED.
 In general, the subprograms will initiate the  operation,  and  enter
 the WAIT state (consume no CPU time) until notified by the NCP of the
 completion of the operation.  For  such  operations,  the  programmer
 supplies  a  time  limit,  with  attributes BINARY FIXED(31,0), which
 specifies, in tenths of a second, the  maximum  length  of  time  the
 subprogram  is  to  wait for the operation to complete.  If this time
 limit is exceeded, a completion code  is  supplied  to  indicate  the
 error,  and  control  is  returned  to  the calling program, with the
 operation still pending.
 In those operations requiring a socket to be specified by its  socket
 identifier,   the  following  format  is  used.   The  identifier  is
 specified as a BINARY FIXED(31,0) array, singly dimensioned  with  at
 least  two  elements,  and  with a lower subscript bound of one.  The
 first element is taken to be the site number, and the second  element
 the  socket  number.   A  socket number may have any value, positive,
 negative, or zero.  Since negative numbers are represented internally
 in two's complement form, for the purposes of the gender of a socket,
 a socket number is even or odd  according  to  whether  its  absolute
 value is even or odd, respectively.
                                                              [Page 2]

RFC 120 NETWORK PL1 SUBPROGRAMS

 Following is a description  of  each  subprogram,  its  function  and
 calling sequence.

(1) OPEN

   By invoking this subprogram, the user requests that  the  specified
   local  socket be removed from the closed state and thus be prepared
   to  participate  in  data  transfer.   There  are  three   distinct
   operations  that can be performed by this subprogram, and these are
   described below:
   (A)  CONNECT
        By initiating this  operation,  the  user  requests  that  the
        specified local socket be logically connected to the specified
        foreign socket, and that data transfer between the two sockets
        be enabled.  The subprogram will wait until the foreign socket
        either  accepts  or  rejects  the  connection  attempt.   This
        operation  is  valid  only  when  the  socket is in the closed
        state.
        The calling sequence is as follows:
             CALL @OPEN(cmpcd, time,lclsck,fgnsck,ws);
        where
             'cmpcd' is the completion code variable to be associated
                  with the local socket.
             'time' is the length of time the subprogram is to wait
                  for the completion of the operation.
             'lclsck' is the socket identifier of the local socket.
             'fgnsck' is the socket identifier of the foreign socket.
             'ws' is a workspace which has the same attributes as a
                  socket identifier, and, if the operation if
                  successful, will become associated with the local
                  socket for the life of the connection.  In response
                  to certain future operations, information may be
                  returned to the programmer in this workspace.
        The  following  completion  codes  are   possible   for   this
        operation:
             0,  The operation was successful and the connection has
                 been established
             4,  The specified completion code variable is already
                 assigned to a socket;  the operation was suppressed
             8,  The specified local socket is not in the closed
                                                              [Page 3]

RFC 120 NETWORK PL1 SUBPROGRAMS

                 state;  the operation was suppressed
            12,  All communication paths to the specified foreign site
                 are in use;  the operation was suppressed
            16,  Local resources are insufficient to support another
                 connection;  the operation was suppressed
            20,  The connection attempt was rejected by the foreign
                 process
            24,  The specified local socket is not local to UCSB;  the
                 operation was suppressed
            28,  The specified foreign site is invalid;  the operation
                 was suppressed
            32,  An addressing or protection exception was encountered
                 with respect to the specified workspace;  the
                 operation was suppressed
            36,  Either hardware at the foreign site is inoperative or
                 the NCP's counterpart at the foreign site does not
                 exist or has failed
            40,  Local and foreign sockets are both either send or
                 receive sockets;  the operation was suppressed
            44,  By operator command, all Network operations were
                 terminated;  the socket will be closed
            60,  An NCP control transmission error occured;  the
                 operation was suppressed
           252,  The specified time limit was exceeded;  the operation
                 was initiated but not completed
   (B)  LISTEN
        This operation is a request for notification of any connection
        attempt  directed  toward  the  specified  local  socket.  The
        subprogram waits until such a call is received, at which  time
        the  calling  process'  socket  identifier  is returned to the
        calling program.   This  operation  is  valid  only  when  the
        designated  local  socket is in the closed state.  The calling
        sequence is as follows:
             CALL @OPEN(cmpcd, time,lclsck,ws);
        where
             'cmpcd' is the completion code variable to be associated
                  with the local socket.
             'time' is the length of time the subprogram is to wait
                  for the completion of the operation.
             'lclsck' is the socket identifier of the local socket.
             'ws' is a workspace which, if the operation is
                  successful, will contain the socket identifier of
                  the calling socket, and will become associated with
                                                              [Page 4]

RFC 120 NETWORK PL1 SUBPROGRAMS

                  the local socket for the life of the connection.
                  'ws' has the same attributes as a socket identifier.
        The  following  completion  codes  are   possible   for   this
        operation:
             0,  The operation was successful and a call has been
                 received
             4,  The specified completion code variable is already
                 assigned to a socket;  the operation was suppressed
             8,  The specified local socket is not in the closed
                 state;  the operation was suppressed
            12,  Local resources are insufficient to support another
                 connection;  the operation was suppressed
            16,  The specified local socket is not local to UCSB;  the
                 operation was suppressed
            20,  An addressing or protection exception was encountered
                 with respect to the specified workspace;  the
                 operation was suppressed
            44,  By operator command, all Network operations were
                 terminated;  the socket will be closed
           252,  The specified time limit was exceeded;  the operation
                 was initiated but not completed
   (C)  ACCEPT
        This operation accepts  connection  with  the  foreign  socket
        whose  call  caused successful completion of a previous LISTEN
        operation by the specified local socket.  After completion  of
        this  operation,  data may be transferred to or from the local
        socket, depending on its gender.  This operation is valid only
        when  the  last  operation  referencing the local socket was a
        LISTEN  operation.   The  subprogram  will  wait   until   the
        operation is completed.
        The calling sequence is as follows:
             CALL @OPEN(cmpcd, time);
        where
             'cmpcd' is the completion code variable associated with
                  the local socket by a previous LISTEN operation.
              'time' is the length of time the subprogram is to wait
                  for the completion of the operation.
        The  following  completion  codes  are   possible   for   this
        operation:
                                                              [Page 5]

RFC 120 NETWORK PL1 SUBPROGRAMS

             0,  The operation was successful, and the connection is
                 established
             4,  The specified local socket is in the closed state
                 (the NCP may have received an abort notification from
                 the foreign process);  the operation was suppressed
             8,  The previous operation specifying the designated
                 local socket was not a LISTEN;  the operation was
                 suppressed
            12,  All communication paths to the specified foreign site
                 are in use;  the socket has been returned to the
                 closed state
           252,  The specified time limit was exceeded;  the operation
                 was initiated but not completed

(2) CLOSE

   This operation is a request that  the  specified  local  socket  be
   returned to the closed state.  If the last operation involving this
   socket was a LISTEN, this operation refuses  the  foreign  process'
   connection  attempt.   If  the  last  operation  was a CONNECT, the
   attempt is aborted.  If a connection is established,  any  data  in
   transit  from  the  local  socket  is  allowed to reach the foreign
   socket and to be either received or flushed before the local socket
   is  closed.   The  subprogram  will  wait until the socket has been
   returned to the closed state.
   The calling sequence is as follows:
        CALL @CLOSE(cmpcd,time);
   where
        'cmpcd' is the completion code variable associated with the
             local socket.
        'time' is the length of time the subprogram is to wait for the
             completion of the operation.
   The following completion codes are possible for this operation:
        0,  The operation was successful, and the socket has been
            returned to the closed state
        8,  The specified completion code variable is not currently
            assigned to a socket;  the operation was suppressed
       12,  The specified local socket is in the process of being
            closed;  the operation was suppressed, but the local
            socket will be closed
       36,  Either hardware at the foreign site is inoperative, or the
            NCP's counterpart at the foreign site does not exist or
                                                              [Page 6]

RFC 120 NETWORK PL1 SUBPROGRAMS

            has failed
       44,  By operator command, all Network operations were
            terminated;  the socket will be closed
       60,  An NCP control transmission error occured;  the operation
            was aborted
       64,  A transmission error occured;  the operation was aborted,
            but the socket will be closed
      252,  The specified time limit was exceeded;  the operation was
            initiated but not completed

(3) SEND

   This operation causes data to be sent to the foreign  socket.   The
   subprogram  will  wait  until  the  data  has  been received by the
   foreign socket, or until it has been queued locally by the NCP.
   The calling sequence is as follows:
        CALL @WRITE(cmpcd, bfr,len,time[,offset]);
   where
        'cmpcd' is the completion code variable associated with the
             local socket.
        'bfr' is the data to be sent, and must be a singly dimensioned
             array, either DECIMAL or BINARY, FIXED or FLOAT.
        'len' is the number of bits of data to be sent.  If 'len' is
             non-positive, no operation is performed.  'len' has the
             attribute BINARY FIXED(31,0).
        'time' is the length of time the subprogram is to wait for the
             completion of the operation.
        'offset' is the bit offset from the first bit of 'bfr' at
             which data transmission is to begin, and must have the
             attributes BINARY FIXED(31,0).  If not specified,
             'offset' defaults to zero.
   The following completion codes are possible for this operation:
        0,  The operation was successful, and the data has been sent
        4,  The specified local socket is not a SEND socket;  the
            operation was suppressed
        8,  The specified completion code variable is not assigned to
            a socket;  the operation was suppressed
       12,  A previous SEND operation is in progress;  the operation
            was suppressed
       16,  The connection is not fully open;  the operation was
            suppressed
       20,  The foreign socket terminated the connection before
                                                              [Page 7]

RFC 120 NETWORK PL1 SUBPROGRAMS

            completion of the SEND operation;  not all data was
            transmitted
       36,  Either hardware at the foreign site is inoperative, or the
            NCP's counterpart at the foreign site does not exist or
            has failed
       44,  By operator command, all Network operations were
            terminated;  the socket will be closed
       52,  One or more interrupts were received from the foreign
            socket;  the operation was suppressed
       56,  An addressing exception was encountered with respect to
            the data buffer;  the operation was suppressed
       60,  An NCP control transmission error occured;  the operation
            was suppressed
       64,  A transmission error occured;  the operation was aborted,
            and the socket will be closed
      252,  The specified time limit was exceeded;  the operation was
            initiated but not completed

(4) RECEIVE

   This operation causes data to be received from the foreign  socket.
   The subprogram will wait until the reception of data is complete.
   The calling sequence is as follows:
        CALL @READ(cmpcd,bfr,len,time[,offset]);
   where
        'cmpcd' is the completion code variable associated with the
             local socket.
        'bfr' is the variable into which the data is to be placed, and
             must be a singly dimensioned array, DECIMAL or BINARY,
             FIXED or FLOAT.
        'len' is the number of bits of data to be received.  If 'len'
             is non-positive, no operation is performed.  'len' has
             the attribute BINARY FIXED(31,0).
        'time' is the length of time the subprogram is to wait for the
             completion of the operation.
        'offset' is the bit offset from the first bit of 'bfr' at
             which the first bit of data is to be placed, and must
             have the attributes BINARY FIXED(31,0).  If not
             specified, 'offset' defaults to zero.
   The following completion codes are possible for this operation:
        0,  The operation was successful and the data has been
            received
                                                              [Page 8]

RFC 120 NETWORK PL1 SUBPROGRAMS

        4,  The specified local socket is not a receive socket;  the
            operation was suppressed
        8,  The specified completion code variable is not assigned to
            a socket;  the operation was suppressed
       12,  A previous RECEIVE operation is in progress;  the
            operation was suppressed
       16,  The connection is not fully open;  the operation was
            suppressed
       20,  The foreign socket terminated the connection before
            completion of the RECEIVE operation;  data is
            unpredictable
       36,  Either hardware at the foreign site is inoperative, or the
            NCP's counterpart at the foreign site does not exist or
            has failed
       44,  By operator command, all Network operations were
            terminated;  the socket will be closed
       24,  An addressing or protection exception was encountered with
            respect to the data buffer;  the operation was suppressed
       52,  One or more interrupts were received from the foreign
            socket;  the operation was suppressed
       60,  An NCP control transmission error occured;  the operation
            was aborted, and the socket will be closed
      252,  The specified time limit was exceeded;  the operation was
            initiated but not completed

(5) CHECK

   This operation causes the status of the specified local  socket  to
   be  returned.  There is no completion code variable associated with
   this operation, since it is always successful  and  the  socket  is
   identified  by  its  socket number.  This operation is valid at any
   time and is always completed immediately.
   The calling sequence is as follows:
        CALL @CHECK(lclsck,stat,mnem,fgnsck,deficit);
   where
        'lclsck' is the socket identifier of the local socket.
        'stat' is a code for the status, and has the attribute BINARY
             FIXED(31,0).
        'mnem' is a mnemonic for the status, and has the attribute
             CHARACTER, of any fixed length greater than or equal to
             eight.  If 'mnem' is longer than eight bytes, it will be
             padded to the right with blanks.
        'fgnsck' is the socket identifier of the foreign socket, or
             zero.
                                                              [Page 9]

RFC 120 NETWORK PL1 SUBPROGRAMS

        'deficit' is the send/receive deficit in bits, or zero, and
             has the attributes BINARY FIXED(31,0).
        'lclsck' is the only argument the programmer need define;
            the others are output from the subprogram.
   Following are  the  possible  status  codes,  together  with  their
   mnemonics and interpretations.
        'STAT'  'MNEM'        MEANING
         ----    ----
           0    OPEN       A connection is fully established.  No
                           SEND/RECEIVE operation is in progress.
                           'fgnsck' is the socket identifier of the
                           connected socket.  'deficit' is the number
                           of bits queued locally at the socket by the
                           NCP and available to satisfy a future
                           RECEIVE operation, or awaiting output as
                           the result of a previous SEND operation.
           1    LISTEN     A LISTEN has been issued.
           2    CONNECT    A CONNECT has been issued.  'fgnsck' is the
                           socket identifier of the foreign socket.
           3    DECISION   A LISTEN has been completed.  'fgnsck' is
                           the socket identifier of the calling
                           socket.
           4    CALL(S)    One or more calls have been received for
                           the local socket.  No LISTEN or CONNECT has
                           been issued.
           5    I/O        A connection is fully established.  A
                           SEND/RECEIVE operation is in progress.
                           'fgnsck' is the socket identifier of the
                           connected socket.  'deficit' is the number
                           of bits yet to be sent or received.
           6    CLOSED     The socket is in the closed state.
           7    <--DRAIN   The foreign socket is attempting to close
                           the connection.  The NCP has data yet to be
                           read by the local socket.  'fgnsck' is the
                           socket identifier of the connected socket.
                           'deficit' is the number of bits yet to be
                           received.
                                                             [Page 10]

RFC 120 NETWORK PL1 SUBPROGRAMS

           8    DRAINED    The foreign socket is attempting to close
                           the connection.  The NCP is awaiting
                           arrival at the foreign site of data
                           currently in transit.  'fgnsck' is the
                           socket identifier of the connected socket.
           9    CLOSING    The local socket has issued a CLOSE.  The
                           NCP is in the process of returning the
                           local socket to the closed state.  'fgnsck'
                           is the socket identifier of the connected
                           socket.
          10    DRAIN-->   The local socket has issued a CLOSE.  The
                           NCP is completing the last SEND operation
                           before returning the local socket to the
                           closed state.  'fgnsck' is the socket
                           identifier of the connected socket.
                           'deficit' is the number of bits the NCP has
                           yet to transmit.

(6) IDENTIFY

   This operation is used to identify a local socket by its completion
   code  variable.   The operation is valid at any time, and is always
   completed immediately.  Since it is always successful, there are no
   completion  codes  for  the  operation,  and  the  contents  of the
   completion code variable are not changed.
   The calling sequence is as follows:
        CALL @ID(cmpcd,lclsck);
   where
        'cmpcd' is the completion code variable to be associated with
             the local socket
        'lclsck' is set to the socket identifier of the local socket
             if the completion code variable is associated with a
             socket, or to zero otherwise.

(7) SIGNAL

   This operation is used to convey a signal to the  foreign  process.
   The  significance  of the signal is completely user-dependent.  The
   effect is that  the  next  time  the  foreign  socket  attempts  to
   initiate  a  RECEIVE  or  SEND  operation,  the  operation  will be
   suppressed, and a completion code supplied indicating that a signal
   had  been  received.  The subprogram will wait until the signal has
                                                             [Page 11]

RFC 120 NETWORK PL1 SUBPROGRAMS

   been sent to the foreign NCP.  This operation is  valid  only  when
   the socket is fully open.
   The calling sequence is as follows:
        CALL @ID(cmpcd,time);
   where
        'cmpcd' is the completion code variable associated with the
             local socket.
        'time' is the length of time the subprogram is to wait for
             completion of the operation.
   The following completion codes are possible for this operation:
        0,  The operation was successful, and the signal has been sent
        4,  The specified completion code variable is not assigned to
            a socket;  the operation was suppressed
        8,  The connection is not fully open; the operation was
            suppressed
 Certain of the Network subprograms are  intended  for,  although  not
 restricted  to,  use  with the On-Line System Network operators.  The
 following is a general description of these operators:
 In all  Network  operations  involving  the  On-Line  System  Network
 operators, there are certain conventions concerning the format of the
 data sent and received.  The data is grouped in 'messages' consisting
 of  three  fields,  op code, length, and text, in that order.  The op
 code is one byte in length and is a code which indicates how the text
 field  is to be interpreted.  The length field is two bytes long, and
 gives the length, in bits, of the  text  field,  which  contains  the
 actual  data.   (The  op code and length fields together are termed a
 header.)
 The following op codes are presently defined:
   op code        meaning
      0     The op code is a NOP.  No text field exists, and the
            contents of the length field are unpredictable.  (This op
            code is used mainly as a delimiter.)
      1     The text field contains EBCDIC characters, one character
            per byte.  The On-Line System Network operators consider
            the characters as intended for display as soon as the
            text field has been received.
                                                             [Page 12]

RFC 120 NETWORK PL1 SUBPROGRAMS

      2     The text contains codes for keypushes, one byte per key.
            The On-Line operators consider the text as intended for
            execution as soon as the text field has been received.
      3     The same as for an op code of 2, except that the On-Line
            operators consider that the execution of the keys will be
            delayed until all data for that receive operation has
            been received.
 The standard format of data sent or received by  the  On-Line  System
 operators is a string of messages, with the last message indicated by
 a header with a NOP op code, called a trailer.  These conventions are
 the  default  situation; any of them may be overridden by appropriate
 programming.
 Following are descriptions of those subprograms intended for use with
 the On-Line System operators.

(8) WRITE TO ON-LINE CONSOLE

   This subprogram causes data, assumed to be  characters  represented
   by  their EBCDIC codes, to be sent from the specified local socket.
   The characters are sent  in  a  standard  message,  preceded  by  a
   header, and optionally followed by a trailer.  The subprogram waits
   for the data to be received by the foreign socket, or to be  queued
   locally  by  the  NCP.  This operation is valid only when the local
   socket is a send socket, and is fully open.
   The calling sequence is as follows:
        CALL @WTOLC(cmpcd,bfr,len,level,across,down,time);
   where
        'cmpcd' is the completion code variable associated with the
             local socket.
        'bfr' is the character string to be sent, and must have the
             attribute STRING, either CHARACTER or BIT, of any length,
             fixed or varying.
        'len', in absolute value, is the number of characters to be
             sent.  If 'len' is positive or zero, the end of the data
             is indicated by a trailer;  if 'len' is negative, no
             trailer is sent.  'len' has the attributes BINARY
             FIXED(31,0).
        'level' indicates the mode of typing.  The absolute value of
             'level', if non-zero, is the shift level on which to
             type, and must be less than or equal to nine.  If greater
             than nine, one is used.  If 'level' is positive, 'across'
                                                             [Page 13]

RFC 120 NETWORK PL1 SUBPROGRAMS

             and down are relative to the current typing location.  If
             'level' is negative, the carriage is positioned to the
             upper left-hand corner before typing begins, thus making
             'across' and 'down' absolute coordinates.  If 'level' is
             zero, the typing is in case one characters, and a
             carriage return precedes the positioning for 'across' and
             'down'.  If the characters to be displayed are case one
             characters, the header sent will have an op code which
             indicates characters to be displayed as soon as they are
             received;  otherwise, the op code will indicate buttons
             to be executed as soon as received.  'level' has the
             attributes BINARY FIXED(31,0).
        'across' is the number of spaces to be moved horizontally
             across the display tube before beginning to type.
             'across' can have any value, positive, negative, or zero,
             and has the attributes BINARY FIXED(31,0).
        'down' is the number of lines to be moved vertically down the
             display tube before beginning to type.  'down' can have
             any value, positive, negative, or zero, and has the
             attributes BINARY FIXED(31,0).
        'time' is the length of time the subprogram is to wait for the
             completion of the operation.
   The completion codes for this operation are the same as for SEND.

(9) READ FROM ON-LINE CONSOLE

   This subprogram receives data, assumed to be characters represented
   by  their  EBCDIC  codes,  from  the  foreign socket in one or more
   standard  messages.   The  subprogram  will  wait  for  the   data,
   optionally  followed  by  a  trailer,  to  be received by the local
   socket.  This operation is valid only when the local  socket  is  a
   receive socket and is fully open.
   The calling sequence is as follows:
        CALL @RFOLC(cmpcd,bfr,len,time);
   where
        'cmpcd' is the completion code variable associated with the
             local socket.
        'bfr' is the variable into which the data is to be placed, and
             has the attribute CHARACTER, of any fixed length.  If the
             length of 'bfr' is greater than the amount of data
             received, 'bfr' will be padded to the right with blanks.
        'len', in absolute value, is the maximum number of characters
             to be placed in 'bfr'.  If the length fields of the
                                                             [Page 14]

RFC 120 NETWORK PL1 SUBPROGRAMS

             header(s) received total more data than 'len', the excess
             data will be received, but will not be placed into 'bfr',
             and will not be accessible to the program.  If 'len' is
             positive or zero, data will be received until a trailer
             is encountered.  If 'len' is negative, a single message,
             exclusive of trailer, will be received.  'len' has the
             attributes BINARY FIXED(31,0).
        'time' is the length of time the subprogram is to wait for the
             completion of the operation.
   The completion codes  for  this  operation  are  the  same  as  for
   RECEIVE.

(10) WRITE TO ON-LINE CONSOLE WITH REPLY

   This  subprogram  combines  the  functions  of  'WRITE  TO  ON-LINE
   CONSOLE'  and  'READ  FROM  ON-LINE CONSOLE'.  The subprogram first
   sends a string of data to the foreign  socket  from  the  specified
   send  socket, waits for it to be received by the foreign socket (or
   queued locally by the NCP), and then waits  for  a  reply  directed
   toward  the  specified receive socket.  The operation is valid only
   when the sockets have the correct gender and both are fully open.
   The calling sequence is as follows:
        CALL @WTOLCR(cmpcd, bfr, len, level, across, down, time,
                     cmpcd2, bfr2, len2);
   where
        'cmpcd' is the completion code variable associated with the
             local send socket.
        'bfr' is as in 'WRITE TO ON-LINE CONSOLE'.
        'len' is as in 'WRITE TO ON-LINE CONSOLE'.
        'level' is as in 'WRITE TO ON-LINE CONSOLE'.
        'across' is as in 'WRITE TO ON-LINE CONSOLE'.
        'down' is as in 'WRITE TO ON-LINE CONSOLE'.
        'time' is the length of time the subprogram is to wait for
             completion, individually, of the transmission and
             reception of data.
        'cmpcd2' is the completion code variable associated with the
             local receive socket.
        'bfr2' is as 'bfr' in 'READ FROM ON-LINE CONSOLE'.
        'len2' is as 'len' in 'READ FROM ON-LINE CONSOLE'.
   The completion codes for the send socket are the same  as  for  the
   SEND operation, and the completion codes for the receive socket are
   the same as for the RECEIVE operation.
                                                             [Page 15]

RFC 120 NETWORK PL1 SUBPROGRAMS

(11) ERASE

    This subprogram causes data constituting an On-Line System command
    to  erase  the  display  tube  to be sent from the specified local
    socket.  The data is sent in a single standard message,  including
    an  op  code  indicating  characters  to  be displayed as they are
    received, and optionally  including  a  trailer.   The  subprogram
    waits  for the data to be received by the foreign socket, or to be
    queued locally by the NCP.  This operation is valid only when  the
    local socket is a send socket, and is fully open.
    The calling sequence is as follows:
         CALL @ERASE(cmpcd,delay1,delay2,time);
    where
         'cmpcd' is the completion code variable associated with the
              local socket.
         'delay1', in absolute value, is the length of time, in tenths
              of a second, the subprogram is to pause (in the WAIT
              state) before sending the erase.  If 'delay1' is
              positive or zero, a trailer will be sent after the
              erase;  if negative, no trailer will be sent.  'delay1'
              has the attributes BINARY FIXED(31,0).
         'delay2', is the length of time, in tenths of a second, the
              subprogram is to pause after sending the erase and
              before returning control to the calling program, and has
              the attributes BINARY FIXED(31,0).
         'time' is the length of time the subprogram is to wait for
              the completion of the operation.
    The completion codes for this operation are the same as for SEND.
        [ This RFC was put into machine readable form for entry ]
         [ into the online RFC archives by Rune Skaarsmoen 6/97 ]
                                                             [Page 16]
/data/webs/external/dokuwiki/data/pages/rfc/rfc120.txt · Last modified: 1997/06/24 16:01 (external edit)