PIN - Procedure Interpreter
		===========================

			Users' Guide
			============

 The  Indirect  Command  File  Processor  (AT.)  is  an  exceptionally
 flexible  and  useful program. Unfortunately it is also very big, and
 for  the  user  who  only  wishes  to  use  it to do compilations and
 taskbuilds  (or  suchlike) sequentially on a small system can be very
 inefficient in terms of system resources. PIN (PROCEDURE INTERPRETER)
 is  a  task 1/4 the size of the Indirect File processor which is used
 identically  to  ...AT. to control the assembly and taskbuild process
 during  program development. It does not recognize the special ...AT.
 commands  but  only  accepts  one  line MCR type commands (and a very
 limited  number  of special PIN commands). If during the execution of
 any command a fatal error is encountered, PIN will cease execution of
 the  command  file  and  allow  the user to correct the problem - the
 command  line  creating  the  error  is  displayed. By default, other
 command  lines  are  not displayed. PIN assumes that the command file
 given  to  it  will  have  the  extension  .CMD,  but  if a different
 extension  is  explicitly used, PIN will use that name in looking for
 the command file. 

 PIN is invoked by typing

	PIN cmdfile

 where  cmdfile  is  a commandfile (default extension .CMD) containing
 ordinary MCR commands and, optionally, special PIN commands.

 PIN  allows  a  small  number  of internal commands, specified in the
 commandfile, as follows:-

 	$DE	    - delete the .CMD file on closing 
	$NODE	    - do not delete the .PRC file on closing
	$TR	    - print each command as it is executed
	$NOTR	    - do not print each command.
	$CH cmdfile - chain to file 'cmdfile'
 
 Initially PIN starts out with NOTR & NODE.


 PIN may report one of the following error messages:-

 1.  PIN - SYNTAX ERROR

     The  commandline  contained  less  than four characters - i.e. no
     commandfile was specified.

 2.  PIN - ILLEGAL FILE NAME

     PIN could not parse the specified file.  Correct the filename and
     respecify the line.


 3.  PIN - FILE OPEN ERROR

     PIN  could  not open the specified file.  Correct the problem and
     submit the line.

 4.  PIN - NO SUCH FILE

     The  specified  commandfile  does  not  exist.  Resubmit the line
     specifying a valid filename.

 5.  PIN - SPAWN FAILURE

     The Spawn directive failed - probably because it was not included
     in  the  System Generation.  PIN cannot operate without the Spawn
     Directive.

 6.  PIN - STOP FOR EVENT FLAG FAILED

     The  'Stop for Event Flag' directive failed - probably because it
     was  not  included  in the System Generation.  PIN cannot operate
     without the Stop for Event Flag Directive.

 7.  PIN - WARNING, EXIT WITH NON-FATAL ERROR

     A  command  spawned  by PIN resulted in a 'non-fatal' exit status
     (2).  PIN prints out the current line and continues.

 8.  PIN - FATAL, EXIT WITH SEVERE ERROR

     A  command  spawned by PIN resulted in a 'fatal' exit status (4).
     PIN prints out the current line and exits.

 9.  PIN - CMD FILE READ ERROR

     An  error was detected while reading the command file.  Check the
     file and resubmit it if necessary.

 10. PIN - CMD FILE CLOSE ERROR

     An  error was detected while closing the command file.  Check the
     file to determine the cause of the error.

 11. PIN - ONLY SINGLE LINE MCR COMMANDS ALLOWED

     A  command  line  was  detected  that was not a valid MCR command
     line,  nor  an  internal  command.  Remove the offending line and
     resubmit the commandfile.

 12. PIN - UNKNOWN INTERNAL COMMAND

     A  command line was detected that started with a $ (indicating an
     internal  command)  but  which  did  not contain a valid internal
     command.  Correct the offending line and resubmit the commandfile.

		PIN - Procedure Interpreter
		===========================

			System Guide
			============

 PIN is very simple in construction.  It obtains the MCR command line,
 parse  the  filename given via ASCFNM, and accesses the file for read
 via  F11ACP  QIO  primitives.   It then reads each record in the file
 (performing  its  own deblocking), checks to see if it is an internal
 command  and  if  not  (  and  it is valid for MCR) spawns it to MCR,
 checking  the  exit status and acting accordingly.  When all commands
 are processed it deaccesses the file and exits.

 It  handles  all  the  internal  commands  other  than  $CH by simply
 setting/clearing    tracing/deletion  flags  which  are  tested  when
 required.    On  encountering  a $CH it simply deaccesses the current
 file  and  branches back to treat the line as if it had been typed in
 the first place.

 PIN is a non-privileged task with a taskname of ...PIN, using 2 units
 (Unit  1  should be assigned to SY: and Unit 2 to TI:) and a stack of
 20.