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CALC Ver. 1  was never released.
This release replaces Ver. 2 (DECUS No. 20-7).

CALC Ver. 3 is functionally identical to Ver. 2, with the exception
of the following fix and the improvement to MCR20 detailed below.

	- CALC Ver. 2 would print an error when trying to calculate
	  SQRT(.1)-2. It was found that the precedence of stack
	  operations were not proper, causing this error. It has 
	  been fixed.

	- Ver. 2 required that the user be CONNECTed to the directory
	  containing CALC.EXE in order to use CALC. This has been
	  rectified by a rewrite of MCR20 and minor changes to 
	  CALC.FOR (the main program). MCR20 is a MACRO-20 subroutine
	  which obtains the command line from TOPS-20. It checks the
	  line and decides if the run is a one-shot or a continuous
	  session. If it's a one-shot, MCR20 returns the argument
	  (CALC expression hopefully) to the calling program.

	  The following examples will cause CALC to evaluate the
	  given expression and exit immediately:

	  @CALC 2+2
	  @CALC SQRT(3*3+4*4)
	  @CALC (-8+SQRT(8*8-4*1*16))/(2*1)

	  The following examples will cause CALC to enter continuous
	  mode, prompting with   CALC>   

	  @CALC				(no argument)


	  MCR20 uses the TOPS-20 COMND JSYS and parses for a file 
	  name. Thus CALC may be renamed and/or MCR20 could be utilized
	  by other programs.
	  It should be noted that the syntax:
	  @RUN CALC expression 
	  is disallowed by TOPS-20 (Ver. 3 at this writing) and thus
	  by extension, disallowed by CALC.