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Annotation of 3BSD/cmd/px/READ_ME, revision 1.1

1.1     ! root        1:    This directory contains the source code for the Version 7 VAX
        !             2: interpreter for Pascal. Following standard convensions, the makefile
        !             3: contains four commands:
        !             4: 
        !             5:        px - compile and load px.
        !             6: 
        !             7:        install - compile px and install it in /usr/ucb
        !             8: 
        !             9:        clean - clean out directory
        !            10: 
        !            11:        print - print out a listing of px
        !            12: 
        !            13: 
        !            14: 
        !            15: Bugs and Limitations:
        !            16: 
        !            17:    Output of reals of value less than 1 does not print out a leading
        !            18: zero. (eg 1.0e-01 prints as .1 rather than 0.1)
        !            19: 
        !            20:    Pi does not compute stdio format strings, so they must be computed
        !            21: at run time. (see 31writeold.s for details)
        !            22: 
        !            23:    Runtime error messages could give far more information than they
        !            24: currently do. (eg the actual value of a subscript which is out
        !            25: of range)
        !            26: 
        !            27:    It should be possible to resume execution following many of
        !            28: the runtime errors. (eg fixed overflow, interrupt, etc)
        !            29: 
        !            30: 
        !            31: 
        !            32: Comparison of Pascal interpreter with C compiler
        !            33: 
        !            34: In an attempt to compare compiled versus interpreted execution speeds
        !            35: the 'Tower of Hanoi' benchmark (see hanoi.p, hanoi.c) was run with 
        !            36: the following results:
        !            37: 
        !            38: Data:
        !            39:        number of disks:                   16
        !            40:        number of moves required:       65535
        !            41: 
        !            42: Program                        Run Time        Factor
        !            43: C, optimized              2.5            1.0
        !            44: C, unoptimized            2.8            1.1
        !            45: Pascal, no tests         38.2           15.3
        !            46: Pascal, full tests       57.1           22.8
        !            47: 
        !            48: Note: The times for the C programs were obtained by running
        !            49: larger problems and scaling them down appropriately.
        !            50: 
        !            51: Berkeley is developing a Pascal compiler which should improve the
        !            52: runtime by about a factor of 10.

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