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Annotation of 3BSD/cmd/px/READ_ME, revision 1.1.1.1

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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