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a55523f1 CH |
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. |