read_me

早期freebsd实现

# @(#)READ_ME	8.1 (Berkeley) 6/6/93

   This directory contains the source code for the Version 7 VAX
interpreter for Pascal. Following standard convensions, the makefile
contains four commands:

	px - compile px

	install - compile and install px in /usr/ucb

	clean - clean out directory

	print - print out a listing of px



Bugs and Limitations:

   Runtime error messages could give far more information than they
currently do. (eg the actual value of a subscript which is out
of range)

   It should be possible to resume execution following many of
the runtime errors. (eg fixed overflow, interrupt, etc)


Comparison of Pascal with C compiler

In an attempt to compare compiled versus interpreted execution speeds
the 'Tower of Hanoi' benchmark (see hanoi.p, hanoi.c) was run with 
the following results:

Data:
	number of disks: 		   16
	number of moves required:	65535

Compiler, Flags		  Compile	Compile		 Run	 Run
			   Time		 Factor		 Time	Factor
Pi, full tests		 0.4u+0.4s	  1.0		42.7u	  1.0
Pi, no tests		 0.3u+0.3s	  0.7		35.2u	  1.2
Pc, unoptimized		 3.8u+2.4s	  7.7		 5.3u	  8.1
Pc, optimized		 4.4u+2.3s	  8.4		 4.6u	  9.3
C, unoptimized		 1.7u+1.8s	  4.4		 2.8u	 15.3
C, optimized		 2.0u+2.0s	  5.0		 2.5u	 17.1

Note: The times for Pc and C were obtained by running larger
problems and scaling the run times down appropriately.