This directory contains the source code for the Version 7 VAX
interpreter for Pascal. Following standard convensions, the makefile
px - compile and load px.
install - compile px and install it in /usr/ucb
clean - clean out directory
print - print out a listing of px
Output of reals of value less than 1 does not print out a leading
zero. (eg 1.0e-01 prints as .1 rather than 0.1)
Pi does not compute stdio format strings, so they must be computed
at run time. (see 31writeold.s for details)
Runtime error messages could give far more information than they
currently do. (eg the actual value of a subscript which is out
It should be possible to resume execution following many of
the runtime errors. (eg fixed overflow, interrupt, etc)
Comparison of Pascal interpreter 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
number of moves required: 65535
Pascal, no tests 38.2 15.3
Pascal, full tests 57.1 22.8
Note: The times for the C programs were obtained by running
larger problems and scaling them down appropriately.
Berkeley is developing a Pascal compiler which should improve the
runtime by about a factor of 10.