To use the very old PASCAL compiler, say "R OPASCAL".

To use the old version (Feb-78) say "R PASOLD"

To use the new PASCAL compiler, use COMPILE class commands such as
"EXECUTE FOO.PAS/LIST".

To use the Hedricks Pascal, "R PSC", followed by "OBJ,LIST=SOURCE".  If
you omit the name of the object file, you won't get one.  If you are debugging
a multiple-module program, you must load PSDDT, e.g.
   LOAD SYS:PSDDT,DSK:MOD1,MOD2,MOD3/LINK

For more information and pointers to further documentation, say
"READ PASCAL", or (from a non-display) "TYPE PASCAL.ARR[UP,DOC]".