General Questions
Is
Visual Prolog compatible with my old PDC Prolog for DOS projects?
Yes, Visual Prolog 5 contains the latest version of our DOS command line
compiler. The format for external Prolog databases (disk and RAM based) has
been improved to allow very large databases (> 1 GB). The DOS compiler can
be used with the PharLap DOS Extender.
Release 5.0 of Visual Prolog is nearly 100% compatible with release 4.0 and
4.1. We have added some new predicates, renamed a single predicate, carefully
modified the behavior of a couple of VPI predicates and moved some VPI header
files into subdirectories.
Before using the new Visual Prolog 5.xx please, back up all your files to a
safe place!
- The Year 2000 ("y2k") problem (popular called the
"Millennium Bug") arises from the use of a two-digit field to
identify years in computer programs (for example 85 = 1985), and the
assumption of a single century -- the 1900s. Any software so created will
read (or attempt to read) e.g. "00" as the year 1900. Programs
that use dates will fail or malfunction if these errors are not corrected.
- Visual Prolog 5.0 introduces - as far as PDC knows - no problems
concerning the Year 2000 problem. The only date-related functions in the
core language allow for setting and reading the current date from or to the
underlying operating system, and thus, with respect to these functions, you
should verify the Year 2000 compliance of the underlying operating system.
The Visual Prolog programming language defines no particular representation
for storing dates within an application, therefore, we can make no specific
warranties about the year-2000 compliance of applications developed in
Visual Prolog, since these will be year 2000 compliant or not, depending on
date representation and data-handling choices made by the application
programmer.
- Note that both the underlying operating system and the computer where the
program is running can also cause problems. We recommend that all
applications be carefully tested to see how they behave around and after the
millennium change.
- Note that Visual Prolog 5.xx includes a tool package DATE placed in
..\VPI\INCLUDE\DATE subdirectory. Date module is a collection of useful
predicates for converting of different date and time formats into each
other. It supplies application programmer with powerful methods to make
different calculations with dates including support for the date and time
format strings.
- Component technology is the main issue for VIP 6.0. However, you
can find some useful information in our examples in the
..\VPI\EXAMPLES\MSCOM
subdirectory.
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