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General Questions

What are Visual Prolog restrictions?
How to get registry information using VIP?
Does Visual Prolog support multithreading?
Where can I find descriptions of error messages I get?
When I try to compile some examples and my own programs, I usually get an answer from Visual Prolog that it is impossible to compile, because a file or a disk is read-only.
Is Visual Prolog compatible with my old PDC Prolog for DOS projects?

Is Visual Prolog 5.xx  compatible with release 4.0 and 4.1?

Is Visual Prolog 5.X   2000 Year Compliant?

Does Visual Prolog allow calling COM objects?

Does Visual Prolog work with Sun Microsystems Inc. Solaris operating system?

What are known Visual Prolog hardware and software incompatibilities?

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.

Is Visual Prolog 5.xx  compatible with release 4.0 and 4.1?

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!

Is Visual Prolog 5.X   2000 Year Compliant?

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.

Does Visual Prolog allow calling COM objects?

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.