Microsoft KB Archive/36899

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Knowledge Base

Article ID: 36899

Article Last Modified on 11/21/2006

This article was previously published under Q36899


In QuickBasic Versions 4.00 and 4.00b, BC.EXE correctly gives you an "Option Unknown" error message if you compile with the BC /FPa option.

In QuickBasic Version 4.50, BC.EXE gives no error when you compile with the BC /FPa option. However, you will get an error about the missing Alternate Floating Point Math library at link time, since this library is NOT supplied with QuickBasic Version 4.50. The alternate math library is supplied only when you purchase either Microsoft Basic Compiler Version 6.00 or 6.00b for MS-DOS and MS OS/2 or Microsoft Basic PDS Version 7.00 for MS-DOS or MS OS/2.

The /FPa option is not documented in the QuickBasic Version 4.50 package since it is not tested or supported there.


The BC.EXE Version 4.50 /FPa option actually may generate correct code for the option. One customer reported that a program worked correctly when linked with .OBJ files from both QuickBasic Version 4.50 and the Basic compiler Version 6.00, all compiled with /FPa.

However, Microsoft has not tested using the /FPa option with BC.EXE Version 4.50 and linking with the Alternate Floating Point Math Library taken from the Basic compiler Version 6.00 or 6.00b. We do not guarantee or support this combination.

If you want to use the /FPa option, you must compile all .OBJ files in the Basic compiler Version 6.00 or 6.00b, or in BC.EXE 7.00, which comes with Basic PDS Version 7.00.

Switches Specific to Basic PDS 7.00

Several other compiler switches are supported in BC.EXE 7.00, which comes with Basic PDS version 7.00, that are NOT supported in BC.EXE 4.00, 4.00b, 4.50, 6.00, or 6.00b. They are the following:

/G2 /Ot /Lr /Lp and /Fs

Each of these produces the "Option unknown: " error if you try to compile with the BC.EXE 4.00, 4.00b, 4.50, 6.00, or 6.00b compilers.

One situation where you could unexpectedly receive the "Option unknown: " error is when you choose to compile or "Make .EXE" from within QBX.EXE. Suppose you are working in a directory or subdirectory that does not have the BC.EXE 7.00 compiler in it. If you choose to compile from within QBX.EXE, and QBX.EXE finds a BC.EXE 4.00, 4.00b, 4.50, 6.00, or 6.00b compiler on the MS-DOS PATH before it finds the BC.EXE 7.00 compiler, then you will receive this error message. It may take QBX.EXE as long as 25 seconds before it will prompt you with the "Press any key to continue" message, which allows you to return to the QBX.EXE environment and continue. This may make QBX.EXE appear to hang.

Additional query words: QuickBas

Keywords: KB36899