7.7 Using the NO87 Environment Variable

Programs compiled using either the calls to emulator (/FPc) or the inline emulator (/FPi) option automatically use an 80x87 coprocessor at run time if one is installed. You can override this and force the use of the software emulator by setting an environment variable named NO87.

Summary: Use the NO87 environment variable to suppress use of the 80x87 coprocessor at run time.

If NO87 is set to any value when the program is executed, use of the coprocessor is suppressed. The value of the NO87 setting is printed on the standard output as a message. The message is printed if a coprocessor is present and suppressed, or if no coprocessor is present.

You can set an environment variable by using the SET command from the command line. For example,

SET NO87=Use of coprocessor suppressed

This command causes the message Use of coprocessor suppressed to appear when a program that uses an emulator library is executed. If you don't want a message to be printed, set NO87 equal to one or more spaces. A blank string for NO87 causes a blank line to be printed.

Note that only the presence or absence of the NO87 definition is important in suppressing use of the coprocessor. The actual value of the NO87 setting is used only for printing the message.

The NO87 variable takes effect with any program linked with an emulator library (mLIBCE.LIB). It has no effect on programs linked with math coprocessor libraries (mLIBC7.LIB) or on programs linked with alternate math libraries (mLIBCA.LIB).