MirOS Manual: npx(4)

NPX(4)                  BSD Programmer's Manual (i386)                  NPX(4)

NAME

     npx - Numeric Processing Extension coprocessor and emulator

SYNOPSIS

     option GPL_MATH_EMULATE
     npx0 at isa? port "IO_NPX0" irq 13

DESCRIPTION

     The npx driver enables the use of the system's Numeric Processing Exten-
     sion coprocessor, if one is present. Numeric processing extensions are
     present in systems with 486DX CPUs and in systems with 387 or 487SX
     coprocessors. The npx driver is required for proper system functioning
     regardless of whether or not a NPX is present.

     If there is no NPX present in the system option GPL_MATH_EMULATE must be
     defined in the kernel configuration file. It will provide support for the
     instructions normally executed by the NPX. If there is no NPX in the sys-
     tem and the kernel is not built with math emulation, the system will not
     boot.

SEE ALSO

     intro(4), isa(4)

CAVEATS

     The emulator is much slower than the NPX coprocessor. This will result in
     poor floating-point math performance if the emulator must be used.

BUGS

     There are lots of them, especially on cheap motherboards. In particular,
     some motherboards do not have the interrupt lines from the NPX to the CPU
     wired properly. If this is the case, the emulator must be used if con-
     sistent system operation is desired.

     Emulation of the transcendental functions instructions is incorrect. Emu-
     lation of other instructions is suspect.

MirOS BSD #10-current           August 6, 1993                               1

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