80287 Emulation Limitations for 16-Bit Applications

SUMMARY

The 80287 emulation provided for support of 16-bit applications is limited in range to the support provided by the MIPS R4000 FPU. Thus there is a small range of numbers at the extreme ranges of the 80287's available numbering system that are not usable under the provided emulation.

These are the supported ranges:

                   Maximum                  Minimum
                   -------                  -------
Short real         3.40282e+38              1.17549e-38
Long & temp real   1.797631+308             2.22507e-308
				

NOTE: The R4000 FPU does not support temp real format. Temp real arithmetic on the emulated 80287 is performed as long real. The 80287's temp real format extends beyond these supported ranges, and therefore some applications may use numbers outside the above range to derive user-entered numbers. This can add an additional restriction to the above. For example, in Microsoft Access, the smallest long real (double) value that Microsoft Access accepts is 1e-301.