8087(HW) XENIX System V 8087(HW)
Name
8087
Syntax
8087
80287
Description
The 8087 is the INTEL math co-processor for the 8086. The
80287 is the INTEL math co-processor for the 80286. The
kernel tests for the presence of an 8087 or 80287 at
startup.
If your system has an 8087 or 80287, you must turn off a
switch main system board in order to enable 8087 interrupts.
Check you hardware manual to determine the proper switch and
setting. If your system does not have an 8087, or the
switch is on, the kernel will run a set of emulator routines
which are much slower.
The C compiler available with the program development
package generates the appropriate 8087 (or 80287) opcodes.
C routines compiled with this compiler have run as much as
200 times as fast as the emulated code. In particular, the
standard math library routines run considerably faster if
you have an 8087 (or 80287).
The overflow, division by zero, and invalid operand
exceptions return a SIGFPE signal. This signal can be
caught. The rest of the 8087 and 80287 floating point
exceptions (underflow, denormalized operand, and precision
error) are masked.
Notes
The emulator returns meaningless information on divide by
zero.
There is no obvious way to tell which 8087 (or 80287)
exception generated the SIGFPE.
Page 1 (printed 8/7/87)
