A.5.327 WAIT: Wait for Floating-Point Processor
WAIT ; 9B [8086]
FWAIT ; 9B [8086]
WAIT, on 8086 systems with a separate 8087 FPU, waits for the FPU to
have finished any operation it is engaged in before continuing main
processor operations, so that (for example) an FPU store to main memory
can be guaranteed to have completed before the CPU tries to read the
result back out.
On higher processors, WAIT is unnecessary for this purpose, and it
has the alternative purpose of ensuring that any pending unmasked FPU
exceptions have happened before execution continues.