PORTIBM PC Portable (uses same BIOS as XT) 00F0-00FF - MATH COPROCESSOR (8087..80387)

00F0  -W  math coprocessor clear busy latch (write 00h)
00F1  -W  math coprocessor reset (write 00h)
00F8  RW  opcode transfer (CPU-coprocessor communication)
00FA  RW  opcode transfer
00FC  RW  opcode transfer