PORTIBM PC Portable (uses same BIOS as XT) 0170-0176 - OPTi "Vendetta" (82C750) CHIPSET - SECONDARY IDE(Integrated Drive Electronics) A type of disk drive interface which essentially extends the PCIBM PC's expansion bus all the way to the drive and places the drive controller on the disk drive itself.	 See also ESDI. CONTROLLER
Note:	to unlock access to these ports, you must perform two immediately
	  successive 16-bit INs from PORTIBM PC Portable (uses same BIOS as XT) 0171h, followed by 8-bit OUT of 03h
	  to PORTIBM PC Portable (uses same BIOS as XT) 172h
SeeAlso: PORTIBM PC Portable (uses same BIOS as XT) 01F0h"Vendetta"

0170  RW  read cycle timing register (see #P0536)
0171  RW  write cycle timing register (see #P0537)
0172  RW  internal ID register (see #P0538)
0173  RW  control register (see #P0539)
0175  RW  strap register (see #P0540)
0176  RW  miscellaneous register (see #P0541)