Bitfields for Intel PIIX4 ISA I/O recovery timer:
Bit(s)	Description	)
 7	disable aliasing PORTs 90h-9Fh into 80h-8Fh (except PORT 0092h)
 6	enable 8-bit I/O recover timer in bits 5-3
 5-3	additional 8-bit I/O recovery time (added to 3.5 SYSCLK minimum)
	000 = 8 SYSCLKs, else N SYSCLKs
 2	enable 16-bit I/O recovery timer in bits 1-0
 1-0	additional 16-bit I/O recovery time (added to 3.5 SYSCLK minimum)
	00 = 3 SYSCLKs
	01 = 1 SYSCLK
	10 = 2 SYSCLKs
	11 = 4 SYSCLKs
SeeAlso: #01100