PORTIBM PC Portable (uses same BIOS as XT) 3518-351B - ESDI(Enhanced Small Device Interface) A disk drive interface type which was briefly popular before IDE took over. An ESDI drive can transfer data between the drive and controller at 10, 15, or 20 megabits per second, which is faster than an MFM or RLL controller but slower than what is possible with an IDE or SCSI drive. See also IDE. secondary harddisk controller Range: PORTIBM PC Portable (uses same BIOS as XT) 3510h-3513h (primary) or PORTIBM PC Portable (uses same BIOS as XT) 3518h-351Bh (secondary) SeeAlso: PORTIBM PC Portable (uses same BIOS as XT) 3510h,PORTIBM PC Portable (uses same BIOS as XT) 01F0h-01F7h 3518w R- status word 3518w -W command word 351A R- basis status 351A -W basic control 351B R- interrupt status 351B -W attention