PORTIBM PC Portable (uses same BIOS as XT) 3510-3513 - 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. primary 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) 3518h,PORTIBM PC Portable (uses same BIOS as XT) 01F0h-01F7h 3510w R- status word 3510w -W command word 3512 R- basic status 3512 -W basic control 3513 R- interrupt status 3513 -W attention