PORTIBM PC Portable (uses same BIOS as XT) 0073 - Intel 82378IB ("Saturn"/"Neptune" chipsets) - MBOARD CONFIGURATION SeeAlso: PORTIBM PC Portable (uses same BIOS as XT) 0075h 0073 RW ??? bit 7: ??? bit 6: disable ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs. shadowing bit 5: ??? (related to 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) bit 4: ??? bit 3: ???