PORTIBM PC Portable (uses same BIOS as XT) 0464-0465 - EISA(Enhanced Industry-Standard Architecture) A 32-bit superset of the IBMInternational Busiuness Machines ATIBM PC AT's expansion bus (which is now known as the ISA or Industry-Standard Architecture bus). BUS MASTER STATUS

0464w R	  bus master status latch register (slots 1-16)
	identifies the last bus master that had control of the bus (bit N =0 if
	  slot N+1 had control last)