PORTIBM PC Portable (uses same BIOS as XT) 0048-004B - 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). - PROGRAMMABLE INTERVAL TIMER 2
Note:	this second timer is also supported by many Intel chipsets
SeeAlso: PORTIBM PC Portable (uses same BIOS as XT) 0040h,PORTIBM PC Portable (uses same BIOS as XT) 0044h

0048  RW  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). PIT2 counter 3 (Watchdog Timer)
0049  ??  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). 8254 timer 2, not used (counter 4)
004A  RW  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). PIT2 counter 5 (CPU(Central Processing Unit) The microprocessor which executes programs on your computer. speed control)
004B  -W  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). PIT2 control word