E x p a n s i o n C a r d s
LS/VS 550 OWNER’S HANDBOOK 4/5
DMA
Default assignment
Available?
DMA3
Enhanced Capabilities Port (default)
Optionally
DMA4
System
No
DMA5
16-bit Audio
Optionally
DMA6
Yes
DMA7
Yes
Base input/output (I/O) port address
I/O ports are used by the processor to communicate with hardware
devices. Some expansion cards are also controlled by I/O ports. The
base I/O port address specifies where the card’s ports begin. The
following table lists the I/O ports used by devices on the
motherboard. Any ports not listed below may be available for an
expansion card.
I/O ports
Default assignment
000h-01Fh
DMA controller 1
020h-021h
Interrupt controller 1
034h, 038h, 03Ch
Alternate Local bus ATA/IDE
040h-05Fh
System timer
060h-06Fh
Keyboard controller
070h-07Fh
Real-time clock, NMI mask
080h-09Fh
DMA page register
0A0h-0A1h
Interrupt controller 2
0B4h, 0B8h, 0BCh
Local bus ATA/IDE
0C0h-0DFh
DMA controller 2
0F0h, 0F1h
Math coprocessor busy (clear/reset)
0F8h-0FFh
Math coprocessor
1F0h-1F7h
Hard disk drive controller
200h-207h
Game I/O (disable)
220h-22Fh, 230h-233Fh
Sound blaster system