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5 HP BIOS
BIOS Addresses
DMA Channel Controllers
Only “I/O-to-memory” and “memory-to-I/O” transfers are allowed.
“I/O-to-I/O” and “memory-to-memory” transfers are disallowed by the
hardware configuration.
The system controller supports seven DMA channels, each with a page
register used to extend the addressing range of the channel to 16 MB.
The following table summarizes how the DMA channels are allocated.
Interrupt Controllers
The system has an Interrupt controller which is equivalent in function to
that of two 82C59 interrupt controllers. The following table shows how the
interrupts are connected to the APIC controller. The Interrupt Requests
(IRQ) are numbered sequentially, starting with the master controller, and
followed by the slave (both of 82C59 type).
03F8 - 03FF COM1
04D0 - 04D1 Interrupt edge/level control
0778 - 077F LPT1 ECP
0CF8 - 0CFF PCI configuration space
C000 - Power Management I/O space and ACPI Registers
C100 - SMBus I/O space
Default Values for
I/O Address Ports
Function
DMA controller
Channel Function
DMA 0 Free
DMA 1 Free if not used for parallel port in Setup
DMA 2 Floppy disk drive controller
DMA 3 Free if not used for parallel port in Setup
DMA 4 Used to cascade DMA channels 0-3
DMA 5 Free
DMA 6 Free
DMA 7 Free