HP X Class 500/550MHz, Reference Manual

Page: 106 / 149

106 Chapter 4
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.
0778 - 077B LPT1 ECP
0CF8 - 0CFF PCI configuration space
8000 - PIIX4E Power Management I/O Space
8400 - NS317 ACPI Registers
8800 - PIIX4E SMBus I/O Space
Table 4-5. Summary Of How The DMA Channels Are Allocated
DMA controller
Channel Function
DMA 0 AD1816 Capture
DMA 1 AD1816 Playback
DMA 2 NS317 Flexible disk controller
DMA 3 NS317 LPT ECP
DMA 4 Used to cascade DMA channels 0-3
DMA 5 Free
DMA 6 Free
DMA 7 Free
Table 4-4. HP I/O Port Map
Default Values for
I/O Address Ports Function