Specifications

158004.B00 47
Ethernet controllers and to PCI boards. The Advanced / Audio Options menu allows
the SoundBlaster audio sub-system to be disabled, or its interrupt to be changed.
4.6 DMA
The Geode GX1 processor contains the same DMA controller circuit as is present on
all PC computers. This consists of two 8237 type interrupt circuits, each with four
DMA Request (DREQ) inputs and four DMA acknowledge (DACK) outputs. One 8237
is connected in cascade with the other, leaving seven DMA channels available.
DMA channels 0, 1, 2 and 3 can be used for 8-bit DMA transfers, and DMA channels
5, 6 and 7 can be used for 16-bit DMA transfers.
One pair of DMA pins (DRQ2 and /DACK2) is connected to the on-board floppy disk
controller, as well as to DRQ2 and /DACK2 pins on the PC/104 bus. If the floppy disk
controller is disabled then these pins can be used for DMA devices on the PC/104
bus.
The SoundBlaster-compatible audio circuitry within the Geode GX1 chip set also
requires DMA channels. These may be set up using the BIOS Setup program.
The PC/104-Plus bus (PCI bus) has no DMA signals.