# Switch 2/4: bus master DMA enable/disable

The position of switch 2/4 has no effect if the Ringnode is installed in an 8-bit slot or if switch 2/5 is OFF. Bus master DMA is not possible in these circumstances.

Switch 2/4 | Bus master DMA
ON (Default) | Enabled
OFF | Disabled

You must use 16-bit mode if you are installing the Ringnode in a Novell NetWare 4.x or 3.x server. The following table summarizes the types of data transfer associated with different combinations of switches 2/4 and 2/5, and with the Ringnode in an 8- or 16-bit expansion slot:

Switch settings | 8-bit slot | 8-bit slot | 16-bit slot | 16-bit slot
Switch 2/4 setting | ON | OFF | ON | OFF
Switch 2/5 ON | c | c | a | b
Switch 2/5 OFF | c | c | c | c

Types of data transfer associated with different settings of switches 2/4 and 2/5

a | = | 16-bit bus master DMA
b | = | 16-bit I/O transfer
c | = | 8-bit I/O transfer