A. Jumper Configurations
114
W24-27
CPU Configuration - connects external hardware functions to multiplexed CPU pins.
The CPU multiplexes DMA channel 0 and DMA channel 1 with serial port COM2
signals. In short, if DMA channel 0 is used to support STD bus DMA (such as the
Ziatech ZT 8954 floppy disk controller), Data Carrier Detect and Clear To Send are not
available for COM2. If DMA channel 1 is used to support local DMA (such as the 1284
printer port), Transmit Data and Receive Data are not available for COM2. When W24
and W25 are configured for COM2 CTS and CDC, the BIOS setup option for COM2
must be "ONBOARD."
W24a
W24b
W25a
W25b
CPU Configuration
†
IN
OUT
IN
OUT
DMA channel 0
OUT
IN
OUT
IN
COM2 CTS and DCD
W26a
W26b
W27a
W27b
CPU Configuration
†
IN
OUT
IN
OUT
COM2 TXD and RXD
OUT
IN
OUT
IN
DMA channel 1
†
Factory default configuration for DOS systems.