User manual

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.