Port Enable / Disable; Irq Selection; Figure 3 - Header E6, Irq Selection - SeaLevel DUAL SIO 3082 User Manual

Port Enable / Disable

Each port on the Dual SIO can be enabled or disabled with switch position
8 on the DIP-switch. The port is enabled with the switch "On" or "Closed"
and disabled when "Off" or "Open". If any port is disabled, be sure to
disable the interrupt request for that port by removing the IRQ jumper.

IRQ Selection

Header E1 and E2 select the interrupt requests for each serial port. If
COM1: is selected, the corresponding jumper must be on the IRQ4
setting. If COM2: is selected, the corresponding jumper must be on IRQ3.
Note: Most communications software applications default COM3: to
IRQ4 and COM4: to IRQ3. This requires the sharing of interrupts
between COM1: and COM3:, and between COM2: and COM4:.
While this is the default, it is not always the preferred setting.
Check your software configuration instructions to determine the
most appropriate IRQ selection.
Figure 3 - Header E6, IRQ Selection (Factory Default)
Note: The actual Silk-Screen for the Dual SIO may have a "2" in place of
the IRQ "2/9" selection.
Any two or more ports can share a common IRQ by placing the jumpers
on the same IRQ setting if desired, due to a unique open collector/pull-up
IRQ drive circuit. Consult your particular software for IRQ selection. If
no interrupt is desired, remove the jumper.
Sealevel Systems Dual SIO
E1 E2
Card Setup
Page 3