Card Setup
Sealevel Systems
PCIO
Page
4
IRQ Selection
Headers E4 and E5 select the interrupt request for each 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. If LPT1:
is selected IRQ7 should be used if LPT2: is selected IRQ5 should be
used.
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
.
Note:
The actual Silk-Screen for the
PCIO
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 at header E6, and setting the appropriate
selections at E3. Consult your particular software for IRQ selection. If no
interrupt is desired, remove the jumper.
Interrupt Modes
Jumper block E5 allows you to select a single interrupt per port mode or a
shared interrupt mode. The single interrupt per port mode is the typical
DOS, O/S 2 and Windows mode of operation.
The shared interrupt mode, which allows more than one port to access a
single IRQ, indicates the inclusion of a 1K ohm pull-down resistor
required on one port when sharing interrupts. This mode is used by
software that requires COM3: and COM4: to share interrupts with COM1:
and COM2: or in an OEM configuration to support a specific software
application.
Placing the jumper on ‘N’ selects the normal single interrupt per board
mode. Placing the jumper on the ‘M’ position selects the multi interrupt
mode. The multi interrupt mode allows you to share the IRQ signal(s) with
other cards that support multiple interrupts. The ‘M’ and ‘N’ selections
for the serial port are under ‘SP’ and labeled ‘PP’ for the parallel Port.
Summary of Contents for PCIO 4035
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