Chapter 2 Hardware Installation 17
Independent IRQ Mode (JP1-JP4)In this mode, the IRQ level for each of the four ports is set individual-
ly. For each port, select an IRQ which is not already in use by another
card in the system. The correspondence of jumpers to ports is shown
below.
Port 1 àJP1
Port 2 àJP2
Port 3 àJP3
Port 4 àJP4
Shared IRQ Mode (JP1)Select an IRQ which is not already in use by another card in the
system. If you are installing more than one PCL-849, set them to
different IRQ numbers. Jumper Bank JP1 controls the shared card
IRQ. Simply place the jumper on the required interrupt level as
shown in the following figure.
Interrupt Status Register Setup (S1, Vectoraddress)This feature on the PCL-849 is utilized in the enhanced mode only.
When data arrives at one of the four ports, it will generate an interrupt
in the interrupt register. The PC software can read this, and identify
immediately which port generated the interrupt. This saves time, and
makes programming easier. In DOS or Windows 3.1, when a data bit
of the interrupt status register is set to 0, the corresponding channel is
selected to generate an interrupt. If the bit is 1, then no interrupt is
generated. In Windows 95/98/NT, when a data bit of the interrupt
status register is set to 1, the corresponding channel is selected to
generate an interrupt. If the bit is 0, then no interrupt is generated. DIP