Quatech DS-200, Руководство пользователя

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6.1 Interrupt Sharing
Both ports on the DS-200/300 can share the same interrupt level or they
can share their interrupt with another Quatech adapter supporting
sharable interrupts. Jumper J2 can be used to connect the UART
generated interrupt directly to the selected IRQ or to enable the interrupt
sharing circuit. In either case, the software driving the serial ports must
determine which port or ports are requesting service when an interrupt is
generated. To maintain 100% ISA bus compatibility, J2 should be set in
the non-sharable mode.
J2 --- Sharable interrupt
1
1
4
4
2
2
5
5
3
3
6
6
1
4
4
1
2
5
5
2
3
6
6
3
Serial 0 non-sharable
Serial 1 non-sharable Serial 0 non-sharable
Serial 1 sharable
Serial 0 sharable
Serial 1 non-sharable
Serial 0 sharable
Serial 1 sharable
jumper block configurations
Figure 13--- Sharable interrupt selection
The DS-200/300 signals a hardware interrupt when any port requires
service. The interrupt signal is maintained until no port requires service.
Because the ISA bus is edge-sensitive, this behavior forces the interrupt
service routine to ensure that all ports are checked before exiting. A way
to do this is to poll each port until an interrupting port is found. After
servicing the port, all ports should be checked again. If any interrupting
port is left unserviced the DS-200/300 will be unable to signal any further
interrupts.
6-2 Quatech Inc.