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External Interrupts in Challenge and Onyx Systems
The hardware architecture of the Challenge/Onyx series supports external interrupt signals as follows:
- Four jacks for outgoing signals are available on the master IO4 board. A user-level program can change the level of these lines individually.
- Two jacks for incoming interrupt signals are also provided. The input lines are combined with logical OR and presented as a single interrupt; a program cannot distinguish one input line from another.
The electrical interface to the external interrupt lines is documented at the end of the ei(7) reference page.
A program controls the outgoing signals by interacting with the external interrupt device driver. This driver is associated with the device special file /dev/ei, and is documented in the ei(7) reference page.
- Generating Outgoing Signals
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- Receiving Incoming External Interrupts
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