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Configuring the PIO Module
The only jumpers on the PIO board are for interrupt daisy chain signals IEI and IEO. If
your system has more than one device using interrupt mode 2, it will be necessary
to set up an interrupt daisy chain.
This is fully described in the Z80 peripherals data sheet, but essentially it requires
linking the output (IEO) of one interrupt generating device to the input (IEI) of the
next, and so on. The position in the chain determines the device’s interrupt priority.
The illustration shows the connections required when using external Dupont wires
on P4 (shown in red) and the RC2014 bus USER pins (shown in yellow). To connect
the IEI and IEO signals to the RC2014 bus fit shunts to jumpers J1 and J2 (shown in
green).
Note that v1.0 of the PCB has the IEI and IEO bus pins incorrectly labelled. It
indicates the use of pins 37 and 38, not 38 and 39.
Setting up a mode 2 interrupt system is not trivial so requires study of the data
sheets rather than following any simple example I could write here.
