In the Oric, the PORT-A is used to control the printer and the soundchip, PORT-B is used to scan the keyboard, check the printer status and control the relay switch.The MCS6522 Versatile Interface Adapter (VIA) provides all of the capability of the MCS6520. In addition, this device contains a pair of very powerful interval timers, a serial-to-parallel/parallel-to-serial shift register and input data latching on the peripheral ports. Expanded handshaking capability allows control of bi-directional data transfers between VIA's in multiple processor systems.
Control of peripheral devices is handled primarily through two 8-bit bi-directional ports. Each of these lines can be programmed to act as either an input or an output. Also, several peripheral I/O lines can be controlled directly from the interval timers for generating programmable-frequency square waves and for counting externally generated pulses. To facilitate control of the many powerful features of this chip, the internal registers have been organized into an interrupt flag register, an interrupt enable register and a pair of function control registers.
Without any additional circuitry, is it possible to use any of these to communicate between the various machines, like for example using the printer port or the keyboard?
Basically, on the master machine, all we really care is the keyboard, sound generator and expansion bus, we don't care about the printer.
On the slave machines, we don't care about the printer, and we don't need the keyboard either, and the expansion bus is probably no necessary either (except maybe to plug something like a speech synthesizer ).
I wish I was as comfortable with hardware as I am with software... but unfortunately not!