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Hardware
As I said up above, the hardware started to seriously take shape when I was given an Amiga 600 for free. As I already had an A1200, the A600 wasn't of any other use, but ideal as a donor machine. What I needed from the hardware was:
- Relay outputs, so the system could control mains powered equipment, e.g. lights & lamps, stereos etc.
- Infra-red remote reception via InfraRexx hardware, which required one line of the joystick port as an input.
- Alphanumeric output for status monitoring, clock functions etc.
- Audio output for status / alarms.
- A number of logic inputs for sensors and manual pushbuttons.
- A serial link for remote controlling the system.
I had originally intended to include voice commands using the rather good VoiceShell and a parallel port sampler using the 8-bit ZN448 ADC IC. However, This didn't give very satisfactory results given the demands placed on the 7MHz, 2MB machine. It did work, but made the entire system slow to a crawl, so it was ditched and the parallel port used instead for the alphanumeric LCD. The joystick port is used by InfraRexx - unfortunately the other lines on that port are tied up by the software even when they're not used so the lines on the mouse port were used as logic inputs for pushbuttons and sensors. The serial port ws used for a null modem link to my A1200, allowing remote control of the system and sending & receiving of files.
Given that the joystick, mouse, parallel and serial ports were all used up, it left very little in the way of outputs for the relay controllers. So, as the machine was going to be used exclusively with a hard drive, I decided to use the floppy drive control lines as my outputs. They're off the CIAs, and as I was writing the driving software myself, it made almost no difference whether the outputs were on the joystick ports, parallel port or floppy port - at the end of the day I was poking CIA addresses and getting my outputs somewhere. Five of the control lines were routed to transistors, which in turn switched on or off five relays. A 25-way ribbon cable was run around the room with D-type connectors at various intervals, allowing the connection of different modules. The alphanumeric display was one, for example, pushbutton controls another and a PIR sensor another again. All the required signals were simply connected directly to their required ports or the power supply. Yes, this is somewhat risky given the long lengths and unisolated & unbuffered nature of the system, but it worked for me for years without a single issue.
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