This block diagram was our starting point from which we leapt with abandon into the glorious world of digital design. Main features to note are the four bit wide data bus, which is in no way connected to the controller. All devices on the bus are TRI_STATE®, and are run by the controller. One notable omission from the diagram are the clock connections. Obviously, most blocks will have the system clock connected, but there is a slower 8kHz clock for digitizing which is connected to the A/D and D/A blocks, as well as a controller input.
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