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The CPU has a standard three bus input/output arrangement comprising the data bus, address bus and control bus.
Data Bus. D7 - DO D0 constitutes an 8-bit bi-directional data bus with active high, tri-state input/outputs. It is used during keyboard scanning, for exchanges with the gate array (in particular with the memory over the memory data bus MDH-MDA) and is available on the peripheral expansion connector PL8.
Address Bus. A15 - AO A0 constitutes a 16-bit address bus with active high tri-state outputs. It is used to set up addresses for the gate array (in particular with the memory on memory address bus MA19 - MA0), for keyboard scanning (A15 - A8 only) and is available on the peripheral expansion connectors PLO and PL9.
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