1. Data and addressing

Registers on this chip are addressed by the microprocessor as part of its overall RAM-ROM memory space. The attached table of read-write addresses summarizes the addressable functions. There are no registers that are both read and write. Some addresses however are both read and write, with write data going into one register and read data returning from a different register.

If the read-write line is low, the data bits indicated in this table will be written into the addressed write location when the 02 clock goes from high to low. Some registers are eight bits wide, some only one bit, and some (strobes) have no bits, performing only control functions (such as resets) when their address is written.

If the read-write line is high, the addressed location can be read by the microprocessor on data lines 6 and 7 while the 02 clock is high.

The addresses given in the table refer only to the six (6) real address lines. If any of the four (4) chip select lines are used for addressing, the addresses must be modified accordingly.

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