Description:The contents of the HL register pair are placed on the address bus to select a
location in memory. The byte contained in this memory location is
temporarily stored in the CPU. Then, after the byte counter (B) is
decremented, the contents of register C are placed on the bottom half (A0
through A7) of the address bus to select the I/O device at one of 256
possible ports. Register B may be used as a byte counter, and its
decremented value is placed on the top half (A8 through A15) of the
address bus. The byte to be output is placed on the data bus and written to a
selected peripheral device. Finally, the register pair HL is incremented.
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