The addresses assigned to the four registers of the I/O interface of Fig. 11-2 are equal to the binary equivalent of 12, 13, 14, and 15. Show the external circuit that must be connected between an 8-bit I/O address from the CPU and the CS, RS1, and RS0 inputs of the interface.

Fig. 11-2

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Bidirectional data bus Chip select Register select 1/0 read 1/0 write CS RS1 RSO Timing and control RD Bus buffers WR To CPU 1 1 CS RS1 RSO Register selected 0 1 X X 0 0 1 I 0 1 0 Internal bus 1 Port A register Port B register Control register Status register To 1/0 device None: data bus in high-impedance Port A register Port B register Control register Status register I/O data I/O data Control Status