How many I/O interface units of the type shown in Figure 11-6 can be addressed by using a 16-bit address, assuming

(a) Each of the chip select (CS) lines is attached to a different address line?

(b) Address bits are fully decoded to form the chip select inputs?

Figure 11-6

Transcribed Image Text:

Bidirectional data bus Chip select Register select I/O read I/O write To CPU CS 0 1 1 1 1 Bus buffers CS R$1 RSO Timing and control RD WR RS1 X 0 0 1 1 RS0 X 0 1 0 1 Internal bus Port A register Control register Status register Port B register Control register Status register Register selected None: data bus in high-impedance state Port A register Port B register I/O data I/O data Control lines Status lines To I/O device