2) The following questions are set up in view of the figures (a,b).

a) Describe what type of I/0 operation is carried out in Figure (a). Write an instruction

sequence that will input the byte contents of input port 6 to memory location MEMI.

b) What is the polling operation? Write a sequence of instructions to poll the input I7 at

input port 5 to check whether it is switched to zero or not. Figure (a).

c) Write a sequence of instructions that will read the contents of input port 7. Mask off all

the bits except LSB. The content of LSB will be shifted to CF. If CF =1, then the program

will go to start of service routine XXX. Figure (a).

d) Describe what type of I/O operation is carried out in Figure (b). Write a sequence of

instructions to initialize the control register in PPI O in Figure (b) so that PA is an output

port, PB and Pc are input ports. Initialize all the necessary registers. Ports are configured for

mode 0 operation

e) Write a program to input the contents of Pp and Pc then OR them together and send

the resultant to PA. These ports are the PPI O ports in Figure (b). Ports are configured for

mode 0 ope tion. Initialize all the necessary registers.

Write comments and Use minimum number of instructions in your programs.

ALI OR CHA ALAD Figure (a) Control bus Address bus A A Data bus , > B A A A IO/M 74F138 G GA To other even address periphera 11 O CS Port A D D 1o-D; A 8255A Port C A RD RD WR Port B WR Figure 7.27 Memory-mapped 8255A 10 ports in an 8088 microcomputer Figure (b) ALI OR CHA ALAD Figure (a) Control bus Address bus A A Data bus , > B A A A IO/M 74F138 G GA To other even address periphera 11 O CS Port A D D 1o-D; A 8255A Port C A RD RD WR Port B WR Figure 7.27 Memory-mapped 8255A 10 ports in an 8088 microcomputer Figure (b)