2) The following questions are set up in view of the figures (a,b). a) Describe what type of I/O 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 17 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 10 operation is carried out in Figure (b). Write a sequence of instructions to initialize the control register in PPI 0 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 PB 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 operation. Initialize all the necessary registers. Write comments and Use minimum number of instructions in your programs. ALE 356 CLK Au Am AD, ADA A 74F373 23 Address Latch OE An Au CBA dG 74F138 G. Input 74F244 Porto A 10/M SORS MPU output Gaddress decoder G A AD, AD D, D, 74F245 Data bus transceiver DT/R DIR 74F244 Port 1 DEN G RD 74F244 Port 7 Figure (a) Figure 7.12 Sixty-four-line input circuit for an 8088 microcomputer Control bus Address bus A - Ag Data bus Do-D op Az A A B As 74F138 Ao 12 GB To other even address peripheral 10 10/M L+ [ - 6 2 8 GA 1 Ai G 0. CS Port A D-D7 Do-D A 8255A Port C A2 A RD RD WR Port B WR Figure 7.27 Memory-mapped 8255 A 10 ports in an 8088 microcomputer, Figure (b) 2) The following questions are set up in view of the figures (a,b). a) Describe what type of I/O 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 17 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 10 operation is carried out in Figure (b). Write a sequence of instructions to initialize the control register in PPI 0 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 PB 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 operation. Initialize all the necessary registers. Write comments and Use minimum number of instructions in your programs. ALE 356 CLK Au Am AD, ADA A 74F373 23 Address Latch OE An Au CBA dG 74F138 G. Input 74F244 Porto A 10/M SORS MPU output Gaddress decoder G A AD, AD D, D, 74F245 Data bus transceiver DT/R DIR 74F244 Port 1 DEN G RD 74F244 Port 7 Figure (a) Figure 7.12 Sixty-four-line input circuit for an 8088 microcomputer Control bus Address bus A - Ag Data bus Do-D op Az A A B As 74F138 Ao 12 GB To other even address peripheral 10 10/M L+ [ - 6 2 8 GA 1 Ai G 0. CS Port A D-D7 Do-D A 8255A Port C A2 A RD RD WR Port B WR Figure 7.27 Memory-mapped 8255 A 10 ports in an 8088 microcomputer, Figure (b)
