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(10 marks) Question 3: Given in Figure 2 the internal architecture of 8255A: Power Supplies +5V OND Group Group А Port А (8) VO PAPAD control Group A Port C Upper (444 Bidirectional daa bus VO PC7. PC4 Data bus buffer 07.00 8 bit internal data bus Group Port C Lower (4) PA31 40 b PA4 PA22 39 PAS PA173 38 PA6 PAO4 37 PAZ RD 5 36 WR d6 35 RESET GND7 34 DO A1 08 3301 Aogg 32D2 PC710 3103 PC611 8255A 30604 PC512 2905 PC413 2806 PCO 14 PC1015 26 Vcc PC216 25287 PC317 24286 PBO 18 23285 PB1 19 22PB4 PB2 20 21PB3 VO PC. PCO D7ם 27 Group RD WR A1 AD Read/ write Control Logic B control Group B Port VO PB7.PRO Reset 8) 18 Figure 2: Internal architecture of 8255A.

a) Find the control word to configure port in mode 2 and port B as output port in mode 1. [2] b) A control word is given CW=A7H. Explain the conditions of ports of 8255A. [2] c) If the 7th bit (PC7) of port C has to be "Reset", then what is the BSR control word? [2] d) Given the configuration in Figure 3 where 8255A interfaced with 8086 microprocessor where the pin CS is activated by binary address A7-A2= 111110. Find the port addresses for Port A Port B, Port C and Control Word register. [2] PAT 1 PAD Ver ku ke Buffer AT A AS 14- AL PC7 T Buffer PC4 Kw 8255A AL A mi the RD PO PRZ WR RESET PRO DIP Switch Al AO SELECTION 0 PORTA . 1 FORI 8 1 0 PORT Ở 0 CONTROL Em 3 M w Figure 3.8255A Interfaced with microprocessor