Microprocessor — DU B. Sc. (Hons) Electronics Previous Year Question Papers

Instruction for Candidates a. Define the term 'multiplexed address/data bus' in 8085. Why is demultiplexing b. What is the role of Program Counter? Explain its operations in 8085 with an c. What are vectored and non-vectored interrupts of 8085? 3 d. How many counters does the 8253/8254 have, and what is their size? 3 f. Differentiate between memory mapped I/O and peripheral mapped I/O. 3 a. Name the various control and status signals in 8085. Explain their function. 6 b. Explain the function of (i) HOLD (ii) READY (iii) RESET OUT and (iv) SID. 6 c. Draw a schematic to interface a 4KB memory with 8085 if the starting address is A000H using decoder. Specify its memory map. a. Classify the instruction set of 8085 into different categories. Give one example of each category with their mnemonics and operation. b. Trace the execution of the following program. Show the content of involved registers and flags after each instruction: a. For the given figure, find the Port addresses of control register and counter 2. Is this a linear or absolute decoding? Write a subroutine to initialize counter 2 in Mode 0 with count of 50,00010. b. Describe the operating modes of 8255 PPI. What is the significance of the control word register? Draw the internal block diagram of 8255. c. Compare 8085 and 8086 microprocessors with respect to: data bus width, address bus width, internal architecture and number of registers. a. What are hardware and software interrupts? Calculate the vector address of b. Write an 8085 subroutine DELAY to generate a delay of 500 µs at 2MHz. 6 c. Explain SIM and RIM instructions. What is their role? Set the mask to enable RST 6.5 without modifying the mask of RST 5.5. and RST 7.5. a. Draw the complete timing diagram for the instruction LDA 3000H showing all machine cycles. c. Describe in relation to the 8259 Priority Interrupt Controller (i) Interrupt Request Register (IRR) (ii) In-Service Register (ISR) (iii) Fully nested mode a. What are the three categories in which operations of the 8085 microprocessor can be classified? Discuss any one of them. CALL and RET with a memory diagram. c. Explain the data transfer instructions of 8085: MOV, MVI, LDA and LHLD with syntax, operation, and example. Classify them based on their byte count. Control Word Format of 8255 MODE FOR - A PORT A PORT MODE - PORT - PORT CL Control Word Format of 8254