(SEM V) THEORY EXAMINATION 2017-18 MICROPROCESSOR

Microprocessor (NEC-503)

Section-Wise Important Questions & Study Notes

SECTION–A

(Attempt all questions | 2 × 10 = 20)
 This section checks basic concepts, definitions, and short explanations.
Write 2–3 lines only, be precise.

1. Microprocessor & Technology Used

A microprocessor is a programmable digital device that performs arithmetic, logic, and control operations.
It is fabricated using VLSI (Very Large Scale Integration) technology.

2. Buses in a Microprocessor

Address bus: carries memory addresses                      Data bus: transfers data

Control bus: carries control signals like RD, WR, ALE

3. Basic Block Diagram of Microprocessor

Includes ALU, registers, control unit, buses, and clock system.
Explain function of each block briefly.

4. Address Capability of 8085 (64 KB)

8085 has a 16-bit address bus, so it can access

216=65,536 bytes =64 KB2^{16} = 65,536 \text{ bytes } = 64 \text{ KB}216=65,536 bytes =64 KB 

5. Instruction Set of 8085

8085 supports 74 basic instructions (around 246 opcodes including variations).

6. Addressing Modes of 8085

Immediate, Register, Direct, Register Indirect, and Implied addressing modes.

7. Memory Segmentation in 8086

Memory is divided into segments (CS, DS, SS, ES) of 64 KB each to access 1 MB memory efficiently.

8. Hardware Interrupts in 8085

8085 supports 5 hardware interrupts:            TRAP, RST 7.5, RST 6.5, RST 5.5, INTR.

9. I/O Ports in 8085

8085 can access 256 I/O ports using 8-bit port addressing.

10. Multiplexing of A0–A7 and D0–D7

To reduce pin count, lower address bus and data bus are multiplexed and separated using ALE signal.

SECTION–B

(Attempt any THREE | 10 × 3 = 30)
Answers should be descriptive and supported with neat diagrams.

1. Architecture of 8085

Draw and explain:                                 ALU

Accumulator                                         Registers

Instruction decoder                              Timing & control unit

2. Interrupts in 8085

Explain:                                                 Hardware interrupts

Software interrupts                               Priority order

Masking of interrupts

3. IC-8254 Timer

Draw pin diagram & block diagram.
Explain counters, control word register, and modes of operation.

4. I/O Mapped I/O vs Memory Mapped I/O

5. Programmable Peripheral Interface (8255)

Explain block diagram and Modes 0, 1, and 2 with applications.

SECTION–C

(Attempt any ONE | 10 × 1 = 10)

3(a) 8086 Architecture                               Explain features and draw block diagram.
Explain functions of:

BIU (Bus Interface Unit)                          EU (Execution Unit)

OR

3(b) Interrupts in 8086

Explain:                                                      Hardware interrupts

Software interrupts                                    NMI and maskable interrupts