PlacementPrepThe 8085 microprocessor has a data bus of width:
Solution
The 8085 is an 8-bit processor with a 16-bit address bus.
Answer: (D) 8 bits
Technical · Electronics and Communication (ECE)
Microprocessors and Microcontrollers MCQs for placement tests
20 technical questions of moderate difficulty, as asked in campus placement and company tests. Each has a short explanation.
The 8085 address bus is 16 bits wide, so it can address:
Solution
2¹⁶ = 65,536 locations = 64 KB.
Answer: (B) 64 KB of memory
The 8086 microprocessor can address how much memory?
Solution
It has a 20-bit address bus: 2²⁰ = 1 MB.
Answer: (A) 1 MB
Which 8085 interrupt has the highest priority and is non-maskable?
Solution
TRAP is non-maskable and has the highest priority.
Answer: (A) TRAP
Which register in the 8085 holds the address of the next instruction?
Solution
The program counter points to the next instruction to fetch.
Answer: (D) Program counter
The stack in the 8085 grows:
Solution
PUSH decrements the stack pointer.
Answer: (C) Downwards (towards lower addresses)
Which flag is set when the result of an operation is zero?
Solution
The Z flag is set to 1 when the result is 0.
Answer: (C) Zero flag
In the 8086, the physical address is calculated as:
Solution
The 16-bit segment is shifted left by 4 bits and the offset added.
Answer: (C) Segment × 16 + Offset
What is the physical address for segment 2000H and offset 0050H in the 8086?
Solution
2000H × 10H + 0050H = 20000H + 0050H = 20050H.
Answer: (B) 20050H
Which addressing mode is used in MVI A, 32H?
Solution
The data 32H is part of the instruction.
Answer: (A) Immediate addressing
A microcontroller differs from a microprocessor because it:
Solution
A microcontroller integrates CPU, memory and peripherals.
Answer: (A) Has memory and I/O ports on the same chip
The 8051 microcontroller has how many 8-bit I/O ports?
Solution
Ports P0, P1, P2 and P3.
Answer: (C) 4
How much internal RAM does the basic 8051 have?
Solution
The 8051 has 128 bytes of internal RAM and 4 KB of on-chip ROM.
Answer: (B) 128 bytes
DMA is used to:
Solution
Direct Memory Access frees the CPU during bulk transfers.
Answer: (D) Transfer data between memory and I/O without the CPU
The 8255 is a:
Solution
The 8255 PPI provides programmable I/O ports.
Answer: (C) Programmable peripheral interface
The 8259 is a:
Solution
It manages up to eight interrupt sources and can be cascaded.
Answer: (D) Programmable interrupt controller
Which instruction in the 8085 complements the accumulator?
Solution
CMA complements every bit of the accumulator; CMC complements the carry flag.
Answer: (C) CMA
RISC processors typically have:
Solution
RISC uses simple, fixed-length instructions for fast pipelining.
Answer: (A) A small set of simple instructions
In memory-mapped I/O, I/O devices are accessed using:
Solution
Devices share the memory address space.
Answer: (B) Memory instructions and addresses
The 8085 instruction ADD B adds register B to:
Solution
Arithmetic results are stored in the accumulator.
Answer: (D) The accumulator
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