250+ TOP MCQs on Microprocessor of Embedded System and Answers

Embedded Systems Multiple Choice Questions on “Microprocessor of Embedded System”.

1. Which of the following microprocessor is designed by Zilog?
A. Z80
B. Zigbee
C. 80386
D. 8087
Answer: A
Clarification: Designed by Zilog in 1976. 80386 and 8087 are the processors designed by Intel and Zigbee is IEEE based which is used for high-level communication protocol.

2. Z80 is mainly based on
A. Intel 8080
B. MIPS
C. TIMS
D. 8051
Answer: A
Clarification: Its architecture is based on Intel 8080 but has an extended instruction set and hardware improvement.

3. Flag register of Z80 is also known as
A. Program status register
B. Program status address
C. Program status word
D. Program address register
Answer: C
Clarification: The flag register of Z80 contains status information such as carry, overflow, signed etc.

4. What are the two register sets used in Z80?
A. C’D’ and BC’
B. CD and BD
C. IV and MR
D. Main and alternate
Answer: D
Clarification: Z80 have two sets of registers which are the main registers and alternate registers.

5. How an alternate set of the register can be identified in Z80?
A. ‘Suffix
B. ‘Prefix
C. ,suffix
D. ,prefix
Answer: A
Clarification: In order to identify the main register and alternate register ‘ is used in the suffix.

6. What is the purpose of memory refresh register of Z80?
A. To control on-chip DRAM
B. To control on-chip SRAM
C. To control ROM
D. To clear cache
Answer: A
Clarification: In addition to the general purpose registers, a stack pointer, program counter, and two index registers are included in Z80. It was also used in many embedded designs because of its high-quality performance and for its in-built refresh circuitry for DRAMs.

7. What is the clock frequency of Z80?
A. 6 MHz
B. 8 MHz
C. 4 MHz
D. 2 MHz
Answer: C
Clarification: It is the maximum clock frequency or runs a time of the processor.

8. Which are the two additional registers of Z80?
A. Interrupt and NMI
B. NMI and PSW
C. Interrupt vector and memory refresh
D. NMI and memory refresh
Answer: C
Clarification: The Interrupt vector(IV) register is used in the interrupt handling. Mode 2 is used to point the required software routine to process the interrupt. In mode 1, the interrupt vector is supplied via the external data bus.

9. By which instruction does the switching of registers take place?
A. Instruction opcodes
B. AXX instruction
C. EXX instruction
D. Register instruction
Answer: C
Clarification: Only one set of registers can be used at one time and the switching of registers and data transfer is performed by the EXX instruction.

10. Which of the following can be a paired set of 16-bit register?
A. CD
B. HL
C. AB
D. EH
Answer: B
Clarification: Registers B, C, D, E, H and L are 8-bit general-purpose registers that can be concatenated to produce 16 registers known as BC, DE, and HL.

11. Which signal is used to differentiates the access from a normal memory cycle?
A. HALT
B. RESET
C. MREQ
D. IORQ
Answer: D
Clarification: The IORQ signal is used to differentiate the access from a normal memory cycle. These input/output accesses are similar from a hardware perspective to a memory cycle but only occur when an input/output port instruction is executed.

12. What is done in mode1 of Z80?
A. Interrupt vector is supplied via the external bus
B. Interrupt vector is supplied via the peripherals
C. NMI gets started
D. Interrupt gets acknowledge from peripheral
Answer: A
Clarification: In mode 1, the interrupt vector is supplied via the external data bus. The memory refresh register is used to control the on-chip DRAM refresh circuitry.

13. What does m1 signal in Z80 describes?
A. I/O operation status
B. Memory refresh output
C. Output pulse on instruction fetch cycle
D. Interrupt request input
Answer: C
Clarification: It is a signal which describes output pulse on the instruction fetch cycle. Interrupt request input, input/output operation status, memory refresh output are the other signals in Z80 for various operations.