MICROPROCESSOR
2 marks questions and answers
UNIT-I
1. Define microprocessors?
A semiconductor device(integrated circuit) manufactured by using the LSI
technique. It includes the ALU, register arrays, and control circuits on a single
chip.
2. Define microcomputer?
A computer that is designed using a microprocessor as its CPU. It includes
microprocessor, memory and I/O.
3. Define ROM?
A memory that stores binary information permanently. The information can
be read from this memory but cannot be altered.
4. What is an ALU?
The group of circuit that provides timing and signals to all operation in the
computer and controls data flow.
5. What is Micro controller?
A device that includes microprocessor, memory, and I/O signal lines on a
single chip, fabricated using VSLI technology.
6. What is an Assembler?
A computer program that translate an assembly language program from
mnemonics to the binary machine code of a computer.
7. What are the four primary operations of a MPU?
, 1. Memory read
2. Memory write
3. I/O read
4. I/O write
8. What do you mean by address bus?
A group of lines that are used to send a memory address or a device address
from the MPU to the memory location or a peripheral. The 8085 microprocessor
has 16 address lines.
9. How many memory locations can be addressed by a microprocessor with 14
address lines?
The 8085 MPU with its 14-bit address is capable of addressing 214=16,384
(ie) 16K memory locations.
10. Why is the data bus bi-directional?
The data bus is bi-directional because the data flow in both directions
between the MPU and memory and peripheral devices.
11. What is the function of the accumulator?
The accumulator is the register used to store the 8-bit data to perform the
arithmetic and logical operations.
12. Define control bus?
This is single line that is generated by the MPU to provide timing of various
operations.
13. What is a flag?
The data conditions, after arithmetic or logical operations, are indicated by
setting or resetting the flip-flops called flags.
, 14. Why are the program counter and the stack pointer 16-bit registers?
Memory locations for the program counter and stack pointer have 16-dit
address. So the PC and SP have 16-bit registers.
15. Define memory word?
The number of bits stored in a register is called a memory word.
16. Specify the number of registers and memory cells required in a 128 x 4
memory chip?
Number of registers=128
Memory cells required is 128 x 4=512
17. Explain the function of ALU and IO/M signals in the 8085 architecture?
The ALU signal goes high at the beginning of each machine cycle indicating
the availability of the address on the address bus, and the signal is used to latch the
low-order address bus. The IO/M signal is a status signal indicating whether the
machine cycle is I/O or memory operation. The IO/M signal is combined with the
RD and WR control signals to generate IOR, IOW, MEMW, MEMR.
18. If the 8085 adds 87H and 79H, specify the contents of the accumulator and the
status of the S, Z, and CY flag?
The sum of 87H and 79H=100H. Therefore, the accumulator will have 00H,
and the flags will be S=0, Z=1, CY=1.
19. Write down the control and status signals?
Two control signals and three status signals
Control signals: RD and WR
Status signals: IO/M, S1, S2
20. Define machine cycle?
Machine cycle is defined, as the time required completing one operation of
accessing memory, I/O, or acknowledging an external request.
2 marks questions and answers
UNIT-I
1. Define microprocessors?
A semiconductor device(integrated circuit) manufactured by using the LSI
technique. It includes the ALU, register arrays, and control circuits on a single
chip.
2. Define microcomputer?
A computer that is designed using a microprocessor as its CPU. It includes
microprocessor, memory and I/O.
3. Define ROM?
A memory that stores binary information permanently. The information can
be read from this memory but cannot be altered.
4. What is an ALU?
The group of circuit that provides timing and signals to all operation in the
computer and controls data flow.
5. What is Micro controller?
A device that includes microprocessor, memory, and I/O signal lines on a
single chip, fabricated using VSLI technology.
6. What is an Assembler?
A computer program that translate an assembly language program from
mnemonics to the binary machine code of a computer.
7. What are the four primary operations of a MPU?
, 1. Memory read
2. Memory write
3. I/O read
4. I/O write
8. What do you mean by address bus?
A group of lines that are used to send a memory address or a device address
from the MPU to the memory location or a peripheral. The 8085 microprocessor
has 16 address lines.
9. How many memory locations can be addressed by a microprocessor with 14
address lines?
The 8085 MPU with its 14-bit address is capable of addressing 214=16,384
(ie) 16K memory locations.
10. Why is the data bus bi-directional?
The data bus is bi-directional because the data flow in both directions
between the MPU and memory and peripheral devices.
11. What is the function of the accumulator?
The accumulator is the register used to store the 8-bit data to perform the
arithmetic and logical operations.
12. Define control bus?
This is single line that is generated by the MPU to provide timing of various
operations.
13. What is a flag?
The data conditions, after arithmetic or logical operations, are indicated by
setting or resetting the flip-flops called flags.
, 14. Why are the program counter and the stack pointer 16-bit registers?
Memory locations for the program counter and stack pointer have 16-dit
address. So the PC and SP have 16-bit registers.
15. Define memory word?
The number of bits stored in a register is called a memory word.
16. Specify the number of registers and memory cells required in a 128 x 4
memory chip?
Number of registers=128
Memory cells required is 128 x 4=512
17. Explain the function of ALU and IO/M signals in the 8085 architecture?
The ALU signal goes high at the beginning of each machine cycle indicating
the availability of the address on the address bus, and the signal is used to latch the
low-order address bus. The IO/M signal is a status signal indicating whether the
machine cycle is I/O or memory operation. The IO/M signal is combined with the
RD and WR control signals to generate IOR, IOW, MEMW, MEMR.
18. If the 8085 adds 87H and 79H, specify the contents of the accumulator and the
status of the S, Z, and CY flag?
The sum of 87H and 79H=100H. Therefore, the accumulator will have 00H,
and the flags will be S=0, Z=1, CY=1.
19. Write down the control and status signals?
Two control signals and three status signals
Control signals: RD and WR
Status signals: IO/M, S1, S2
20. Define machine cycle?
Machine cycle is defined, as the time required completing one operation of
accessing memory, I/O, or acknowledging an external request.
