2 Marks Answer
1. What are the two design approaches of a control unit?
Ans: The two design approaches of a control unit are:
a. Hardwired Control Unit
b. Microprogrammed Control Unit
2. Name the stages of the instruction execution cycle and the registers involved in it.
Ans: The stages of the instruction execution cycle are:
a. Fetch
b. Decode
c. Execute
d. Memory Access
The registers involved are:
Program Counter (PC), Instruction Register (IR), Memory Address Register (MAR),
Memory Buffer Register (MBR), and Accumulator (ACC).
3. What are addressing modes? What are the types.
Ans: Addressing modes define how the operand of an instruction is chosen.
Types include:
a. Immediate Addressing
b. Direct Addressing
c. Indirect Addressing
d. Register Addressing
e. Indexed Addressing
f. Relative Addressing
4. What is a ripple carry adder?
Ans: A ripple carry adder is a binary adder where the carry output from each full adder
is passed to the next. The ripples carry through the circuit, causing delay as each bit is
added in sequence.
5. What is direct memory access?
Ans: Direct Memory Access (DMA) allows peripherals to access the main memory
directly without involving the CPU, enabling high-speed data transfer.
6. What are privileged instructions?
Ans: Privileged instructions are processor commands that can only be executed in
supervisor or kernel mode to protect system stability and security.
7. What is pipelining?
Ans: Pipelining is a technique used in CPUs where multiple instruction phases are
overlapped to improve performance. It allows the next instruction to begin before the
previous one finishes.
1. What are the two design approaches of a control unit?
Ans: The two design approaches of a control unit are:
a. Hardwired Control Unit
b. Microprogrammed Control Unit
2. Name the stages of the instruction execution cycle and the registers involved in it.
Ans: The stages of the instruction execution cycle are:
a. Fetch
b. Decode
c. Execute
d. Memory Access
The registers involved are:
Program Counter (PC), Instruction Register (IR), Memory Address Register (MAR),
Memory Buffer Register (MBR), and Accumulator (ACC).
3. What are addressing modes? What are the types.
Ans: Addressing modes define how the operand of an instruction is chosen.
Types include:
a. Immediate Addressing
b. Direct Addressing
c. Indirect Addressing
d. Register Addressing
e. Indexed Addressing
f. Relative Addressing
4. What is a ripple carry adder?
Ans: A ripple carry adder is a binary adder where the carry output from each full adder
is passed to the next. The ripples carry through the circuit, causing delay as each bit is
added in sequence.
5. What is direct memory access?
Ans: Direct Memory Access (DMA) allows peripherals to access the main memory
directly without involving the CPU, enabling high-speed data transfer.
6. What are privileged instructions?
Ans: Privileged instructions are processor commands that can only be executed in
supervisor or kernel mode to protect system stability and security.
7. What is pipelining?
Ans: Pipelining is a technique used in CPUs where multiple instruction phases are
overlapped to improve performance. It allows the next instruction to begin before the
previous one finishes.
