UGC NET Computer Science December 2019 | Question 118

Question 118

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The Reduced Instruction Set Computer (RISC) characteristics are :
(a) Single cycle instruction execution
(b) Variable length instruction formats
(c) Instructions that manipulates operands in memory
(d) Efficient instruction pipeline
Choose the correct characteristics from the options given below :

1. 1. (a) and (b)
2. 2. (b) and (c)
3. 3. (a) and (d)
4. 4. (c) and (d)

Answer : 3. (a) and (d)

Explanation Question 118

Common RISC (Reduced instruction set computers) characteristics

• Load/store architecture (also called register-register or RR architecture) which fetches operands and results indirectly from main memory through a lot of scalar registers. CPU accesses memory only for Load and Store operations
• Fixed length instructions. Generally, the size of the instructions is 32 bits.
• Fused or compound instructions which are heavily optimized for the most commonly used functions.
• Efficient instruction pipeline implementations with goal of executing one instruction (or more) per machine cycle.
• Large uniform register set
• Minimal number of addressing modes. i.e. Simple and few addressing modes
• no/minimal support for misaligned accesses

Characteristic of Complex instruction set computer CISC:

• Complex instruction, hence complex instruction decoding.
• Instruction are larger than one word size.
• Instruction may take more than a single clock cycle to get executed.
• Less number of general purpose register as operation get performed in memory itself.
• Complex Addressing Modes.
• More Data types.

You can cleary say that characteristics (a) and (d) are RISC characteristics.

So, option 3 is correct answer

Reference 1 : Reduced Instruction Set Computer (RISC) characteristics

Reference 2 : RISC/CISC Characteristics

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