Computer Architecture & Organization: Chapter 4 - INSTRUCTION SET COMPUTING

What is the definition of an instruction set?

It is the set of operations provided by a processor, determined by its design and implementation.

How is Instruction Set Architecture (ISA) defined?

The design of a computer from the programmer’s perspective.

What are the three essential elements of a machine instruction?

The operation code (opcode), source operand reference, and result operand reference.

What are the five main types of instructions?

Data transfer/movement, arithmetic, logical, transfer of control (branching), and processor control.

What characterizes CISC architecture?

A design where single instructions can execute several low-level operations and use many addressing modes

What characterizes RISC architecture?

A strategy based on a simplified instruction set that executes instructions in fewer microprocessor cycles

Contrast instruction length between RISC and CISC.

RISC uses fixed-length instructions, while CISC uses variable-length instructions

Which architecture uses a "load-store" model?

RISC memory is accessed only through specific load and store instructions.

Define immediate addressing.

The actual data value is provided directly as part of the instruction

Define Direct Addressing

The address of the operand is specified directly in the instruction.

Define Indirect Addressing

The operand field contains the address of a memory location that contains the actual address of the operand

What is register indirect addressing?

The instruction specifies a register that contains the address of the operand in memory

What are the three common uses of displacement addressing?

Relative addressing, base-register addressing, and indexed addressing

How is a "zero-address" instruction typically implemented?

Through Stack organization, where operations like ADD occur between the top items on a stack.

What is a "three-address" instruction?

An instruction that uses three fields to specify two source operands and one destination operand.

What is the purpose of the "Mode" field in an instruction format?

It specifies how the operand or effective address is determined.

What is the principal advantage of register addressing?

Speed, it requires no memory reference to get the data.

What is the main disadvantage of indirect addressing?

It requires multiple memory references to fetch a single operand

What is the principal advantage of Displacement addressing?

Flexibility.