INSTRUCTION PROCESSOR DESIGN Computer system architecture

Unit -IV
INSTRUCTION PROCESS DESIGN
VIDHYA B
ASSISTANT PROFESSOR & HEAD
Department of Computer Technology
Sri Ramakrishna College of Arts and Science
Coimbatore - 641 006
Tamil Nadu, India
1

Introduction to Computer
Architecture
Intel Microprocessor Family
Multicore Processors
CPU Instruction Execution Steps
-Pipelining
Disk Controller
Microcomputer Bus
2
Sri Ramakrishna College of Arts & Science

Instruction Process Design
• Instruction processor design, often referred to
as INSTRUCTION SET ARCHITECTURE (ISA), is
a crucial aspect of computer engineering.
• It defines how a computer’s CPU is controlled
by software, specifying the instructions the
processor can execute, the data types it can
handle, and the registers it uses.
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Here are some key components of instruction
processor design:
• Instruction Set: This includes the set of operations
the processor can perform, such as arithmetic
operations, data transfer, and control operations
• Instruction Format: This defines the layout of the
bits in an instruction, including the opcode
(operation code) and operand(s) (data or memory
addresses)
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• Memory Model and Addressing Methods:
This describes how memory is accessed and
managed, including different addressing
modes like direct, indirect, and indexed
addressing.
• Registers: These are small, fast storage
locations within the CPU that hold data and
instructions currently being processed.
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• Modern processors also incorporate advanced
techniques like pipelining, which allows
multiple instructions to be processed
simultaneously, and branch prediction, which
improves the flow of instruction execution.
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Designing an Instruction Set
• Designing an instruction set involves several key
considerations to ensure the processor can
efficiently execute a wide range of tasks.
Here’s a step-by-step guide to design an instruction set:
1. Define the Instruction Set Architecture (ISA)
2. Instruction Categories
3. Addressing Modes
4. Register Set
5. Encoding and Instruction Formats
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1. Define the Instruction Set Architecture (ISA)
Types of Instructions: Determine the types of operations
the processor will support, such as arithmetic, logic, data
transfer, and control operations.
Instruction Format: Decide on the layout of the
bits in an instruction. Common formats include
fixed-length and variable-length instructions.
Operand Types and Sizes: Specify the types of
operands (e.g., immediate, register, memory) and
their sizes (e.g., 8-bit, 16-bit, 32-bit
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2. Instruction Categories
• Arithmetic and Logic Instructions: Include
operations like addition, subtraction, AND, OR,
etc.
• Data Transfer Instructions: Define how data is
moved between registers, memory, and I/O
devices.
• Control Instructions: Include instructions for
branching, jumping, and procedure calls.
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3. Addressing Modes
• Direct Addressing: The operand is
specified directly in the instruction.
• Indirect Addressing: The instruction
specifies a memory location that
contains the address of the operand.
• Indexed Addressing: Combines a base address
with an index to get the effective address.
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4. Register Set
• General-Purpose Registers: Used for a variety of operations.
• Special-Purpose Registers: Include the program counter, stack
pointer, and status register.
5. Encoding and Instruction Formats
• Opcode: The part of the instruction that specifies the
operation to be performed.
• Operands: The part of the instruction that specifies the data to
be operated on.
• Instruction Length: Decide whether to use fixed-length or
variable-length instructions.
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Example: Simple Instruction Set
Here’s a basic example of a simple instruction set:
• ADD R1, R2, R3: Add the contents of R2 and R3, and store
the result in R1.
• LOAD R1, 1000: Load the value from memory address 1000
into R1.
• STORE R1, 1000: Store the value of R1 into memory address
1000.
• JMP 2000: Jump to the instruction at memory address 2000.
• BEQ R1, R2, 3000: Branch to address 3000 if the contents of
R1 and R2 are equal.
• Designing an instruction set is a complex task that requires
balancing simplicity, efficiency, and flexibility
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Data Movement Instruction Set
Data movement instructions: It is essential for
transferring data between different parts of a
computer system.
Here are some common types of data movement
instructions:
1. Load and Store Instructions
• Load (LD): Transfers data from memory to a register.
Example: LD R1, 1000 (Load the value from
memory address 1000 into register R1)
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1. Load and Store Instructions
• Store (ST): Transfers data from a register to memory.
Example: ST R1, 1000 (Store the value of
register R1 into memory address 1000)
2. Move Instructions
Move (MOV): Copies data from one location to
another.
Example: MOV R1, R2 (Copy the value of register R2
into register R1)
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3. Input/Output Instructions:
Input (IN): Reads data from an input device into a
register.
Example: IN R1, PORT1 (Read data from input port
PORT1 into register R1)
Output (OUT): Writes data from a register to an
output device
Example: OUT PORT1, R1,(Write the value of
Register 1 to output port PORT1)
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4. Stack Manipulation Instructions:
Push (PUSH): Places data onto the stack
Example: PUSH R1, PORT1 (Push the value of
register R1 onto the stack)
Pop (POP): Removes data from the stack.
Example: POP R1, PORT1 (Pop the top value
from the stack into register R1)
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4. Stack Manipulation Instructions:
Push (PUSH): Places data onto the stack
Example: PUSH R1, PORT1 (Push the value of
register R1 onto the stack)
Pop (POP): Removes data from the stack.
Example: POP R1, PORT1 (Pop the top value
from the stack into register R1)
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5. Type-Conversion Instructions
Convert (CVT): Converts data from one type to
another.
Example: CVT R1,R2 (Convert the value in
register R2 to a different type and store it in
register R1)
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INSTRUCTION PROCESSOR DESIGN Computer system architecture

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