What is the role of processor in computer
Central processing unit
A central processing unit, also called a central processor or main processor, is the electronic circuitry within a computer that executes instructions that make up a computer program. The CPU performs basic arithmetic, logic, controlling, and input/output operations specified by the instructions,
Processor. A processor, or "microprocessor," is a small chip that resides in computers and other electronic devices. Its basic job is to receive input and provide the appropriate output. ... Most desktop computers contain a CPU developed by either Intel or AMD, both of which use the x86 processor architecture
A processor (CPU) is the logic circuitry that responds to and processes the basic instructions that drive a computer. The CPU is seen as the main
Computer processor speed (CPU speed) is one of the most important elements to consider when comparing computers. The CPU
Central Processing Unit (CPU)
• CPU is the heart and brain
• It interprets and executes machine level instructions
• Controls data transfer from/to Main Memory (MM) and CPU
• Detects any errors
• In the following lectures, we will learn:
• Instruction representation
• Data transfer mechanism between MM and CPU
• The internal functional units of two different CPU architectures
• How these units are interconnected
• How a processor executes instructions
Instruction Representation
• CPU operation is determined by the instruction it executes
• Collection of these instructions that a CPU can execute forms its Instruction
Set
• An instruction is represented as sequence of bits, for example:
• Instruction is divided into fields
• Opcode indicates the operation to be performed, eg., 92 above indicates a
copy operation – we need two operands – one source and other destination
• Opcode represents
• nature of operands (data or address), operand 1 is address and operand 2 is data
• mode (register or memory), operand 1 is memory, and operand 2 is immediate data
1001 0010 0000 0011 1011 1011 1000 0001
9 2 0 3 B B 8 1
Opcode Operand1 Operand2
Basic Instruction Types
Not all instructions require two operands
• 3-address instructions
Operation Source1, Source2, Destination
e.g. Add A, B, C ; C = A + B
• 2-address instructions
Operation Source, Destination
e.g. Move B, C ; C = B
Add A, C ; C = C + A
Here Source2 is implicitly the destination
• 1-address instructions
e.g. Load A
Store C
• 0-address instructions
e.g. Stop
Simple Instruction Set
Assume we have a processor whose Instruction Set consists of four machine
language instructions
• Move from a memory location to a data register in CPU
• Move from a data register in CPU to a memory location
• Add the contents of a memory location to a data register
• Stop
Suppose our program for Z = X + Y looks like:
Move X, D0
Add Y, D0
Move D0, Z
Stop
This program is coded into machine instruction and suppose is loaded into memory
starting at location $0000 0000
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