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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