HANDOUT – CPU Explained Objective 101.04 What is a CPU? The CPU, Central Processing Unit, is the brain of the PC. It may also be referred to as the processor or central processor. A CPU is really a microprocessor or MPU that is made up of millions of transistors on a silicon wafer. The transistors act like tiny switches that are either turned on or off. The CPU uses these switches to execute a sequence of stored instructions called a program. There are four basic processes in the execution of instructions: 1. Fetch 2. Decode 3. Execute 4. Write-back. All the work done by a CPU is done using binary numbers – either a 1 or a 0. The 1 is the switch in the on position causing a presence of voltage, and the 0 is the switch in the off position causing an absence of voltage. The CPU has an Arithmetic Logical Unit or ALU that performs arithmetic and logical operations on the binary numbers. The CPU also has a Control Unit that extracts instructions from the memory, decodes and executes the instructions. CPU Manufacturers Intel IBM used to control the PC industry and market. IBM worked with a company called Intel, which manufactured CPUs for IBM. Over time, Intel has become the world leader in microprocessor development. Intel develops their chips, which fall into generations or families. The first generation was the 8080, 8088, and the 8086 chips. The next generation was the 80286, 80386, and 80486 chips. The next family was the Pentium 1, Pentium Pro, P2, P3 and P4 microprocessors. Other families of Intel CPUs are o Core o Celeron o Xeon (Server) o Atom (Mobile Computer) Page | 1 HANDOUT – CPU Explained Objective 101.04 AMD Intel is not the only microprocessor manufacturer out there. Advanced Micro Devices (AMD) is a manufacturer that started making chips the same time Intel did. In the beginning, AMD made chips almost identical to Intel’s, but because of legal battles and changes in the computing industry, AMD has developed their very own CPU architecture. AMD was the first to produce chips that could process 64 bits of data per clock. AMD produces the following CPU families: Phenom Athlon Duron Sempron Opteron (Server) Turion (Mobile Computing) CPU packages Many different CPUs have been developed over time. With each new model, from each manufacturer, there have been changes in the size, shape, voltages, signals, number of pins, shape of the pins and style of CPUs. These packages include single edge cartridge (SEC), pin grid array (PGA), and land grid array (LGA). Every MB has a CPU socket which must match the exact specifications of a specific CPU. There is no guessing. A MB is completely configured around the specific abilities of a specific CPU. Nearly every new advancement in CPU technology brings a change in package. Page | 2.