How a Computer Processes Data Hardware
Major Components Involved: • Central Processing Unit • Types of Memory • Motherboards • Auxiliary Storage Devices
The Central Processing Unit • What is a CPU? • How Fast is your processor? • The Different Companies that make CPUs • The Control Unit • The Arithmetic Logic Unit • The Floating Point Unit
Types of Memory • Random Access Memory • Read Only Memory • Cache • Registers
Motherboards • Chipsets • Slot A / Slot 1 / Super 7 • Expansion Slots • The Data Bus / The Address Bus • Overclocking
Central Processing Unit • The CPU is referred to as the brain of the computer. • Every computer must have at least one CPU. • The CPU is connected to the motherboard.
How Fast is Your Processor? • The most popular way to distinguish between processors is by speed. • Processors perform instructions at extremely high rates. • The processors on the market now run (processes instructions) at 600 - 700 MHz.
How Fast is Your Processor? • Hz is a unit used to measure frequencies in physics. It means cycles per second. • 1 Hz = 1 cycle / s. In our case instructions / second. • The M in MHz refers to Mega or million. • Thus, a 650 MHz processor can process 650 million instructions (operations) every second.
How Fast is Your Processor? • The number of Hz that a processor is set to depends on an internal clock on the motherboard. • The internal clock is a quartz crystal that vibrates millions of times a second. • In GENERAL, a computer will run faster with a processor with a higher clock speed.
The Different Companies that make CPUs • There are three main companies that make CPUs for the PC and one for the Mac. • Intel, AMD and Cyrix are the PC CPU makers. • Intel and AMD make the greatest number of PC processors. • Motorola is the sole Mac CPU maker.
Intel Processors • Intel has made the majority of PC processors in the last 20 years. • Examples of processors that Intel has made in the last 8 years in order are: 486, Pentium, Pentium MMX, Pentium Pro, Pentium II, Celeron, Xeon, Pentium III. • All but the Pentium Pro and Xeon were meant for your home computer. The above two were meant for servers.
Intel • Some servers will have two processors to reduce bottlenecking. • This is called having a dual processor. It would normally be done with a Pentium Pro (the older server chip) or the Xeon (the newer server chip). The Celeron is now capable of this as well.
Socket 7 vs Slot 1 • Up until the last two years all processors were Socket 7 compliant. • That meant they fit into a socket on the motherboard. The socket was labelled Socket 7. • Before the Socket 7 there was a Socket 5 and so on.
Socket 7 vs Slot 1 • Most of the newer processors that Intel has made now use a Slot 1. • The only exceptions to that would be the Xeon that uses a Slot 2, Pentium Pro that uses the Socket 8, and the Celeron that now uses the Socket 370. • Celeron used to use a Slot 1. So they made a Slot 1 to Socket 370 converter.
Socket 8 CPU: Pentium Pro L2 cache Processor
Advanced Micro Devices • Up to recently, AMD has always sold the second most processors for the PC. • AMD is Intel largest competitor. • Some of the processors that AMD has developed in the past few years are the K5, K6, K6-II, K6-III and the K7 (Athlon).
AMD vs Intel • AMD has always seemed to have fallen short when putting the processor against Intel’s. The Pentium was faster than the K5. The Pentium II was faster than the K6 series. • It now seems that AMD has finally made a processor that is faster than Intel’s. The Athlon is quite a bit faster than the Pentium III.
AMD Processors • AMD has until recently used the Socket 7 for there processors. • So AMD’s K6 series could compete with the Pentium II and Celeron processors AMD modified there processor so it would work with a Super 7 motherboard. The Socket and Super 7 processors are extremely similar. The Super 7 allows the computer to run at a faster speed.
AMD Athlon • The Athlon processor looks very similar to the Pentium II and Pentium III that uses a larger cartridge. • The Athlon is referred to as a Slot A processor. • Currently, there are only 3 motherboards that support the Athlon Slot A processor.
Components of the Processor • The five main components of the processor are: ALU, Control Unit, and Main Memory, Floating Point Unit, L1 cache. • This is what makes two CPU different from each other. • How a processor is designed and uses the five components above make it unique. • AMD and Intel chips (processors) are very different. Because of these components.
The Control Unit • The control unit is used to direct the flow of data. • Each CPU has an instruction set that is contained in the control unit. • The instruction set contains all of the instructions that a CPU can process. • All commands must be broken down into instructions that correspond to the CPUs instruction set.
The Control Unit • It is important to know that each CPU will have its own instruction set. This is one of the things that allows a CPU to be unique. • Each sequel to a CPU usually contains the older instruction set plus some new instructions. • For example, the Pentium III contained an extra 70 instructions compared to the Pentium II.
The Arithmetic Logic Unit • The ALU is the portion of the CPU that is used to carry out mathematical operations that involve integers, as well as logical operations. Each CPU contains 2 ALUs. • The ALU contains a group of high speed memory locations called registers that allow the ALU to store data that is being processed.
Main Memory: Registers • Registers hold the data currently being processed and are located in the ALU. • The more data that can be held, the faster the processing will be. • The original PCs had 16 bit registers, then newer processors contain 32 bit registers. That means twice as much information can be processed.
Registers • Both the Pentium III and the K7 contain 32 bit registers. • The K8 by AMD is supposed to have 64 bit registers and thus will be called a 64 bit machine.
Registers • Another important feature of a CPU is the number of 32 bit floating point operations that it can processes. • The K6-II with 3DNow can process two instructions at one time, the Pentium III four. • What about the new Athlon?
Floating Point Unit (MMX or 3DNow) • If any floating point numbers (decimals) need processing, they are passed to a specialized processor called the FPU. • Most multimedia commands need to be processed in the FPU. • The FPU is capable of holding larger pieces of data, it contains 80 bit registers (can hold 80 bits at a time). Most multmedia fit into 64 bit registers.
Memory: Cache • There are two types of cache involved with processors. • L1 cache is located on the CPU, L2 cache is located beside the CPU or on the motherboard depending on the processor. • When data enters the CPU from the RAM, it places a copy of the data in both kinds of cache. Thus, the cache contains previously processed data.
Memory: L2 Cache • The L2 cache on a Pentium II is 512K. How much does Athlon and the Pentium III have? • The L2 cache on a Pentium II runs at half of the speed of the CPU. The Pentium Pro contains the L2 cache in the CPU and thus it runs at the same speed as the CPU.
Memory: L1 cache • The L1 cache is twice as fast as the L2 cache because it resides on the CPU (it is part of the CPU) • The L1 cache on a Pentium II is 16K. This is twice as much as a Pentium Pro since the Pentium Pro has faster L2 cache. • How big is the L1 cache for the PIII and the Athlon? How fast is it?
Flow of Data • A processor will spend time looking for data when processing. • The first place it will look will be the L1 cache, followed by the L2 cache, then the RAM, followed by the hard drive. • Each one takes quite a bit longer than the last.