 2002 Prentice Hall Hardware Basics: Inside The Box Chapter 2

 2002 Prentice Hall 2 Topics What Computers Do Bits, Bytes, and Buzzwords The Computer’s Core The Computer’s Memory

 2002 Prentice Hall 3 Thomas J. Watson, Sr. The “emperor” of IBM Created a culture of invention IBM remains an industry leader and innovator

 2002 Prentice Hall 4 What Computers Do Receive Input Process Information Produce Output

 2002 Prentice Hall 5 What Computers Do Store Information

 2002 Prentice Hall 6 Input Devices The keyboard is the most common input device Pointing devices like the mouse also receive input

 2002 Prentice Hall 7 Output Devices Computers produce information and send it to the outside world. A video monitor is a common output device. Printers also produce output.

 2002 Prentice Hall 8 Process Information The processor, or central processing unit (CPU), processes information and performs all the necessary arithmetic calculations. The CPU is like the “brain” of the computer.

 2002 Prentice Hall 9 Store Information Memory and storage devices are used to store information Primary storage is the computer’s main memory Secondary storage uses disks or other media

 2002 Prentice Hall 10 Information Information comes in many forms Computers store information in digital form Text Numbers Sounds Pictures

 2002 Prentice Hall 11 Bit Basics A bit (binary digit)  is the smallest unit of information  can have two values: 1 or 0  can represent numbers, codes, or instructions On

 2002 Prentice Hall 12 Bits as Numbers Each switch can be used to store a tiny amount of information, such as:  An answer to a yes/no question  A signal to turn on a light Larger chunks of information are stored by grouping bits as units  8 bits (byte) = 256 different messages

 2002 Prentice Hall 13 Bits As Codes ASCII – American Standard Code for Information Interchange Most widely used code, represents each character as a unique 8-bit code.

 2002 Prentice Hall 14 Bits as Instruction The computer stores instructions as collections of bits. For instance, might instruct the computer to add two numbers. Other bit instructions might include where to find numbers stored in memory or where to store them.

 2002 Prentice Hall 15 Bits, Bytes, and Buzzwords  Byte  Kilobyte (KB)  Megabytes (MB)  Gigabytes (GB)  Terabytes (TB) = 8 bits = 1 Thousand Bytes = 1 Million Bytes = 1 Billion Bytes = 1 Trillion Bytes Terms used to describe file size or memory size:

 2002 Prentice Hall 16 The CPU and Memory The microprocessor that makes up your personal computer ’ s central processing unit, or CPU, is the ultimate computer brain, messenger, ringmaster and boss. All the other components — RAM, disk drives, the monitor — exist only to bridge the gap between you and the processor. Ron White, in How Computers Work

 2002 Prentice Hall 17 The CPU The CPU:  interprets and executes instructions  performs arithmetic and logical data manipulations  communicates with the other parts of the computer system.

 2002 Prentice Hall 18 The CPU The CPU is a complex collection of electronic circuits.  When all of those circuits are built into a single silicon chip, the chip is referred to as a microprocessor.  The circuit board that contains a computer’s CPU is called the motherboard or system board.

 2002 Prentice Hall 19 Compatibility & Speed When purchasing a computer, selecting a CPU is very important. The two most critical factors are: Compatibility Speed

 2002 Prentice Hall 20 Compatibility Software is written for a specific processor and may not be compatible with another CPU. Every processor has a built-in instruction set or vocabulary of instructions that only the processor can execute. CPUs in the same family are generally designed to be backward compatible so newer processors can process all of the instructions handled by earlier models.

 2002 Prentice Hall 21 Speed A computer’s speed is determined in part by the speed of its internal clock The clock is a timing device that produces electrical pulses to synchronize the computer’s operations. A computer’s clock speed is measured in units called megahertz (MHz), for millions of clock cycles per second

 2002 Prentice Hall 22 Speed Clock speed by itself doesn’t adequately describe how fast a computer can process words, numbers, or pictures. Speed is also limited by architecture and word size.

 2002 Prentice Hall 23 Speed Parallel processing places multiple processors in a computer. Most supercomputers have multiple processors that divide jobs into pieces and work in parallel on the pieces.

 2002 Prentice Hall 24 The Computer’s Memory RAM (random access memory):  is used to store program instructions and data temporarily  unique addresses and data can be stored in any location  can quickly retrieve information  will not remain if power goes off (volatile )

 2002 Prentice Hall 25 The Computer’s Memory ROM (read-only memory):  information is stored permanently on a chip.  contains startup instructions and other permanent data.

 2002 Prentice Hall 26 Buses connect to storage devices in open areas in the box called bays. Buses, Ports, and Peripherals Information travels between components through groups of wires called buses.

 2002 Prentice Hall 27 Busses also connect to slots inside the computer Sockets on the outside of the computer called ports. Buses, Ports, and Peripherals

 2002 Prentice Hall 28 Buses, Ports, and Peripherals Slots and ports also allow external devices called peripherals to be added to the system (keyboard, monitor, and mouse). Without peripherals, the CPU and memory are like a brain without a body.

 2002 Prentice Hall 29