How Computers Work Chapter 1

Hardware Needs Software to Work Hardware – computer’s physical devices Monitor, keyboard, memory chips, hard drive Software – instructions that directs the hardware to perform a task.

Hardware Needs Software to Work Software uses hardware for 4 basic things: Input Processing Output Storage See figure 1-1 pg. 2

Hardware Needs Software to Work Hardware components also communicate data and instructions among themselves. Must have electrical power system.

User Interaction with Computer Software must convert instructions given by the user into a language the computer understands. The computer understands two things: Yes – which means “ON” No – which means “OFF” Figure 1-2 pg. 3

Binary Number System 1940 – John Atanasoff can up with the idea to store and read only two values in a computer system, ON and OFF. Either there was a charge , ON, or there wasn’t a charge, OFF. We use the numbers 1 and 0 to represent ON and OFF – binary number system.

Binary Numbering System A 1 or 0 is called a bit. Also called a binary digit. Bits are generally group in groups of 8. 8 bits make up a byte.

Counting Binary Numbers All counting and calculations use the binary number system. Counting goes as followed: 0, 1, 10, 11, 100, 101…….. All letters and numbers must be converted to binary code before being stored. Letter A – 0100 0001 Number 25 – 0001 1001 Figure 1-3 pg. 4

PC Hardware Components Chapter 1

Hardware Components Most input/output devices are located outside the case. Most processing and storage devices are found in the case. The CPU is the most important device in the case.

Microprocessor (CPU) Central to all processing done by the computer. Data received by the input devices is read by the CPU. Output from the CPU is written to output devices.

PC Hardware Components Each input, output, and processing component requires these elements to operate: A method for the CPU to communicate with the device. Software to instruct and control the device. Electricity to power the device.

A method for the CPU to communicate with the device Data must be either sent to the CPU or received from the CPU.

Software to instruct and control the device Hardware devices cannot work without software to run it. The software must have access to the CPU in order run the device. Each device responds to specific instructions based on the function of the device.

Electricity to power the device Electronic devices need electricity to run the device. All computers need to have a power supply to run. Usually an electrical outlet.

Hardware Input and Output Input/output devices are used to communicate with devices inside the computer. Accomplished by either cables, which attach to a connection called a port, or by a wireless connection. Most ports are found in the back of the computer. Figure 1-4 pg. 5

Input devices Keyboard – primary input device. Standard keyboard has 104 keys. Mouse – a pointing device used to move a pointer on the screen and to make selections. Can have 1, 2, or 3 buttons. Both a mouse and keyboard can have 6 pin connector (figure 1-5) or a USB connector.

Output devices Monitor – visual device that displays the primary output of the computer. Rated by the monitor’s resolution, which is the number of dots used to display. Printer – produces output on paper called a hardcopy. Most printers are either an ink-jet, laser, and solid ink.

Hardware inside the computer

Hardware inside the computer Most computers can have these devices: Motherboard containing the CPU, memory, and other components. Hard drive, DVD and CD-ROM. A power supply supplying electricity. Circuit boards used by the CPU to communicate to other devices. Cables connecting devices to circuit boards and the motherboard. Figure 1-7 pg. 8

Circuit boards A board that holds microchips, integrated circuits (IC’s), and the circuitry that connects these chips. Expansion Cards – circuit boards that are installed in long narrow expansion slots on the mother board. Expansion slots – Open slots used to additional components.

Circuit boards CMOS chips (complementary metal-oxide semiconductor) All circuit boards contain microchips which are manufactured using CMOS. Require less electricity and produce less heat.

Other components The other main components inside the computer look like small boxes, like the power supply, floppy drive, hard drive, and CD-ROM.

Cables Two types of cables are found inside the computer: Data cables – connect devices to one another. Flat and wide cables Power cables – supply power. Round and small cables

The motherboard

The motherboard The largest and most important circuit board. Also called the system board and main board. Contains the CPU. Because of the complexity and importance of the CPU, all devices are either installed on the mother board or connect to it.

The motherboard Devices that are not on the motherboard is called a peripheral device. Some ports stick outside the case to connect to external devices. Figure 1-8 pg. 9

The mother board Serial ports – named because data is transferred serially (one bit follows the next). Parallel ports – transmits data in parallel and is most commonly used by a printer. Universal Serial Bus ports (USB) – used by a number of input/output devices. 1394 port – used by high speed multimedia devices such as digital camcorders. Figure 1-9 pg. 10

Items found on the motherboard Processing components CPU – most important chip. Chip set – controls motherboard activities Temporary storage Random Access Memory (RAM) – holds data and instructions as they are processed. Cache memory – speed ups memory access.

Items found on the motherboard Components that communicate with the CPU with other devices. Traces – wires on the motherboard used for communication. Expansion slots – connect expansion cards to the motherboard. System clock – keeps communication in sync. Electrical system Provide power to the motherboard and expansion cards.

Items found on the motherboard Programming and setup data Flash ROM – a memory chip used to permanently store instructions that control hardware functions. CMOS chip – holds configuration data.

The CPU and the Chip Set The CPU could not do it’s job without the assistance of the chipset. Chipset – group of microchips on the motherboard that control the flow of data and instructions to and from the CPU. Figure 1-10 pg. 11 Figure 1-11 pg. 12

Storage Devices 2 types of storage: Temporary and Permanent CPU uses temporary storage called primary storage or memory. Primary storage is much faster to access than permanent memory.

Storage Devices When data and instructions are not being used, they are stored in permanent storage called secondary storage. Floppy disk, hard drive Figure 1-12 pg. 13

Primary Storage Primary storage is provided by devices called RAM Random Access Memory Located on the motherboard and other circuit boards RAM chips are installed directly on a small board on the motherboard or in banks that plug into the motherboard. Figure 1-13 pg. 14

Primary Storage The most common types of boards that hold memory are: Single Inline Memory Modules (SIMM) Dual Inline Memory Modules (DIMM) Rambus Inline Memory Modules (RIMM) Memory in RAM is lost when the computer is shut off. They need a continuous supply of electricity.

Primary Storage Because RAM always needs electricity, it is referred to as volatile memory. However, there is nonvolatile memory called ROM (Read Only Memory). Holds data even when no electricity is present. Figure 1-14 pg. 14

Secondary Storage Data that is stored on devices such as CD’s, disks, hard drives, and so on. Data and instructions can not be processed from these locations. It must first be copied to Primary Storage. IMPORTANT: secondary memory is PERMANENT memory.

Secondary Storage Hard drive – a sealed case containing platters and disks that rotate at a high speed. Figure 1-16 pg. 16 As platters rotate, an arm reaches across the platters, both writing new data and reading existing data.

Hard drives Hard drives use a technology called: Integrated Drive Electronics (IDE) IDE provides two connectors on a motherboard for two data cables. Figure 1-17 pg. 17 Figure 1-18 pg. 17 A motherboard can accommodate up to 4 IDE’s Hard drives, ZIP drives, CD-ROMs all use these IDE connections.

Hard drive Receives its power from the power supply by way of a power cord. Figure 1-19 pg. 18

Other Secondary Storage Devices Floppy Drive Holds up to 1.44 MB of data CD-ROM Drive Most software is distributed by CD-ROM

Motherboard Components use for Communication Among Devices Traces – circuits (paths) that enable data, instructions and power to transfer from component to component. This system of pathways used for communication and the protocol and methods used for transmission are called the bus.

Motherboard Components use for Communication Among Devices Protocol – set of rules and standards that any two entities use for communication. Data bus – paths, or lines of the bus that are used to move data. Figure 1-24 pg. 21

Motherboard Components use for Communication Among Devices Binary data is put on a line of a bus by placing voltage on that line. This voltage is traveling on top of the line, not on it.

Transferring data between components When one component at one end of the line wants to write data to another component, the two must get in sync for the write operation. The first component places voltage on several lines of the bus, and the other component immediately reads the voltage on those lines.

Transferring data between components The CPU interprets the voltage on each line as binary digits. Some buses have data paths that are 8, 16, 32, 64, or 128 bits wide. If a bus has 8 wires to transmit data, it is called an 8 bit bus. Remember: There are only two states inside a computer. On or Off. If there is a voltage, then it is represented by a 1, and just the opposite if there is no voltage. Figure 1-25 pg. 22

Bus Data Path Size – width of a data bus. There can be multiples buses on a motherboard. The main bus on the motherboard has several different names: System bus Memory bus Host bus Local bus Front Side bus (FSB)

System clock System clock – circuit dedicated to timing the activities of the chips on the motherboard. Figure 1-26 pg. 23 Clock speed – the number of beats which are measured in Hertz (Hz) Hertz – one cycle per second. Megahertz (MHz) – one million cycles per second. Gigahertz (GHz) – one billion cycles per second.

Transferring data between components The lines of a bus often expand to expansion slots. Figure 1-27 pg. 24 The kind of bus you depends on the type of expansion slot.

Expansion slots 3 general types of expansion slots: PCI (Peripheral Component Interconnect) Slot used for high-speed I/O devices AGP (Accelerated Graphics Port) Slot used for a video card ISA (Industry Standard Architecture) Slot used for older or slower devices Figure 1-27 pg. 24 Figure 1-28 pg. 24

Interface (Expansion) Cards Circuit boards, other than motherboards, are sometimes called circuit cards, adapter cards, expansion cards, and interface cards. Figure 1-30 pg. 25 Figure 1-31 pg. 26

Interface (Expansion) Cards Video Card – provides a port for the monitor to connect to. Sound Card – provides ports for speakers and microphones. Network Card – provides ports for a network cable to connect the PC to a network.

The Electrical System Most important component of the computer’s electrical system. Usually located near the back of the case. Power supply does not actually produce electricity. Converts it and reduces it to a voltage that the computer can handle.

Power Supply The power supply also runs a fan directly from the electrical output voltage to help cool the inside of the case. Temps over 185 degrees F. can cause damage. Every motherboard has one pair of connections to receive power from the power supply. Figure 1-32 on pg. 27 Figure 1- 33 on pg. 28

Power Supply Power supply can receive up to 120 AC power. Newer power supplies will convert that into 3.3, 5, and 12 volts of DC power.

Instructions stored on the Motherboard Basic instructions, which start the computer, are stored on the motherboard. This data is stored in ROM chips called BIOS. Basic Input-Output System Figure 1-34 pg. 29

Instructions stored on the Motherboard ROM BIOS serve 3 purposes: The BIOS that is sometimes used to manage simple devices is called system BIOS. The BIOS that is used to start the computer is called startup BIOS. The BIOS that is used to change some settings on the motherboard is called CMOS setup.

Plug and Play PnP – standard designed to make the installation of new hardware devices easier. The computer system BIOS will recognize the device, and will begin the configuration of the new device.