Chapter 4: An Overview of System Components

Exam Objectives

Introducing the basic components that make up personal computers

Identifying the fundamental principles that apply to personal computers

This chapter defines basic terminology and provides a brief overview of many topics that are covered in this book. By the time you finish reading this chapter, you should have a good understanding of the major components of the personal computer, from the motherboard to the monitor.

In preparation for the rest of the minibooks, I give you an overview of the major elements that make up the modern computer. As an A+ Certified Professional, you must be aware of these components, be able to service and manage these components, and be able to explain computing concepts to other people.

What Is a Computer?

Computers are a major element of our society, and they exist in so many places that we tend to forget that they are there. In simple terms, all computers are made up of four basic functions:

Data input

Data output

Processing

Storage

These functions, along with their related devices, are illustrated in Figure 4-1. In this chapter, I briefly introduce each of these functions and devices, which are covered in depth in Book II, Book III, and Book VIII.

Although the packaging of these functions takes very different shapes, from smartphones and digital video recorders (DVRs) to routers, laptops, and tower computers, they all share these functions at the most basic layer. The CompTIA A+ Certification exam focuses on the common arrangement of devices performing these four functions — typically called the personal computer — and not the more obscure arrangement of devices (such as the automobile engine idle controller). The rest of this chapter guides you through the major components in the personal computer.

Looking inside the Box

Most of the processing and storage devices show up “inside the box.” This section gives you a look at the major elements that you will find inside the system housing, or case.

Processor/CPU

The processor (also known as the central processing unit, or CPU) is the “brains of the organization,” so to speak. It is designed to do very few things, but to do them extremely quickly. The processor performs a limited set of calculations based on requests from the operating system and controls access to system memory. Processor speed is measured in several different ways, including clock cycles or megahertz (MHz), and millions of instructions per second (MIPS). Any of these measures give you an estimate of the processor’s speed/power.

The speed of early processors ranged from 4 MHz to 8 MHz, but today’s processors have broken the multi-gigahertz (GHz) mark. With the advent of multiple core processors, the processor’s speed is usually represented as a “per core” value.

You can find processors covered in detail in Book II, Chapter 2.

Storage devices

Storage devices on your computer are responsible for storing data, such as the operating system, applications, and actual output of applications or user data. Depending on the amount and type of data, the five basic types of devices to work with are

Floppy drives, including some of the high-capacity formats (such as 120MB SuperDisks).

Hard drives, including some of the removable cartridge drives (such as SyQuest drives).

Solid-state drives (SSD), like hard drives. These drives are internal drives to store data, but unlike hard drives, these drives do not have moving parts, but rather use flash memory to store data.

Optical drives, including CD-ROM and DVD drives.

Magnetic tape drives, which come in a variety of capacities and are usually used for archiving data.

Flash drives, which store data in a variety of nonvolatile memory chips.

Any one of these formats enables your computer to store and retrieve data. Each of these storage options is considered to be long-term or permanent storage, but either descriptor is relative because each media format has a limited lifespan.

When dealing with storage devices, the four major technologies used to connect hard drives to motherboards are

IDE (Integrated Drive Electronics) or ATA (Advanced Technology Attachment)

SATA (Serial ATA)

SCSI (Small Computer System Interface)

SAS (Serial Attached SCSI)

An ATA controller allows the 40-pin IDE connector to accept a wide variety of devices while maintaining full backward-compatibility with traditional IDE drives or devices. In most cases, IDE and ATA are used interchangeably, while the current systems are technically using ATA technology. There has been a long, ongoing battle for speed and performance between IDE (or ATA) and SCSI; in general, SCSI provides faster and more reliable transportation, and IDE has been the low-cost alternative. SATA is IDE’s younger cousin, and helps in IDE’s fight to challenge the benefits of SCSI, which has had its support bolstered by SAS.

Do not forget that ATA and IDE terms are used interchangeably, but you do not want to confuse these terms with Serial ATA, which uses different technology.

Within a computer, a bus is a mechanism that is used to move data between devices of the computer, much like how a city bus is used to move people between bus stops in the city. Hard drives are manufactured as ATA, SATA, SCSI, or SAS devices, and they are usually connected to the motherboard through the high-speed PCI (Peripheral Component Interconnect) bus. However, being internal devices, they cannot be easily transported between computers. The USB, IEEE 1394 (or FireWire), and PCMCIA (PC Card) buses provide fast-enough data transfer to allow hard drives to be attached to a system using these technologies, and are designed to be used with external devices. Many manufacturers have products that allow standard ATA or SATA drives to be connected using these buses. Because of the higher cost and the difference in technology, SCSI drives are not normally used.

Although SATA is usually thought of as an internal technology, there has been a rise in popularity of eSATA (External SATA), which provides an external connector to the SATA bus. Some external USB hard drives also support eSATA connectors.

The type of drives that you can attach to your computer depends on the types that are supported by your motherboard and I/O (input/output) cards.

You can investigate what you need to know about hard drives and storage devices for the A+ exam by going to Book II, Chapter 5.

Memory

Memory is a solid-state (that is, no moving parts) storage medium. It can take many forms, such as RAM (random access memory), flash RAM, ROM (read-only memory), or EPROM (erasable programmable ROM). Access time for RAM is measured in nanoseconds (one-billionth of a second). When memory is discussed, it usually refers to RAM, which is the computer’s primary working memory. RAM is a form of storage albeit typically temporary storage. Many people might not think of RAM as a storage medium because it is volatile and loses its information when power is removed, but temporary storage is still storage.

RAM is always temporary, and requires power to retain information. When you put your computer into a hibernation state, the contents of RAM are written to a file, and then retrieved when you power up your computer.

An analogy that I often use when talking about RAM is that of a tabletop (RAM) and a filing cabinet (hard drive or magnetic tape). People will not argue the point that a filing cabinet is a storage area for my papers, but they might dispute that a tabletop is a storage area. When I want to work with my papers, I take them out of the filing cabinet, and place them in temporary storage on my tabletop, where I am able to read the papers and make changes to them. When I am done, I will place the papers back in the permanent storage of the filing cabinet. I know some people who would use their tabletop as a form of permanent storage. Just like with RAM, my tabletop has a limited space, so when it becomes full, I will find that my work gets slower as I have to shuffle papers about. When the OS loads, it loads into RAM; when applications load, they load into RAM; when you open documents, they load into RAM; and when you need to send output to your monitor, the output is loaded into RAM before it appears on your monitor.

In addition to working memory, RAM is used in many areas of your computer. In most situations, it is used for caching data or dedicated to specific subsystems. Most video cards will have dedicated RAM on the video card, and processors and hard drives have special high-speed RAM for caching.

To be able to answer all of the memory questions on the A+ exam, read through Book II, Chapter 3.

System boards

The term system board describes any number of circuit boards that make up the internals of your computer, but it is used most often to describe the motherboard. The motherboard is the main board in your computer that contains the BIOS chips, RAM, I/O ports, and CPU. This board maintains the electrical pathways that enable all other components to communicate with each other.

Some service manuals use the term daughter board to describe a secondary board that contains motherboard functions, such as disk or I/O control. A daughter board is a board that contains some of the chips that could have been put on the motherboard but were not — perhaps because of space limitations or for other reasons. It is common to see them used in laptops and other mobile devices.

Motherboard information required for the A+ exam can be perused in Book II, Chapter 1.

Power supply

The power supply does exactly what its name suggests: It supplies power to the rest of the components in the computer. The power supply takes 120 or 240 volts (depending on the country you are in) of alternating current (AC) from your electrical outlet and converts it to 3.3 V, 5 V, and 12 V of direct current (DC). It contains a number of leads that supply different voltages for different types of devices (such as floppy drives and hard drives).

Book II, Chapter 7 provides you with all the information you need to answer the power supply questions on the A+ exam.

Adapter cards

Adapter cards allow you to adapt your computer to another role (such as controlling assembly line robots) or to add specific functionality to your computer (such as printing). The most common adapters are now integrated into most motherboards. These components include display, network, keyboard controller, mouse controller, serial ports, parallel ports, FireWire ports, and USB ports.

When the first computers came out on the market, most of the elements (if not all of them) were added to the motherboard by using the adapter slots, such as ISA, PCI, PCI Express, and AGP (well, ISA anyway, because the other slots did not exist).

Cooling system and fans

As electricity moves through any circuit, heat is generated, which is illustrated by looking at a simple circuit that contains an incandescent light bulb. As electricity moves through the bulb, the filament heats to glowing. Heat is also generated while electricity moves through the integrated circuits that are contained in most of the components of the computer. In addition to these fixed integrated circuits, hard drives contain moving parts that generate heat from friction. These components generate a large amount of heat, which needs to be removed from the critical components to prevent them from failing early in their careers.

To remove heat from computer systems, there has been a steady increase in the use of fans, vents, and other heat-dissipation units. Heat sinks with fans are commonly placed on processors and critical chipsets. Heat sinks are made of heat-conductive metals (usually aluminum or copper), with a solid side in contact with the chip that they are protecting and thin fins on the other side, thus putting greater surface area with the air, which helps dissipate or transfer heat to the air. The use of a fan with the heat sink allows more cool air to flow through the fins. Case vents and fans bring cool air into the computer housing, and also vent and pull out hot air.

Faster processors produce more heat. As processors have become faster, more methods for pulling the heat away from the processor have been developed, such as liquid-cooled devices.

You will find answers to A+ exam questions related to cooling processors in Book II, Chapter 2; and for overall systems in Book IV, Chapter 1.

Firmware and chipsets

People like to keep their world in a perceived state of order to give themselves a sense of control. This is often seen by how we classify everything we see or work with into categories. Many of these categories seem very distinct until something comes along to challenge our opinions, and then the waters become murky.

One of these murky areas is the distinction between hardware and software, which at one point were thought to be distinct and separate. Software is programming code that is stored on your disk or on some other form of media. Hardware refers to the physical components — boards, peripherals, and other equipment — that make up your computer.

Firmware fills in a middle ground between software and hardware, where the distinct line begins to disappear. Firmware is programming code (software) that is contained in or stored on the IC (integrated circuit) chips (hardware) on your computer. This combination of hardware and software makes up the BIOS on several different devices, with settings stored in CMOS or flash RAM. This firmware is tied to the function of the IC chips that it is working with; in the case of a network card, firmware would manage network or PXE (Pre-eXecution Environment) boot functionality of the card.

Most modern motherboards have a series of IC chips and firmware that work together to control the integrated functions of the motherboard. The compatibility of these chips and the code that ties them together is provided by a single supplier, and this group of chips is referred to as a chipset. Intel and VIA Technologies produce popular chipsets.

BIOS

BIOS is short for basic input-output system. The BIOS is actually software that is stored on a ROM chip on the motherboard. Most systems today use a flash EPROM to store the BIOS so that the user can update the programming code in the BIOS.

The BIOS is responsible for controlling or managing low-level but extremely important processes like the POST (Power-on Self-Test), the boot process, and the interaction of components on the motherboard.

Book II, Chapter 4 provides you with all the facts that you will need to answer BIOS questions on the A+ exam.

CMOS

CMOS (complementary metal-oxide semiconductor) is the type of manufacturing process that creates most integrated circuits. This development process is used to create the following:

High-density DRAM (dynamic RAM)

High-speed processors

Low-power devices for mobile use

The term complementary refers to the fact that these chips use negatively and positively charged transistors (which complement each other) to store information. Most RAM chips rely on CMOS technology to store information, but when discussing CMOS, you will probably be referring to the hardware configuration settings that are saved between reboots of your computer. These settings include

Which hard drives and floppy drives are present

How much memory is installed

Whether booting requires a keyboard

The type of mouse installed (PS/2 or serial)

What are the reserved resources (such as IRQ [interrupt request], I/O addresses, and DMA [direct memory access] channels)

What is the power-on password and whether it is required to boot up the system

The date and time

Whether ACPI (Advance Configuration Power Interface) is enabled and what devices it applies to

To be ready for your A+ exam, review the CMOS information, such as common settings, in Book II, Chapter 4.

Remember that BIOS stores programming code, and CMOS stores settings for the BIOS options.

Checking outside the Box

Now that you have looked at what is inside the box, you will want to see what gets added to the system — outside the box.

Casing and form factors

Part of the outside of the box is the box itself. There are many different form factors for the box, some of which dictate the form factor of the motherboard going into the case. Cases come most often in tower or desktop form factors, but are also found in forms that make them attractive for entertainment units and in extremely small forms for specific uses.

Input and output devices

Computers use many different kinds of input and output devices (also called I/O devices), which connect to the computer via one of the computer’s ports. In the following sections, I give you an overview of the most common input and output devices.

Monitor

The different types of buses that can provide video services include

ISA (Industry Standard Architecture), which ran at 8 MHz and carried 8 to 16 bits of data (approximately 8 MBps). Although mentioned here, you will be hard pressed to find new systems using this bus, but you may find these in action running monitor and control systems in manufacturing facilities.

PCI (Peripheral Component Interconnect), which runs at 33 MHz and 66 MHz and carries 32 bits of data (approximately 132 MBps or 264MBps).

PCIe (Peripheral Component Interconnect Express), or PCI Express is a high-speed serial bus, so its speed is measured differently than the others, which are parallel buses.

PCIe has between 1 and 16 channels (1x–16x). Depending on the version (version 1.x, 2.x, or 3.0), PCIe can carry data at 250 MBps, 500 MBps, or 1 GBps, per channel, per direction. ISA, PCI and PCI-X are half duplex — data can only flow in one direction at a time; while PCIe is full duplex — data may flow in both directions simultaneously. For a 16-channel card, the speeds for the three versions would be 4 GBps, 8 GBps, or 16 GBps.

PCI-X (Peripheral Component Interconnect Extended), which runs at 133 MHz and carries 32 to 64 bits of information. This provides a maximum throughput of approximately 532 MBps per direction.

AGP (Accelerated Graphics Port), which runs at 66 MHz (but can be increased to 8x the base speed, or 528 MHz) and carries 64 bits of data (approximately 2 GBps).

You have probably already guessed that the faster the bus speed, the faster your video card is likely to function. The AGP bus was designed specifically for video and is being replaced by PCIe. In addition to a fast bus speed, video performance and color depth are provided by RAM or video RAM. This RAM is found on the video card itself. Some high-end video cards also have a small processor (graphics processing unit or GPU) to handle some of the work of displaying information on your monitor instead of letting the computer’s main processor do all the work.

The processing done by some video cards can require that the card receive additional power from the power supply, rather than relying solely on the power provided by the bus. This is why some power supplies have a special 12VDC connector for your video card.

Video cards traditionally allow for color depths that include

4-bit or 16 colors

8-bit or 256 colors

16-bit or 65,000 colors

24-bit or 16 million colors

32-bit or 4 billion colors

Standard screen resolutions are (in pixels)

640 x 480

800 x 600

1024 x 768

1152 x 864

1280 x 1024

1600 x 1200

With the prevalence of wide-screen monitors (16:10 ratio), standard wide-screen resolutions are (in pixels)

768 x 480

1024 x 640

1152 x 720

1280 x 800

1680 x 1050

1920 x 1200

Modern video cards follow the SVGA (Super Video Graphics Array) standard, but all support at least VGA. The VGA standard is output in 16 colors at 640 x 480.

Review Book III, Chapter 3 to fully understand monitors and video.

Modem

Modem is short for modulator/demodulator. Modulation refers to the conversion of a digital signal to an analog signal, and demodulation reverses this process. Your computer is digital, and phone lines that you want to communicate over are analog. In order to allow the digital signal to be passed over the analog lines, you must use a modem.

Modems allow computers to communicate with each other if they are placed where there are phone lines. Prior to modems, there was no low-cost means of connecting distant computers; your only choice was an expensive, dedicated, leased phone line from the telephone company. The speeds at which modems operate have been increasing since their invention. They started with transfer rates of 300 bps (bits per second) and have moved up to 115 Kbps.

Today, where modems were traditionally used, they are often replaced by other remote connectivity options, such as an alphabet of DSL (Digital Subscriber Line) options, ISDN (Integrated Services Digital Network), and broadband cable. Each of these systems has a device — a modem — to connect your Ethernet network card to the data network. DSL and broadband cable send the signals over analog networks and modulate your data signal to previously unused frequencies. ISDN is digital on both sides of the connection, so there is no modulation taking place. The correct term for this device would be a TA (terminal adapter) and not a modem.

Standard modems connect to your computer through the serial port and can be either

Synchronous (kept in synchronization by an external clock)

Asynchronous (kept in synchronization by control signals in transmission)

Most modems that are purchased for a computer are asynchronous.

To prepare yourself for modem questions on the exam, read through Book III, Chapter 2.

Ports

Sailing ports provide a location for ships to load and unload goods from one location to another. On your computer, ports act as connection points for cables, which allow for the transfer of data between your computer and another device. Several different types of connectors and cables are used to join devices. Although the list of devices that communicate through the different types of ports is limitless, some of the basic types of ports and their uses are listed in Table 4-1.

Table 4-1 Basic Types of Ports

Port	Use
Serial	Connects serial devices, such as modems, to your computer.
Parallel	Connects parallel devices, such as printers, to your computer.
Video	Connects a monitor to your computer.
USB	Connects various types of devices to your computer. Devices that used other ports in the past are increasingly being converted to use USB ports. Devices that use this port include printers, modems, mice, keyboards, and scanners.
Keyboard	Connects a keyboard to your computer.
Mouse	Connects a mouse to your computer.

Reading through Book III, Chapter 1 will give you a full appreciation of all of the types of ports, cables, and connectors that are used by computers.

Getting an A+

This chapter provides an overview of the major components found in a computer system, including

System boards, which contain most of the computer circuitry

Power supply, which converts a building’s AC to usable DC for the ­computer

Processor/CPU, which efficiently executes instructions for the OS

Memory, which holds working data and application code

Storage devices, which are long-term or short-term storage areas

Monitor, which displays data from the computer

Modem, which communicates with other devices

Firmwware, which is a cross-breed between hardware and software

BIOS, which are low-level internal communication routines

CMOS, which is a storage area for configuration settings

Ports, which are used as connection points for other devices

Prep Test

1 Which of the following components is not usually found on a motherboard?

A BIOS chips

B USB drives

C Memory

D I/O ports

2 What type of memory loses its contents when power is turned off on your computer?

A CMOS memory

B RAM

C ROM

D EPROM

3 A standard North American power supply converts 120 V AC to which of the following? (Select all that apply.)

A 3.5 V DC

B 3.3 V DC

C 6 V DC

D 12 V DC

4 What is the primary purpose of the processor?

A To convert digital signals into analog signals

B To process signals so that they can be displayed on your monitor

C To carry out instructions from the operating system

D To convert 16-bit data into 8- or 32-bit data

5 What unit is used to measure RAM speed?

A Milliseconds

B Gigaseconds

C Picoseconds

D Nanoseconds

6 Which two of the following represent hard drive architectures?

A PCI

B IDE

C CMOS

D SCSI

7 What standard do most current monitors follow?

A VGA

B SVGA

C CGA

D FLAT

8 Modems are usually attached to a computer through what type of port?

A Serial

B Sequential

C Parallel

D Modem

9 Firmware is composed of which of the following? (Choose two.)

A Software

B Middleware

C Hardware

D Componentware

10 The programs that allow the POST to take place are stored in what?

A BIOS

B CMOS

C RAM

D POSTOS

11 What does CPU stand for?

A Core predetermination utility

B Complementary provider unit

C Central processing unit

D Co-primary uniprocessor

12 What does CMOS stand for?

A Complementary metal-oxide semiconductor

B Co-management of operating system

C Configuration management and option semiconductor

D Configuration memory option system

Answers

1 B. The motherboard will include I/O ports or connectors for a variety of devices, but will not typically include the devices themselves. It will include the ATA controller and also a connector to attach the ATA drive, but not the drive itself. The same would be true of USB drives; the motherboard will include the controller and connector for the USB bus but not the actual device. See “System boards.”

2 B. RAM memory is volatile, or non-permanent, because it loses its contents when power is turned off on the computer. Review “Memory.”

3 B, D. Power supplies have leads that supply 3.3 V, 5 V, or 12 V. Check out “Power supply.”

4 C. Processors carry out instructions that they receive from the operating system. Peruse “Processor/CPU.”

5 D. The normal measurement for RAM is nanoseconds, or billionths of a second. Take a look at “Memory.”

6 B, D. Hard drive architectures used with computers are IDE (or ATA), Serial ATA (SATA), SCSI, and Serial Attached SCSI (SAS). Peek at “Storage devices.”

7 B. Super Video Graphics Array (SVGA) is the current graphics standard that monitors follow. Look over “Monitor.”

8 A. Modems are serial devices, and as such are attached to the serial port. Study “Modem.”

9 A, C. Firmware consists of programming code or software that is contained within a hardware component such as a ROM chip. Refer to “Firmware and chipsets.”

10 A. BIOS contains the programs that allow the POST to take place. The BIOS is stored on a ROM or an EPROM. See “BIOS.”

11 C. Central processing unit. Review “Processor/CPU.”

12 A. Complementary metal-oxide semiconductor. Check out “CMOS.”