A computer requires both hardware and software to work.
The four basic functions of the microcomputer are input, output, processing, and storage
Data and instructions are stored in a computer in binary form, which uses only two states
for data—on and off, or 1 and 0—which are called bits. Eight bits equal one byte.
The four most popular input/output devices are themouse, keyboard, printer, and
The most important component inside the computer case is the motherboard, also
called the main board or system board. It holds the most important microchip inside
the case, the central processing unit (CPU), a microprocessor or processor. The
motherboard also gives access to other circuit boards and peripheral devices.
All communications between the CPUand other devices must pass through the
1CHAPTER 1 28 Introducing Hardware
Most microchips are manufactured using CMOS (complementary metal-oxide semicon-
Each hardware device needs a method to communicate with the CPU, software to control
it, and electricity to power it.
Devices outside the computer case connect to the motherboard through ports on thecase. Common ports are network, FireWire, sound, serial, parallel, USB, keyboard, and
An adapter card inserted in an expansion slot on the motherboard can provide an inter-
face between the motherboard and a peripheral device, or can itself be a peripheral. (An
example is a network card.)
The chipset on a motherboard controls most activities on the motherboard.
Primary storage,called memory or RAM, is temporary storage the CPU uses to hold data
and instructions while it is processing both.
Most RAM sold today is stored on memory chips embedded on memory modules, which
are called DIMMs.
Secondary storage is slower than primary storage, but it is permanent storage. Some
examples of secondary storage devices are hard drives, CD drives, DVD drives, Blu-ray
drives, ﬂashdrives, memory cards, Zip drives, and ﬂoppy drives.
Most older hard drives, CD drives, and DVD drives use the parallel ATA (PATA) interface
standard, also called the EIDE (Enhanced Integrated Drive Electronics) standard, which
can accommodate up to four EIDE or IDE devices on one system. Newer drives use the
serial ATA (SATA) interface standard.
The system clock is used to synchronize activityon the motherboard. The clock sends
continuous pulses over the bus that different components use to control the pace of
A motherboard can have several buses, including the system bus, the PCI Express bus, the
PCI bus, and the older AGP bus.
The frequency of activity on a motherboard is measured in megahertz (MHz), or one mil-
lion cycles per second. The processor operates at amuch higher frequency than other
components in the system, and its activity is often measured in gigahertz (GHz), or one
billion cycles per second.
The power supply inside the computer case supplies electricity to components both inside
and outside the case. Some components external to the case get power from their own
A ROM BIOS or ﬁrmware microchip is a hybrid of hardwareand software containing
programming embedded into the chip.
ROM BIOS on a motherboard holds the basic software needed to start a PC and begin
the process of loading an operating system. Most ROM chips are ﬂash ROM, meaning
that these programs can be updated without exchanging the chip.
The BIOS setup program is part of ROM BIOS stored on the ﬁrmware chip. This pro-
gram is used to changemotherboard settings or conﬁguration information. When power
to the PC is turned off, a battery on the motherboard supplies power to CMOS RAM
that holds these settings.
REVIEWING THE BASICS
1. Why is all data stored in a computer in binary form?
2. What are the four primary functions of hardware?
3. What are the two main input devices and two main output devices?
4. What three things do...