Describe the
components in the system unit
The system unit, sometimes called the chassis, is
a box-like case housing the electronic components of a computer that are used
to process data. System unit components include the processor, memory module,
cards, ports, and connectors. Many of the system unit’s components reside on a
circuit board called the motherboard. The motherboard contains many different
types of chips, or small pieces of semiconducting material, on which one or
more integrated circuits (IC) are etched. An integrated circuit is a
microscopic pathway capable of carrying electronic current. Each IC can contain
millions of transistors, which act as switches for electronic signals.
Explain how
the CPU uses the four steps of a machine cycle to process data
The central processing unit (CPU), also called a
processor, significantly impacts overall computing power and manages most of a
computer’s operations. The CPU contains the control unit and the
arithmetic/logic unit.
The control unit directs and coordinates most of
the operations in the computer. For every instruction, the control unit repeats
a set of four basic operations called the machine cycle:
·
fetching the instruction or data item from memory,
·
decoding the instruction into commands the
computer understands,
·
executing the commands, and, if necessary,
·
Storing, or writing the result to memory.
The arithmetic/logic unit (ALU) performs the
execution part of the machine cycle. Specifically, the ALU carries out three
operations:
Arithmetic operations – performing calculations, which
include addition, subtraction, multiplication, and division
Comparison operations – comparing data items to determine if
the first item is greater than, equal to, or less than the other item
Logical operations – working with conditions and logical
operators such as AND, OR, and NOT
Compare and
contrast various personal computer processors on the market today
A personal computer’s CPU usually is contained on
a single chip, which some call a microprocessor.
Intel is a leading manufacturer of personal
computer processors.
Most high-performance PCs use a processor from
Intel called the Pentium® processor.
A second Intel brand, called the Celeron™, is designed for less
expensive PCs.
Two more brands, called the Xeon™ and Itanium™
processors, are ideal for workstations and low-end servers. Intel-compatible
processors have the same internal design as Intel processors and perform the
same functions, but are made by other companies and often are less expensive.
An alternative design to the Intel-style
processor, the Motorola processor,
is found in Apple Macintosh and Power Macintosh systems.
A new type of processor designed for lower-costing
personal computers and Internet appliances, called an integrated CPU, combines functions of a processor, memory, and a
video card on a single chip.
Today’s processors are equipped with MMX™ technology, a built-in set of
instructions that manipulates and processes multimedia data more efficiently. Intel’s SSE instructions and AMD’s 3DNow!™ are two other
technologies that improve a processor’s performance of multimedia, the Web, and
3-D graphics. To optimize and extend battery life for notebook computers,
Intel® mobile processors use SpeedStep™
technology and AMD processors use PowerNow!™
technology.
Define a bit
and describe how a series of bits represents data
Most computers are digital, meaning they
understand only two discrete states: on and off. These states are represented
using two digits, 0 (off) and 1 (on). Each on or off value is called a bit
(short for binary digit), the smallest unit of data a computer can handle.
Eight bits grouped together as a unit form a byte. A byte provides enough
different combinations of 0s and 1s to represent 256 individual characters
including numbers, letters of the alphabet, punctuation marks, and other
characters.
The combinations of 0s and 1s used to represent
data are defined by patterns called coding schemes. Popular coding schemes are
ASCII, EBCDIC, and Unicode. Coding schemes make it possible for humans to
interact with a digital computer that recognizes only bits. Every character you
type on a keyboard is converted into a corresponding byte, a series of on/off
electrical states the computer can process.
