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Chapter 12

COMMERCE 2KA3 Chapter Notes - Chapter 12: Minicomputer, Word Processor, Uninstaller


Department
Commerce
Course Code
COMMERCE 2KA3
Professor
A L I R M O N T A Z E M I
Chapter
12

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Chapter 12: IT Architectures
Introduction
Hardware: consists of the physical devices associated with a computer
system
Software: the set of instructions that the hardware executes to carry out
specific tasks
Hardware Basics
Computer: an electronic device operating under the control of instructions in
its own memory that can accept, manipulate and store data
Six Hardware components:
oCentral Processing Unit (CPU): The actual hardware that interprets and
executes the program (software) instructions and coordinates how all
the other hardware devices work together
oPrimary storage: the computer’s main memory, which consists of the
random access memory (RAM), cache memory, and the read-only
memory (ROM) that is directly accessible to the central processing unit
(CPU)
oSecondary storage: equipment designed to store large volumes of data
for long-term storage
oInput devices: equipment used to capture information and commands
(e.g., keyboard, scanner)
oOutput devices: Equipment used to see, hear, or otherwise accept the
results of information processing requests (e.g., monitor, printer).
oCommunication devices: Equipment used to send information and
receive it from one location to another (e.g., modem)
Central Processing Unit (CPU)
Central Processing Unit (CPU): The actual hardware that interprets and
executes the program (software) instructions and coordinates how all the
other hardware devices work together
It contains two primary parts: control unit and arithmetic/logic unit
Control unit: interprets software instructions and literally tells the other
hardware devices what to do, based on software instructions

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Arithmetic/logic unit (ALU): performs all arithmetic operations (for example,
addition and subtraction) and all logic operations ( such as sorting and
comparing numbers)
The number of CPU cycles per second determines how fast a CPU carries out
the software instructions; more cycles per second means faster processing,
and faster CPUs cost more than their slower counterparts. CPU speed is
usually quoted in MHz or GHz
Megahertz (MHz): the number of millions of CPU cycles per second
Gigahertz (GHz): the number of billions of CPU cycles per second
Advances in CPU design
oMost CPUS are Complex instruction set computer (CISC) chips
which is a type of CPU that can recognize as many as 100 or more
instructions, enough to carry out most computations directly
oReduced instruction set computer (RISC) chips: limit the number of
instructions the CPU can execute to increase processing speed
oAn RISC processor runs faster than a CISC processor
oVirtualization: a protected memory space created by the CPU allowing
the computer to create virtual machines
Primary Storage

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Primary Storage: the computer’s main memory, which consists of the random
access memory (RAM), cache memory, and the read-only memory (ROM) that
is directly accessible to the central processing unit (CPU)
Random Access Memory: the computer’s primary working memory, in which
program instructions and data are stored so that they can be accessed
directly by the CPU via the processor’s high-speed external data bus
oMost programs set aside a portion of RAM as a temporary workspace
for data so that one can modify (rewrite) as needed until the data is
ready for printing or storage on secondary storage media, such as a
hard drive or memory key
oVolatility: refers to RAM’s complete loss of stored information if power
is interrupted. RAM is volatile and its contents are lost when the
computer’s electric supply fails
Cache Memory: a small unit of ultra-fast memory that is used to store
recently accessed or frequently accessed data so that CPY does not have to
retrieve this data from slower memory circuits such as RAM.
Read-Only Memory (ROM): the portion of a computer’s primary storage that
does not lose its contents when one switches off the computer
oFlash memory: a special type of rewriteable ROM that is compact and
portable
oMemory cards: contain high-capacity storage that holds data such as
images, music or text files.
oMemory sticks: provide non-volatile memory for a range of portable
devices
Secondary Storage
Secondary storage: equipment designed to store large volumes of data for
long-term storage
They are non-volatile and do not lose their contents when the computer is
turned off.
Examples are Hard disk and CD-Roms
Megabyte(MB): 1 million bytes
Gigabyte (GB): roughly 1 billion bytes
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