Download introduction to information technology - e

Catholic University College of Ghana
Fiapre-Sunyani
HARDWARE
INFORMATION TECHNOLOGY I
Audrey Asante, Faculty of ICST
System Unit
•
• The standard color coding scheme for the
keyboard connector, port, cable is purple
but not all manufacturers follow the color
scheme.
• The standard color coding scheme for the
mouse connecter, port, cable is green.
• PS/2 connections and disconnections can
cause damage to the computer.
USB
• Universal Serial Bus is the new technology
of adding any new peripheral without using
the ps/2 or serial or parallel connection. It
can be plugged and unplugged easily.
PORTS
• Sockets on the outside of the system unit that is
connected to the board on the inside of the
system unit. It allows you to connect a peripheral
device such as a monitor, modem, printer etc
• Types
– Parallel ports are used to connect external devices
that need to send or receive a lot of data over a short
distance. These ports typically send eight bits of data
simultaneously across eight parallel wires. Parallel
ports are mostly used to connect printers to system
units. example is the printer port, scanners, external
storage media. It has 25 pins connector.
PORTS
• Serial ports are used for a wide variety of
purposes. They are used to connect a
mouse, keyboard, modem, and many
other devices to the system unit. Serial
ports send data one bit a time and are
very good for sending information over a
long distance. It comes in two sizes, 9 pins
and 25 pins.
PORTS
• Universal Serial Bus (USB) ports are
expected to gradually replace serial and
parallel ports. They are faster, and one
USB port can be used to connect several
devices to the system unit
PORTS
• FireWire ports are the newest type. They
are even faster than USB ports and are
used to connect high-speed printers and
even video cameras to the system unit.
PORTS
• Accelerated graphics ports (AGP) are
used to connect monitors. They are able to
support high-speed graphics and other
video input.
INSIDE THE SYSTEM UNIT
Motherboard
• It is the main circuit board in the system
unit. It houses the essential components of
the computer. Every component is
connected to the motherboard for the
computer to make use of it.
POWER SUPPLY
• It converts Alternating Current to Direct
Current for the computer to use. The
power supply should be able to supply the
right current for the motherboard to use.
They should match when replacing the
power supply of a computer. All
peripherals and devices are connected to
the power supply to provide the necessary
power. The wires from the power supply
are connected to the various drives.
• It is not healthy for your computer to go off
immediately the light goes off or when
there is not power. You can use a UPS
(uninterruptible power supply) which will
provide the computer with electricity when
the power goes off. You can also use the
surge protector( protect when there is a
surge of high voltage) or voltage regulator
when there is insufficient power.
Access Slots
• They are opening at the back of the
computer to allow devices to be connected
CPU
• Microprocessor processes or manipulates
data into information. If found in any
machine other than the computer, the
microprocessor is called a microcontroller
or embedded computer. It is the brain of
the computer. It is made up of two parts;
CU/ICU and ALU. The components in the
computer system are linked together by
bus.
TYPES OF ALU
• Different types of ALUs are designed to do
arithmetic operations at different speeds.
The faster they work, the more the cost.
• Serial-by-bit ALU: its operation involve a
single pair of bits at a time, one for each
operand. It is a slow process. They are
found in few specialized systems
TYPES OF ALU
• Parallel ALU: It does calculations fast because
for faster calculations, one needs more
transistors in the ALU arithmetic circuits, to
process all of the digits in the operand (all of the
bits in the computer words) simultaneously.
• A word is the number of bits (such as 16, 32 or
64) that can be accessed at one time by the
CPU. The more bits in a word, the more
powerful and the faster the computer is.
CPU
• The system clock can be found in the processor.
• The system clock controls the speed of
operations within a computer. The faster the
clock speed, the faster the computer can
process information.
• Machine Cycle/Fetch-execute-cycle
• A computer speed is measured in MIPS, millions
of instructions per second.
• The processor speed determines how fast the
computer gets things done.
CPU CHIPS
• Most personal computers use two kinds of CPU
chips. Intel-type chips and Motorola-type chips.
• Intel-type chips: developed by Intel corporation
for PCs like IBM, Compaq, Dell, Gateway 2000,
NEC. The higher the number example 486, the
faster the processing speed. Since 1993, new
CPU chips bear the names Pentium, Pentium
Pro, Pentium MMX, Pentium II.
• Motorola-type chips are made by Motorola
for Apple Macintosh computers and its
clones.
ARCHITECTURE OF
MICROPROCESSOR
• CISC: complex instruction set computing is mostly used
in personal computers and in conventional mainframes.
It supports large number of instructions. E.g. are Intel’s
Pentium II and III. It is the most widely used chip design
with thousands of programs written specifically for it.
• RISC: reduced instruction set computing is mainly used
in workstations. It operates with fewer instructions and
RISC-equipped workstations work up to 10 times faster
than conventional computers. It is less costly as
compared to CISC. It is also found in Apple computers
TYPES OF PROCESSING
• Serial: execution of instructions one at a
time
• Parallel: executing more than one
instruction at a time
• Pipelining: this is where the CPU starts a
new instruction as soon as the previous
instruction reaches the next stage of the
machine cycle. Processes speed up.
• The processor speed is affected or determined
by:
• System Clock rate: rate of an electronic pulse
used to synchronize processing. It is measured
in megahertz=I million cycles per second or
gigahertz=I billion cycles per second.
• Bus width = the amount of data the CPU can
transmit at a time to main memory and to input
and output devices.
• Word size = a word is the amount of data
the CPU can process at one time.
• The data are transmitted from registers to
the ALU, and the result of an operation is
transmitted from the ALU to a special
register called an accumulator. It is a
location in the CPU used to hold, or
accumulate the results of ALU operations
Coding Scheme/System
• In order to store and represent text in a
computer, a scheme must be employed to
convert letters, punctuation marks, and special
characters to binary numbers (0 or 1). Some of
the coding schemes are;
ASCII (used in UNIX and DOS/Windows-based
computers)
EBCDIC (for IBM System 390 main frames)
Unicode (for Windows NT and recent browsers)
BINARY CODED DECIMAL (BCD)
• It uses a 4-bit code to represent a decimal
digits. Each digit in a decimal number is
converted to a 4-bit binary number. It is
inefficient to use the BCD because you
cannot use 4 bits to represent 10 different
values. 4 bits can represent up to 24 or 16
distinct quantities
BCD
• If you have a decimal number 3752, which
will be in base 10 when converted to 4 bit
BCD, it will be 0011 0111 0101 0010
• 4 bit BCD was expanded to 6-bit BCD.
EBCDIC SYSTEM
• Extended Binary Coded Decimal
Interchange Code system is an 8-bit BCD
code that allows 256 (28) possible bit
combination. This code can be used to
represent upper-case and lower-case
letters, decimal digits, punctuation marks,
and special characters.
• An example
Character
A
B
9
EBCDIC
1100 0001
1100 0010
1111 1001
• The 4 leftmost bits are the zone bits, and the 4
rightmost bits are the numeric bits. Unique
combination of zone and numeric bits represent
each character. This code was established by
IBM and is used primarily in IBM mainframe
computers and peripheral devices.
ASCII
• American Standard Code for Information
Interchange is a 7-bit code cooperatively
developed by several computer
manufacturers whose objective was to
produce a standard code for all
computers. It allows 128 different
characters. 7-bit per character. It can
handle English Language, math symbols,
Greek letters but not all characters.
ASCII
• Character
A
B
9
ASCII
100 0001
100 0010
011 1010
• The ASCII is used at least for
microcomputers. The ASCII is 7-bit but a
bit is added to make 8-bit to check for
errors or for error detection.
UNICODE
• It is a subset of the ASCII. It uses 2 bytes
that is 16 bits for each character. It can
handle 65,536 character combination
instead of the 256 character combination
of the ASCII. Even though it handles all
alphabets, characters, people still use
ASCII or 8-bit standard for software
applications and database.
Parity Bit
• It is also called the check bit. It is an extra bit
attached to the end of the byte for purposes of
checking for accuracy. There are two types,
even parity and odd parity. It all depends on the
number of on bits to determine whether it is even
or odd. If the number of on bits is wrong, there
will be an error or an error will occur. You would
not know but the computer will know where the
error is coming from.
• Even parity: 01001000, a zero is added to make
it even because we already have two 1s.
MEMORY
• Random Access Memory is also known as
the primary storage, internal memory or
main memory. It stores data temporal. It is
volatile because it is power dependent.
Data stored on the RAM can be retrieved
easily and fast. It stores currently running
programs and their data. It is used for
shorter access time and higher data flow
speeds. Each byte of the memory has a
unique address.
RAM
• It is found or mounted on a circuit board such as
a SIMM (single inline memory module) or DIMM
(dual inline memory module). SIMM has multiple
RAM chips on one side whiles DIMM has
multiple RAM chips on both sides.
• RAM chips can be added by plugging memoryexpansion card into the motherboard. The more
RAM, the faster the computer operates, and the
better your software performs.
TYPES OF RAM
• DRAM chips (dynamic random access
memory): they are used in
microcomputers because they are less
expensive.
• SRAM chips (static random access
memory): they are faster than DRAM but
more expensive and take up more space
and also use more power.
• EDO RAM Chips: a newer type of DRAM
chip. Extended data out approach
performance of SRAM chips. There is
increased speed by using the EDO RAM
chips because they keep data available for
the CPU while it is starting the next
memory access.
MEMORY
• Properties of the RAM
– Quick access
– Power dependent (losses all information when
there is no power
• Is the size of the RAM essential factor in
terms of the speed of the computer?
ROM
• The ROM is also called the boot loader
because it contains the startup program
• It is involatile because data stored on it
cannot be erased.
• Data or information stored on it is
permanent. It is not power dependent
ADVANTAGES OF ROM
• The information they hold is stored in a
form that persists even in the absence of
power. That is ROMs are nonvolatile
• They generally cost less and work faster
TYPES OF ROM
• Programmable read-only memory
(PROM): the contents of a PROM may be
loaded by the user
• Erasable read only memory (EROM):
Their contents can be changed to correct
errors
• Erasable Programmable read-only
memory (EPROM): Their contents as well
can be changed to correct errors.
CACHE-MEMORY
• Cache-Memory: it is also an auxiliary
memory used to accelerate the read and
write access to the RAM. It is close to the
CPU or found on the CPU to provide short
access times.
EXPANSION BOARDS
• They are circuit boards used to improve the
functionality of the computer. Some of the
following tasks that the expansion board
performs are;
–
–
–
–
–
Addition of sound card
Modems
Video cards
Network cards
Memory expansion cards to allow the addition of a
RAM chip
EXPANSION SLOT
• Sockets on the motherboard into which
one plugs an expansion card.
BAYS
• They are used to add drives to the
computer. Some of the components put in
bays are floppy disk drives, hard disks and
removable drives, CD-ROM drives
CMOS
• Complementary metal-oxide semiconductor
(CMOS) chip provides flexibility and
expandability for a computer system. It contains
essential information that is required every time
the computer system is turned on. The chip
supplies such information as the amount of
RAM, type of keyboard, mouse, monitor, and
disk drives. It is powered by a battery and does
not lose its contents when the power is turned
off. Its contents can be changed to reflect
changes in the computer system such as
increased RAM and new hardware devices.
STORAGE MEDIA
• CD-ROM
– What is the difference between CD-Write and
CD-Rewriter?
STORAGE DEVICES
• Six factor to distinguish secondary storage
devices
– Storage capacity
– Access speed (average time needed to locate data on
a secondary-storage device). Measured in millisecond
(thousandths of a second)
– Transfer rate(speed at which data is transferred from
secondary storage to main memory) measured in
megabytes per second.
– Size (portability)
– Removability
– cost
HARD DISK
• They have short access time and have
large capacities.
• The usage of a jumper can make a hard
disk a master or slave.
• Disadvantage
– Possible head crash
HARD DISKS
• Hard disks are connected to the mother
board using the technologies EIDE
(Enhanced integrated drive electronics) in
most computers but we also have the
SCSI (small computer system interface).
In the EIDE technology, ribbon cables are
used to connect. In the SCSI, linkage of
devices onto a single expansion board.
HARD DISK
• Virtual memory is the hard disk space
used to expand RAM when its space is
limited
BUS LINES
• Electrical pathway through which bits are
transmitted within the CPU and between
the CPU and other devices in the system
unit. Types are the address bus, control
bus, data bus
– Expansion bus: carries data between RAM
and the expansion slots
– Local bus connects the expansion slots
directly to the CPU
BUS LINES
• The system unit has more than one type of bus
line. The three principal bus lines or
architectures are
– Industry standard architecture (ISA) was developed
for the IBM personal computer. First it was an 8-bit
wide data path, then it was 16-bits wide. Although too
slow for many of today’s applications, the ISA bus is
still widely used.
– Peripheral component interconnect (PCI) was
originally developed to meet the video demands of
graphical user interfaces. PCI is a high speed 32-bit
or 64-bit bus that is over 20 times faster than ISA
buses. It is widely used to connect the CPU, memory
and expansion boards.
BUS LINES
– Accelerated Graphics Port (AGP) is the
newest bus and over twice as fast as the PCI
bus. While the PCI bus is used for a variety of
purposes, the AGP bus is dedicated to the
acceleration of graphics performance. Widely
used for graphics and 3-D animations, the
AGP is replacing the PCI bus for the transfer
of video data.
Question
• An 8 bit word bus will be how many times
slower than a 32 bit word bus?
PRINTERS
• Dot- Matrix printer: it makes use of pins
which hammers letters on the paper.
Advantages: cheap or inexpensive, carbon
copies are possible.
Disadvantages: noisy, slow to medium
quality, slow to medium speed, colour
fades over time, limited fonts
INKJET
• It makes use of small four nozzles that spray the
ink onto the paper. It makes use of cartridge.
Advantages: high printing quality, low noise,
prints color, less expensive than color laser
printers.
Disadvantages: they are slower as compared to
the laser printers because it can print 35-400
cps (character per second) whiles the laser print
8-200 ppm (pages per minute).
LASER PRINTER
• Its printing system is like the photo copier,
it makes use of laser beam and also a
toner.
• Advantages: low noise, excellent quality,
high speed
• Disadvantage: expensive especially for
colors.
LASER PRINTER
• There are two categories.
– Personal laser printers are inexpensive and
used by many single users. They typically can
print four to six pages a minute.
– Shared laser printers are more expensive and
are used (shared) by a group of users. They
can typically print over 30 pages a minute.
MONITORS
• Two important characteristics of monitors are
size and clarity. A monitor’s size is indicated by
the diagonal length of its viewing area. Common
sizes are 15, 17, 19, and 21 inches. Larger
monitors have the advantage of displaying more
information at one time; however, they are more
expensive.
• A monitor’s clarity is indicated by its resolution,
which is measured in pixels. A pixel are
individual dots or “picture elements” that form
images on a monitor
MONITORS
• For a given size monitor, the greater the
resolution ( the more pixels), the better the
clarity of the image. For a given level of
clarity, larger monitors require a higher
resolution ( more pixels)
• Standards to indicate monitor’s resolution
capabilities are SVGA, XGA, SXGA, and
UXGA
MONITORS
• SVGA stands for Super video graphics array. It has a
minimum resolution of 800 by 600 pixels. It is primarily
used with 15-inch monitors.
• XGA stands for extended graphics array. It has a
resolution of up to 1,024 by 768 pixels. It is a popular
standard today, especially with 17-inch and 19-inch
monitors
• SXGA stands for super extended graphics array. This
standard has a resolution of 1,280 by 1,024 pixels. It is
popular with 19- and 21-inch monitors.
• UXGA stands for ultra extended graphics array. It is the
newest and highest standard. It is used in 21-inch
monitors. UXGA monitors are primarily used for high-end
engineering design and graphic arts.
MONITORS
• Cathode-ray tube (CRT) is the most common
type of monitor for the office and the home. The
primary advantages are low cost and excellent
resolution. The primary disadvantage is the size.
• Flat-Panel Monitors or Liquid crystal display
(LCD) monitors. The technology for this monitor
involves liquid crystals. They are much thinner
than CRTs. There are two types;
MONITORS
– Passive-matrix or dual-scan monitors create
images by scanning the entire screen. This
type requires little power, but the clarity of the
images is not as sharp.
– Active-matrix or thin film transistor (TFT)
monitors do not scan down the screen;
instead, each pixel is independently activated.
More colors with better clarity can be
displayed. They are more expensive and
require more power.