Introduction to Computer - Idowu A.J. Odeyemi.pdf

Introduction to Computer
Nobletech Computer Institute Idowu A.J. Odeyemi Page 1 of 20
INTRODUCTION TO COMPUTER
What is Computer?
A computer is an electronic device that capable of accepting data in a described input,
processing of the input data within and supply the result (output) of the processing
data in a specified format as information.
Computers are majorly any machines or devices that can perform the three major
roles of; input, process, and output. Examples of Computers
i. Decoder
ii. Transistor Radio
iii. ATM machine
iv. Amplifier Mixer
v. Digital Alarm Clock
vi. Microwave Oven
vii. Television
viii. Hand / Cell Phone
ix. CD Player
x. Gas / Fuel Dispenser
xi. Car Speedometer
xii. Robot
COMPUTER TREE
COMPUTER
HARDWARE SOFTWARE PEOPLEWARE /HUMANWARE
Software Engineers
Input Process Output System Application Test Engineers
System Architects
Keyboard CPU Monitor Operating system Word processing Operators
Mouse Printer Windows / DOS Spreadsheet Online users
Scanner Memory Projector Desktop Publishing
ALU Speakers Database management
Control Unit Multimedia
E-mail software
Accounting
Games etc.

COMPUTER AS ELECTRONIC MACHINE
The forms the data is accepted or produced are in various ways to form simple words
or numbers through the following operations as follows:
INPUT: Computer accept data from outside for processing within.
STORAGE: The computer holds data internally before, during and after processing.
PROCESSING: The Computer performs operation on data it holds within.
OUTPUT: The computer produces data from within for external use.
BASIC ITEMS AND TASKS
1. Data: is a raw fact which can later be transformed into information. E.g. the
number of items sold by business, the names of Computer students a line of
text, the numerical values used in Mathematical formula. It has become
standard practice to treat the word – Data as singular rather than plural. Data =
Datum. And it can be in three forms; Alphabetic, Numeric and Alphanumeric.
2. Program: is a set of instruction that is written in the language of the computer.
The computer is only able to obey a program instruction if the program has first
installed in the computer. This implies that the computer must be able to input
and store programs in addition to data.
3. Information: A distinction is sometimes made between data and information.
When data is converted into more useful or intelligible form then it is said to be
processed into information.
4. Hardware: This is the general term used to describe all the electronic and
mechanical element of the computer together with those devices used with
computer.
5. Software: this is the general term used to describe all the various programs
that may be used on a computer system together with their associated
documentation.
DATA INPUT PROCESS OUTPUT STORAGE
Keyboard System Unit Monitor Hard Disk
Mouse Control Unit Speakers CD/DVD ROM
ALU Printer Flash Disk
Memory SD Card
INPUT PROCESS OUTPUT
½, ¾ 50
/100, 75
/100

HARDWARE, SOFTWARE AND HUMANWARE (USERS)
The main components or parts of computer system can be divided into „Hardware‟ and
„Software‟.
THE HARDWARES
These are the physical components or devices of computer, which hand can touch,
eyes can see make up the visible computer. It can be divided into two: System Unit
(CPU) and the peripherals.
1. The system unit – CPU is responsible for all processing that the computer does
while the peripherals are responsible for feeding data into the system and for
collecting information from the system. The CPU consists of main or primary
storage, Arithmetic and Logical Unit (ALU) and control unit.
i. The main storage is used for storing data to be processed as well as the
instructions for processing them.
ii. The ALU is the unit for arithmetic and logical operation where all
calculations and relational functions are performed.
iii. The Control Unit ensures the smooth operation of other hardware units.
It fetches and interprets instructions and issues commands to the units
responsible for executing the instructions.
MAIN MEMORY
CONTROL UNIT
INPUT UNIT OUTPUT UNIT
ARITHMETIC & LOGIC
UNIT
CENTRAL PROCESSING UNIT
AUXILIARY STORAGE
2. The Peripherals are in three categories: Input devices, Output devices and
Auxiliary storage devices.
(A) INPUT DEVICES
They are used to supply data and instructions to the computer.
 Keyboard
 Mouse
 Scanner
 Microphone
 DVD/CD ROM
 Card reader
 Light pen

1. KEYBOARD: This provides a means of entering data and instructions into the
computer. When typing using the keyboard there is usually a character by
character display on the monitor. It can be cord or cordless. Keyboard comes with
various ports: Serial, PS/2 and Universal Serial Bus (USB).
Types of Keyboard
There are two types of keyboards namely:
i. Enhanced keyboard having 101 keyboard
ii. Standard keyboard having 88 keys or less but basically they perform the
same function.
Keyboard Layouts
The computer keyboards are in form of four (4) main layouts:
i. QWERTY used in English-speaking (Anglophone) countries across Europe and
Africa.
ii. AZERTY, used in French-speaking (Francophone) and Arabic Speaking countries
across Europe, Middle East (Arab) and Africa.
iii. QWERTZ used predominately in central Europe (Germany, Austria, the Czech
Republic, and other nearby nations).
iv. JCUKEN is the default keyboard layout for Russian and Latin Speaking
Countries.
The keyboard layout is divided into five (5) areas:
i. Typing keys
(a) Numeric Keys e.g. 0, 1, ------- 9,
(b). Alphabetic Keys e.g. A, B,-----Z, a, b,-----z,
ii. Computer keys e.g. Tab, Backspace, Shift, Esc, Ctrl, Alt, Window
Key, Cap Lock, Del, Insert, Home, End, Page Up,
Page Down, Num Lock, Scroll Lock, Enter Key,
Space Bar, Print screen, Pause/Break key,
Option key.
iii. Functional Keys e.g. F1, F2, --------------------- F12
iv. Special Keys e.g. ~,`,@,#,$,%,^,&,*,( ), _,-,+,=, {}, [ ], , |,
?,>,<,‟,”,:,;,‟.

COMPUTER KEYS FUNCTION
Enter - Is used for marking the end of a paragraph or
terminate the continuation of a line in order to move
the text cursor to another blank line.
Backspace - Is used for deleting or erasing characters to the left
of the cursor.
Shift - Is used to switch in between the character case i.e.
from lower case (small letters) to upper case (capital
letters). It is also used for typing the top or upper
character of a key with two characters. E.g. %, &, #,
@, !, +, ”, }, {, * etc, it is also used to make an object to
move on its straight line.
Control {Ctrl} - Is combined with other keys to perform pre-defined
operations e.g. Control S perform saving operation etc.
Alt - Is the for performing pre-defined operations by
combining it with other keys e.g. Alt F4 is used for
closing a package or program.
Cursor Control Keys - Are used for moving the text cursor in the direction
of any cursor control key when pressed.
Insert (Ins) - It allows the text to be over write.
Delete {Del} - Is used for erasing character to the right of the
cursor.
Home - Is used for moving the text cursor to the beginning of
a line.
End - Is used for moving the text cursor to the end of a
line of the text.
Page Up - Is used for moving the text cursor one full screen up.
Page Down - Is used for moving the text cursor one full screen
down.
Escape {Esc} - Is used for canceling an operation i.e. it performs the
same function with the cancel button when it is
clicked.
Print Screen - Is used for printing the text or any object display
on the computer monitor.
Scroll Lock - Is used for locking or unlocking computer scroll.
Break or Purse - Is used for breaking continuous operation.

2. MOUSE: This is a pointing (hand control) device rolled on a surface having central
censor movement. There are Three (3) main types of mouse:
(a) Mechanical
(b) Opto-mechanical
(c) Optical
(a) Mechanical Mouse
In 1972, Bill English (builder of Engelbart‟s original mouse) invented the ball mouse,
while working for Xerox PARC. In this, a single mouse was replaced by the external
wheels, which could roll in any direction, known as “ball mouse”.
Mechanical mouse is a device integrated with an internal metal or rubber ball, which
can spin in all directions (left, right, up and down). Thus, the display cursor moves as
the mouse detects the direction. The ball in the mechanical mouse spins when it comes
in contact with surface on which it is placed. It comes in three different ports; Serial,
Ps/2 and Universal Serial Bus (USB). It is often in Cord form. An example of
Mechanical Mouse is Ball Rolling Mouse.
(b) Opto-mechanical: This type of computer mouse is the same as the mechanical
mouse except that it uses optical sensors to the motion of the ball. A mouse pad
should be used under the mouse to run on. This mouse can either be cord or cordless /
wireless. Example is Trackball Mouse.
(c) Optical: This mouse uses a laser for detecting the mouse‟s movement. You don‟t
need a mouse pad but you can use one made for optical mice. Optical mice do not have
any mechanical moving parts. This type responds more quickly and precisely than the
mechanical and opto-mechanical mice. It is of cord and cordless form. Example is
Joystick, G-Stick Mouse, and Optical Mouse.

Note:
Wireless devices use radiofrequency (RF) technology to communicate information to
computer. Since RF devices require two main components: a transmitter and a receiver
that is why wireless mouse also requires it.
3. SCANNER: this works like office copiers, but instead of making a copy on paper,
they take a paper original either art or text and copy it into a file that can be
stored on your PC‟s hard disk.
The four common scanner types are:
i. Flatbed: Are some of the most commonly used scanners as it
has both home and office functions. The way they scan
documents is that a mechanism rolls under the document to
obtain the image.
ii. Sheet-fed: This type of scanner works like a flatbed
scanner except that the image is fed through the scanner
and moves along the beam to be read rather than the beam
moving. This type is not useful for books, but only single
sheets.
iii. Drum scanners: These types of scanners are used
mainly for capturing a picture and producing at a very
high resolution rate. There are only a few companies
that make these scanners, considering the high cost of
producing a scanner such as this. It is considered a a
tremendous upgrade to a regular flatbed scanner.
iv. Handheld / Portable scanner: Are
designed to capture text and other data
while you are on the go. The scanner is
powered by batteries and once you scan
the text, the content is stored on the
portable scanner. Once you get home, you
can transfer the content to a computer.
Transferring to your computer is done by
using a cable or a wireless connection.

OUTPUT PERIPHERAL DEVICES
These are used for obtaining information or result from the computer. Examples are:
 Monitor (VDU)
 Printer
 Projector
 Speaker
1. MONITOR: Visual Display Unit – This shows the result of the processed data
from the central processing unit for users to see.
Types of Printers
There two (2) Main types of Printer:
(a) Monochrome monitors are monitors with one display colour. It is just like
white and black television set.
(b) Colour Monitors are display units with thousands of colours e.g. VGA, SVGA
etc.
Modes of Monitor
Personal Computer monitors come in two different modes, each of which is known by a
three-letter acronym: CRT and LCD.
i. CRT: Stands for Cathode Ray Tube. The traditional,
glass-screen, television-set-like monitor.
ii. LCD: Stands for Liquid Crystal Display. The newer, flatter
style of computer screen.
2. PRINTER: It is a device that is used for producing a hardcopy output (printed
on paper). Printers are categorized into two via;
(a) Impact Printers are printers that form an impression by hitting the head
print making impact on the paper through the ribbon. They physically strike
the ribbon with the print elements (head) to make an impression on the
paper. E.g. Line printer, Daisy wheel printer, Dot Matrix printer etc.
Line Printer Daisy Wheel Printer Dot Matrix Printer

(b) Non-impact Printers: they are rather than hitting the print head to make an
impression operate in a different mechanism. The print signals activate heat, laser or
photographic actions to form the various impressions. It operates like a photocopy
machine. E.g. Ink-Jet printers, Laser jet printers.
STORAGE DEVICES
This is any hardware capable of holding information either temporarily or permanently.
Types of Storage Devices
There are two types of storage devices used with computers: a primary storage
device, such as RAM, and a secondary storage device, like a hard drive. Secondary
storage can be removable, internal, or external storage.
i. Primary Storage Device: Is the main storage or memory, is the area in a
computer in which data is stored for quick access by the computer's processor.
Examples are: Cache – BIOS, Processor, RAM
ii.
iii. Secondary storage device refers to any volatile storage device that is internal
or external to the computer. A secondary storage device is also known as an
auxiliary storage device. Auxiliary storage devices are used for storing
information on a long term basis. E.g. Hard Disk, Magnetic tape, Magnetic disk,
Compact disk and Flash / Pen disk.
Laser-jet Printer Ink-jet Printer

THE AUXILIARY EQUIPMENT
The auxiliary equipment needs by computer are:
 Air conditioner: This is a gadget for controlling,
especially lowering, the temperature and humidity
of an enclosed space.
 Voltage Stabilizer: Is an electrical appliance used to feed
constant voltage current to electrical gadgets like ACs and
computers, and protects them from damage due to voltage.
 Uninterrupted Power Supply (UPS): It is a backup power
supply that works when electrical power to the computer is
interrupted. A small UPS can supply battery power for a few
minutes so files can be saved and the computer can be shut
down properly.
 Wall/Standing/Ceiling Fan: Is a machine using an electric
motor to rotate vanes in order to move air for cooling.
THE SOFTWARE
Software is basically programs. Programs, simply put consist of sequences of
instructions needed to be performed to accomplish a well – defined tasks. It is the
software that enables the hardware to be put into effective use. Computer without a
program can be referred to as an electronic idiot because it can do nothing
constructive or profitable.
Types of Software
There are two main categories of software;
i. The System Software
ii. The Application Software
(A) System Software
This is a software or program that is designed to run a computer's hardware and
application or productivity programs. It is a platform built for other software(s) to
function.
Parts of System Software
The System Software has two parts via;
i. Operating System
ii. Utilities - Computer language Translator

I. Operating System: Is a group of related programs coded by
group of computer programming experts who have a good working
knowledge of the computer art, science and engineering and
technology.
An operating system is an executive manager of all the resources
of computing systems which are;
 Input device
 Output device
 Computer Memory
 Computer data file
 Computer Program file
 Computer User
Categories of operating systems
i. Windows e.g. 3.0, 95, 98, 2000, NT, XP, Vista, 7, 8, 10
ii. Mac OS e.g. Xlion, X Snow Leopard, iOS, Watch, tv, High Sierra
iii. UNIX e.g. BSD, System V, IRIX,Tru64
iv. Linux e.g. Ubuntu, Mint, Arch, Deepin, Fedora, Debian, openSUSE
v. Solaris e.g. Clusters, Oracle VM Server, Oracle Developer Studio
vi. Java e.g. Dev. Kit, Standard Ed, Eclipse, Enterprise Ed, Micro Ed
vii. Android e.g. Donut, Nexus, Cupcake, Éclair, Icecream , Sandwich,
KitKat, Lollipop, Jellybean, Nougat.
Functions of Operating System
1. Provides the Interface between the user and the hardware Means Provides the
interface for Working on the System by the user.
2. Manages all the computer resources attached to the system means all the
resources like Memory and Processor and all the Input - Output Devices are
oversee by it.
3. Controls the all the storage operations means directs how the data or files will
be stored into the computers and how the files will be accessed by the users
4. Treats the process management means all the processes given by the user are
handled by the Operating System.
5. Manages the Memory of the Computer System means allocates the Memory to
the Process and also deallocates the Memory from the Process.
6. It provides booting to the system means provides access of the user to other
application or productivity software or programs.
7. Provides recovery of the system when the system gets damaged means due to
some hardware failure, if doesn‟t work properly, provides recovery system which
corrects the system and also provides the backup facility.

II. Utilities - Program Translator: The computer program translator is a group of
related programs coded by a team of computer programming expert on an agreement
with the manufacturer of the computer. The principal functions are
i. Translation of an application program written in a symbolic computer
language such as BASIC, FORTRAN, PASCAL etc., into a binary language,
ii. Verification and validation of the correctness of the application program.
(B) Application Software or Package
An Application Software is software written by
computer programmer in one of the many
computer languages to carry out its specific
task. Also, it is known as “Productivity or
Integrated Software.”
It is a single task program tailored or
personalized to meet user specific need. The
specific task can be in the form of these
following:
i. Letter,
ii. memo,
iii. Payroll,
iv. Student record,
v. Budget,
vi. Slide Show,
vii. Publication,
viii. Advertisement etc.
Kinds of Application Software
There are Nine (9) main categories applications or productivity software:
1. Word Processing e.g. Ms Word, Open Office Word, Google Doc, etc.
2. Spreadsheet e.g. Ms Excel, Lotus 1-2-3, Supercalc, Open Cal etc.
3. Database Management e.g. Ms Access, My SQL, Oracle Dbase, IBMDb2 etc.
4. Graphic e.g. Coreldraw, Photoshop, PaintShop, Blender etc.
5. Presentation e.g. Ms Powerpoint, Corel Presentation, Impress, etc.
6. Accounting e.g. Peachtree, Quickbook, Ms Dynamic GP, etc.
7. Internet Browsers e.g. Yahoomail, gmail, Explorer, Firefox, Safari, etc.
8. Games e.g. Unity, Android, iOS, MSDOS, Steam, etc.
9. Media e.g. VLC, Real player, iTunes, WM Players, Winamp etc.

CLASSIFICATION OF COMPUTER
COMPUTER BY TYPE
There are three (3) types of computer
1. Analog computer
2. Digital computer
3. Hybrid computer
 Analog Computer: this is the computer that is
using for measuring input which varies to respect
to time. And they directly apply the input to
various devices within the computer system
which perform various functions or operations.
They are used for scientific purpose to measure
the result of an experiment, to stimulate
processing which can be described in terms of
quantity varying according to the known rules
over a length of time and for process control of industrial operation.
 Digital Computer: This is a computer or a machine
capable of performing an operation on data
represented in digital or number form, i.e. the
data is represented as a series of element
arranged in coded form to represent number. In
most digital computer, the method of number
representation is based on binary notation and
each element is the series that is capable of
representing either a bit (binary digit) 0‟s or 1‟s.
 Hybrid Computer: the term „Hybrid‟ refers any
mixed computer system in which both analog and
digital computer devices are combined. In
another words, it can be defined as a computer
that is capable performing both function of
digital and analog computers.

COMPUTER BY SIZE
The computer is classified into three main classes:
1. Mainframe computers,
2. Minicomputers,
3. Microcomputers,
4. Workstation,
5. Supercomputer.
 Mainframe computer: This is extra-large sized computer
and powerful machine used in offices where large
volumes of data are processed. E.g. NCR 8000, IBM 370.
 Minicomputer: This is medium sized of computer. It looks
like file cabinets commonly found in banks, research
centers and so on. E.g. IBM 8100, Honeywell – DPS 6.
 Microcomputer: This is the cheapest and most popular
smallest computer. It is called Personal Computer (PC).
This is because it serves one person at a time. E.g.
Desktop, Laptop, Notebook computers etc. E.g. Radio
Shack, IBM Pc, Apple II Pc, Compaq, Dell etc.
 Workstation: This computer is not common. It is called
super - micro because it is a small powerful PC commonly
used by Scientists and Engineers for drafting and map
making.
 Supercomputer: This is a very expensive computer
that is mainly used in scientific installations like;
Airport and meteorology-weather predictions. E.g.
CRAY 1, CRAY 2

COMPUTER BY PURPOSE
Computer can be classified by purpose into two
i. Special purpose
ii. General purpose
 Special purpose: These are computers designed to carry out specific tasks.
They have in built programs which are stored in a part of the main memory
called Read Only Memory (ROM). The content of this part of the memory can be
accessed and executed by the computer, but he modified by the programmer or
the user.
 General Purpose: These are computers that are not specifically designed or built
for specific jobs. They solve various kinds of problems depending on the
program or software loaded into them. Their content of this part of the
memory is typically Random Access Memory (RAM), a temporary storage that
loses its contents when the computer is switched off. They are commonly found
in business, commercial and scientific environment.

COMPUTER BY AGE OF TECHNOLOGY OR GENERATION
The digital computer derives their names
from the word „digit‟ meaning „figure‟.
Fingers and toes are the first device used
for counting. Stone and pebble replaced
finger and toes for counting anything
(number) greater than twenty.
The Abacus, one of the earlier counting devices was used
about 5000 years ago and it still in use till today for
performing mathematical calculations.
2,000 years ago, Astrolabe is another computer
instrument for navigation.
In 1614, John Napier invented "Napier's bones" used for
logarithms calculation and with the introduction of the decimal
point in arithmetic and mathematics.
1620, William Oughtred invented the slide
rule – a calculating device used to obtain
products, quotients or other functions by
inspection like analog device.
In 1642, Blaise Pascal developed the first adding machine
which was the world first calculator.
Between 1663 and 1666, Sir Moorland in England unaware of Pascal‟s
machine invented three machines out of which only one was used for
British currency addition, pounds and shillings, the other two
machines were used to pre-calculated tables.
Also in 1671, Gottfried Von Leibnitz developed the first
mechanical calculating machine by expanding the function of
Blaise Pascal to include; division and multiplication as well as
addition and subtraction also used to extract square roots.
Between 1802 and 1804, Joseph Jacquard a French textile
manufacturer perfected a mechanical means of automatically
controlling weaving looms to make easy the production of woven cloth
with complex patterns.

1821 was time Charles Babbage developed „a difference Engine‟ but
the machine was never completed because of mechanical difficulties.
However this led to the first developed automatic digital computer
called „Analytical Engine‟. This machine has many features present in
modern computer.
GENERATION OF COMPUTERS
The digital computer has developed at a fast rate with different hardware features.
Each stage of development is associated with one innovation or the other. Each
generation is usually better than the previous.
FIRST GENERATION
Period: mid-forties to mid-fifties (1940‟s – 50‟s)
Components: vacuum tubes, and valves
Mode of operation: processed 5000 basic
operations per seconds
Access time: 500 micro seconds
Speed: slow
Heat generation: a lot of heat and high power consumption
Cost: high
Type: Mainframe – UNIVAC, EDVAC, EDSAC, ASCC (Mark 1).
SECOND GENERATION
Period: late – fifties to early sixties (1950‟s – 60‟s)
Components: semi-conductor devices called
transistors, ferrite core and magnetic disk
Mode of operation: processed 50,000,000 basic
operations per seconds
Access time: a micro seconds
Speed: slow
Heat generation: low range of heat and power consumption
Cost: high
Type: Minicomputer – IBM 7094

THIRD GENERATION
Period: late sixties to seventies (1960‟s – 70‟s)
Components: fabricated integrated circuit (IC) and
large scale integrated circuit or tiny silicon chip (LSIC)
Mode of operation: higher operations per seconds
Access time: higher per seconds
Speed: fast
Heat generation: low range of heat and lower power consumption
Cost: low
Type: Microcomputer – IBM 360
FOURTH GENERATION
Period: seventies to early eighties (1970‟s – 1982)
Components: very large scale integrated circuit
(VLSIC) and micro processor fabricated on a chip
Speed: fast
Heat generation: low heat and low power consumption
Cost: relatively low
Type: Microcomputer – 486 DX
FIFTH GENERATION
Period: early eighties till date (1983 – 1989)
Components: very large scale integrated circuit
(VLSIC), micro processor fabricated on a chip
and some level of artificial intelligence
Speed: fast
Type: Microcomputer – PS/2, USB model, Pentium I – IV, D, M.

SIXTH GENERATION
Period: early eighties till date (1990‟s – 1999)
Components: VLSIC with super-conductors built
on 200 vector processors with artificial
intelligence
Mode of operation: Teraflops i.e. ten arithmetic
operations per second
Speed: fast
Type: Microcomputer – PC Duo Core, Core 2 Quad.
SEVENTH GENERATION
Period: early eighties till date (2000 – Present)
Components: thousands of integrated
circuits built onto a super-conductors
single silicon chip with artificial
intelligence
Mode of operation: Teraflops i.e. ten arithmetic
operations per second
Speed: delivers up to 12% faster processing, and 19%
faster web performance
Type: SuperMicro Computer – PC Corei3, Core i5, Core i7, Robot, CRAY, TITAN etc.
EIGHTIETH GENERATION
The 8th Generation Intel® Core™
processors redefine mainstream
desktop PC performance with up to
six cores for more processing power
- that‟s two more cores than the previous generation
Intel® Core™ processor family i.e., using Turbo Boost
Technology 2.0 to give extra burst of performance
maximum turbo frequency up to 4.7 GHz, and up to 12MB of cache memory. Intel®
Hyper-Threading Technology (Intel® HT Technology) delivers up to 12-way
multitasking support in the latest generation of Intel® Core™ i7-8700K processor
which allows each processor core to work on two tasks at the same time, improving

multitasking, speeding up workflows, and accomplishing more in less time. DDR4 RAM
memory technology support, which allows systems to have up to 64GB of memory and
up to 2666 MT/s memory transfer speeds
NINETH GENERATION
A 9th Generation Intel®
Core™ processor is a great
desktop experience whether
for gaming, creating,
entertainment, or general purpose computing
wherever your life takes you. The 9th Generation
Intel® Core™ i9-9900K processor works with up to
5GHz and 16-way multitasking and this has made it
most powerful generation of Intel® Core™ desktop
processors, with features and enhancements to
evoke excitement in what you love to do.

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