1. Basic PC Maintenance, Upgrade and Repair
Computer Overview
Basic PC Maintenance, Upgrade and Repair

2. What is a Computer? A fantastic piece of engineering technology.
An assembly of electronic modules that interact with programs (software) to create, modify, transmit, store, and display data.
Data?
Information
Text
Graphics
Sounds
Data is represented by a digital code.
Digital uses discrete levels (2), whereas analog has unlimited levels.

3. What is a Computer?
Computers range from small microprocessor systems to huge mainframes (and everything in between).
There are essentially two parts to a computer….
Hardware – actual electro-mechanical components.
Software – programs and operating systems.
A computer operates on an electronic principle known as “Digital”
Digital systems use discrete values (on/off).
Computers also must be able to interact with the “Analog” world. This is done through the process of digital-to-analog and analog-to-digital conversion.

4. Role of a Computer Banks Businesses Aircraft Automobiles Television
Communication systems
Home appliances
Satellites
Submarines
And the list goes on and on…….

5. Digital Codes (Data) Computers today use the binary number system.
It consists of two values, “1” and “0”.
These values in a computer are represented electronically as high and low voltages.
These voltages are pulsed (transferred) through a computer system.
This data can be displayed on a computer monitor, or can be stored in memory chips, a hard drive, a floppy disk, or compact disk (CD).
Combinations of 0’s and 1’s represent words, pictures, and sounds, as well as commands such as; load file, save file, find file, or activate the disk drives, etc.

6. The Binary Number System
Just like in the decimal system, number positions are weighted.
For example, in the decimal, the weighted positions would be 1, 10, 100, 1000 and so on.
In the binary system, the positions would be 1, 2, 4, 8 and so on.
Notice in the table at right how these combinations of ones and zeros represent the decimal numbers at the right of them.
This table shows only four positions. The number of positions could be very large.
Binary
Decimal
0000
0001 1
0010 2
0011 3
0100 4
0101 5
0110 6
0111 7
1000 8
1001 9
1010 10
1011 11
1100 12
1101 13
1110 14
1111 15

7. Hexadecimal System
The hexadecimal system groups four bits together and represents them as a single letter or number.
It is based on the number base 16.
Because of the large size of binary numbers, developers use the hexadecimal code to save space in computer programs.
For example, if information was being stored in memory at location “16C7AF45”, the binary number equivalent of that would be
“ ”
Binary
Decimal
Hexadecimal
0000
0001 1
0010 2
0011 3
0100 4
0101 5
0110 6
0111 7
1000 8
1001 9
1010 10 A
1011 11 B
1100 12 C
1101 13 D
1110 14 E
1111 15 F

8. Bits, Bytes and Words A “Bit” is a single binary digit (1/0).
A “Byte” is a combination of eight bits ( ) that could be information, an address, or a command.
A “Word” is a combination of bytes. Some words may contain as many as eight bytes (64 bits)

9. Serial and Parallel Data Transfer
Data is transmitted (clocked, transferred) between two points in a computer or peripheral in two possible ways: Serial and Parallel
Serial data transfer is accomplished by sending the data (words) one bit at a time over a single conductor (wire).

10. Serial and Parallel Data Transfer
Parallel data transfer is accomplished by sending an entire data word (all bits) at the same time over multiple conductors.

11. Numeric equivalent for the base 10 number system
Metric Prefixes
Metric prefixes are commonly used to express the speed and size of computer systems and hardware.
1,000,000,000,000,000,000
Quintillion
260
1018 E
Exa
1,000,000,000,000,000
Quadrillion
250
1015 P
Peta
1,000,000,000,000
Trillion
240
1012 T
Terra
1,000,000,000
Billion
230
109 G
Giga
1,000,000
Million
220
106 M
Mega
1,000
Thousand
210
103 k
Kilo 1
Base
0.001
Thousandth
2-10
10-3 m
Milli
Millionth
2-20
10-6 μ
Micro
Billionth
2-30
10-9 n
Nano
Trillionth
2-40
10-12 p
Pico
Numeric equivalent for the base 10 number system
Common name
Number base 2
Number base 10
Symbol
Metric Name

12. Base 2 and Base 10 Comparisons
The terms used when dealing with computer speeds and memory sizes is actually different than what we think they are.
1,000,000,000,000,000,000
1,152,921,504,606,846,976
Exabyte
1,000,000,000,000,000
1,125,899,906,842,624
Petabyte
1,000,000,000,000
1,099,511,627,776
Terabye
1,000,000,000
1,073,741,824
Gigabyte
1,000,000
1,048,576
Megabyte
1,000
1,024
Kilobyte
Base 10 number system
Base 2 number system
Prefix