About PC

Our PCs are data processors. The PC's function is simple: to process data, and the processing is done electronically inside the CPU and between the other components. That sounds simple, but what is data, and how is it processed electronically in a PC? That is the subject of these paragraf.

About data

Analog dataAnalog data The signals, which we send each other to The signals, which we send each other to

communicate, is communicate, is datadata. Our daily data . Our daily data have many forms: sound, letters, have many forms: sound, letters, numbers, and other characters numbers, and other characters (handwritten or printed), photos, (handwritten or printed), photos, graphics, film. All this data is in its graphics, film. All this data is in its nature analog, which means that it nature analog, which means that it varies in type. In this form, the data-varies in type. In this form, the data-signals are unusable in a PC. The PC can signals are unusable in a PC. The PC can only process concise, simple data only process concise, simple data formats. Such data can be processed formats. Such data can be processed very effectively. very effectively.

Digital dataDigital data

The PC is an electric unit. Therefore, it The PC is an electric unit. Therefore, it can only deal with data, which are can only deal with data, which are associated with electricity. That is associated with electricity. That is accomplished using electric switches, accomplished using electric switches, which are either off or on. You can which are either off or on. You can compare with regular household compare with regular household switches. If the switch is off, the PC switches. If the switch is off, the PC reads numeral 0. If it is on, it is read as reads numeral 0. If it is on, it is read as numeral one. See the illustration below:numeral one. See the illustration below:

With our electric switches, we can write 0 or 1. We can now start our data processing! The PC is filled with these switches (in the form of transistors). Each represents either a 0 or a 1, so we can process data with millions of 0s and 1s.

00 1 bit1 bit

11 1 bit1 bit

01100110 4 bit4 bit

0110101101101011 8 bit8 bit

Bits

Each 0 or 1 is called a bit. Bit is an abbreviation of the expression BInary digiT. It is called binary, since it is derived from the binary number system:

The binary number system is made up of digits, just like our common decimal system (10 digit system). But, while the decimal system uses digits 0 through 9, the binary system only uses digits 0 and 1.

The binary number system

If you are interested in understanding the binary number system, then here is a brief course. See if you can follow the system. See how numbers are constructed in the binary system, using only 0s and 1s:

NumberNumbers, as s, as known known in the in the decimal-decimal-systemsystem

Same Same numbers numbers in binary in binary systemsystem

00 00

11 11

22 1010

33 1111

44 100100

55 101101

66 110110

77 111111

88 10001000

We have seen that the PC appears capable of handling data, if it can receive them as 0s and 1s. This data format is called digital. If we can translate our daily data from their analog format to digital format, they will appear as chains of 0s and 1s, then the PC can handle them. So, we must be able to digitize our data. Pour text, sounds, and pictures into a funnel, from where they emerge as 0s and 1s:

Here's an example of the Binary Code in action: When you type the letter A on your keyboard, electrical signals are sent from the keyboard to the CPU. The CPU turns the signals into binary code. Then, the computer reads the code and sends it on to the monitor to display the letter A.

All these characters must be digitized. They must be expressed in 0s and 1s. Bits are organized in groups of 8. A group of 8 bits is called a byte. 8 bits = 1 byte, that is the system. Then, what can we do with bytes? First, let us see how many different bytes we can construct. A byte is an 8 digit number. We link 0s and 1s in a pattern. How many different ones can we make? Here is one: 01110101, and here is another: 10010101.

We can calculate that you can make 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 different patterns, since each of the 8 bits can have 2 values. (since – так як)

28 (two in the power of eight) is 256. Then there are 256 different bytes! (then - в такому випадку)

Now we assign a byte to each letter and other characters. And since we have 256 patterns to choose from, there is plenty of room for all. Here you see some examples of the "translation:"

CharacCharacterter

Bit Bit patterpatternn

Byte Byte nunumbmberer

CharactCharacterer

Bit Bit patterpatternn

Byte Byte numnumberber

AA 0100000010000011

6565 ¼¼ 1011110101111000

188188

BB 0100001010000100

6666 .. 0010111001011100

4646

CC 0100001010000111

6767 :: 0011101001110100

5858

aa 0110000011000011

9797 $$ 0010010001001000

3636

bb 0110001011000100

9898 \\ 0101110010111000

9292

oo 0110111011011111

111111 ~~ 0111111011111100

126126

pp 0111000011100000

112112 11 0011000001100011

4949

qq 0111000011100011

113113 22 0011001001100100

5050

rr 0111001011100100

114114 99 0011100001110011

5757

xx 0111100011110000

120120 ©© 1010100101010011

169169

yy 0111100011110011

121121 >> 0011111001111100

6262

zz 0111101011110100

122122 ‰‰ 1000100100010011

137137

KB, MB & GBYou may have seen these abbreviations many times before. Do you know what they mean? KB = kilobyte = about 1,000 (one thousand) bytes, (1024 or 2^10) MB = megabyte = about 1,000,000 (one million) bytes, (1,048,576 or 2^20) GB= gigabyte = about 1,000,000,000 (one billion) bytes (1,073,741,824 or 2^30)

ASCIIASCII means American Standard

Code for Information Interchange. It is an industry standard, which assigns letters, numbers, and other characters within the 256 slots available in the 8 bit code.

The ASCII table is divided in 3 sections:

- Non printable system codes between 0 and 31.

- "Lower ASCII" between 32 and 127. This part of the table originates from older, American systems, which worked on 7 bit character tables. Foreign letters, like Ø and Ü were not available then.

- "Higher ASCII" between 128 and 255. This part is programmable, in that you can exchange characters, based on which language you want to write in. Foreign letters are placed in this part.

About text and code

Now we have seen the PCs user data, which are always digitized. But there are many different kinds of data in the PC. You can differentiate between 2 fundamental types of data:

- Program code, which is data, that allows the PC to function. (allow – дозволяти)

- User data, like text, graphics, sound. The fact is, that the CPU must have

instructions to function. We’ll consider about CPU later. An instruction is a string of data, of 0s and 1s.

The CPU is designed to recognize these instructions, which arrive together with the user input data to be processed.

The program code is thus a collection of instructions, which are executed one by one, when the program runs. Each time you click the mouse, or hit a key on the keyboard, instructions are sent from your software (program) to the CPU, telling it what to do next.

User data are those data, which tells the software how to respond. The letters, illustrations, home page/s, etc., which you and I produce, are created with appropriate software.

The PC came out in 1981. In less than 25 years, it has totally changed our means of communicating. When the PC was introduced by IBM, it was just one of many different micro data processors. However, the PC caught on. In 5-7 years, it conquered the market. From being an IBM compatible PC, it became the standard. If we look at early PCs, they are characterized by a number of features. Those were instrumental in creating the PC success.

The PC's success

- The PC was from the start standardized and had an open architecture.

- It was well documented and had great possibilities for expansion.

- It was inexpensive, simple and robust.

The PC started as IBM's baby. It was their design, built over an Intel processor (8088) and fitted to Microsoft's simple operating system MS-DOS.

Since the design was well documented, other companies entered the market. They could produce functionable copies (clones) of the central system software (BIOS). The central ISA bus was not patented. Slowly, a myriad of companies developed, manufacturing IBM compatible PCs and components for them.

The Clone was born. A clone is a copy of a machine. A machine, which can do precisely the same as the original (read IBM). Some of the components (for example the hard disk) may be identical to the original. However, the Clone has another name (Compaq, Olivetti, etc.), or it has no name at all. This is the case with "the real clones." Today, we differentiate between: - Brand names, PCs from IBM, Compaq, AST, etc. Companies which are so big, so they develop their own hardware components. - Clones, which are built from standard components. Anyone can make a clone. Since the basic technology is shared by all PCs.

The von Neumann Model of the PC

Computers have their roots 300 years back in history. Mathematicians and philosophers like Pascal, Leibnitz, Babbage and Boole made the foundation with their theoretical works. Only in the second half of this century was electronic science sufficiently developed to make practical use of their theories.

The modern PC has roots that go back to the USA in the 1940s. Among the many scientists, One of them was John von Neumann (1903-57). He was a mathematician, born in Hungary. We can still use his computer design today. He broke computer hardware down in five primary parts: (still – до цього часу)- CPU - Input - Output - Working memory - Permanent memory Actually, von Neumann was the first to design a computer with a working memory (what we today call RAM). If we apply his model to current PCs, it will look like this:

The PC constructionThe PC consists of a central unit (referred to as the compu-ter) and various peripherals. The computer is a box, which contains most of the working electronics. It is connected with cables to the peripherals.Here is a list of the PC components.

Components in the central unit Components in the central unit - the computer- the computer PeripheralsPeripherals

The motherboard: CPU, RAM, The motherboard: CPU, RAM, cache, cache, ROM chips with BIOS and ROM chips with BIOS and start-up programs. start-up programs. Chip sets. Ports, buses and Chip sets. Ports, buses and expansion slots. expansion slots. Drives: Hard disk(s), floppy Drives: Hard disk(s), floppy drive(s), CD-ROM, etc. drive(s), CD-ROM, etc. Expansion cards: Graphics Expansion cards: Graphics card (video adapter), card (video adapter), network controller, Sound network controller, Sound card, video and TV card. card, video and TV card. Internal modem.Internal modem.

Keyboard Keyboard and mouse. and mouse. JoystickJoystick, , Monitor Monitor PrinterPrinter, , Scanner Scanner LoudspeakeLoudspeakers rs External External drives drives External External tape station tape station

External External modemmodem

I will show you the computer and its components. Here is a picture of the

computer

Computer’s CaseComputer's case plays a large part in the overall expandability, protection, cooling and lifetime of your system.ExpandabilityAt one time or another you may decide to add something to your computer. Maybe a CD Player, Zip Drive, a second Hard Drive, Floppy or Tape Drive.

These fit on shelves in your computer called Bays. If there are no extra bays, then there’s no place for these devices to go. These bays can be 3.5 inches or 5.25 inches wide. There are internal and external bays. You  can notice the external bays by looking at the front of your case.

Devices like floppy drives and CD-ROMs slide into external bays and can be seen (and accessed) from the front of your system case.

If you have unused bays, they will have a plastic faceplate over them. If you see that you have empty external bays, then you know that at least there's room to add another of this type of device. Remember however, that hard drives are sometimes hidden behind these faceplates, so a look inside the case will tell you for sure. Hard drives are generally situated in internal bays because there is no need for physical outside access. You must look inside the case to see if you have any free internal expansion bays.

Any device added to your system requires power, and your power supply has to have enough juice to supply that power. If you have a 150 or 200-watt power supply, your system may be limited to the amount of devices that can be added.

ProtectionA good, rigid, well built case can protect the internal components from dust, vibration, foreign objects.

Longevity (довговічність) Heat shortens the life of electronic

components. Air flow is needed to cool down the components and devices inside the case. The case fan is the primary source of cooling for your computer.

Although the importance of the fan is often overlooked, it is the key to a long life for your computer. Most computer cases are designed to allow a person to add one or more additional fans. It’s important not to interrupt this flow. Don’t pack things around the case or obstruct the intake vents. Keep the intake vents clean and clear of grime and dust balls. Also, by leaving the expansion slot inserts off the back of the case, or the faceplate off unused external bays, you could possibly be changing the way the air flows through your case and reducing cooling efficiency.

Computer case has multiple functions. It houses all the various components that make up your computer, and it usually comes with the power supply that supplies electricity to your computer system. Cases are offered in two styles, desktop and tower

Inside the case are various regions that perform different functions. The Power Supply which will typically come installed in the computer case supplies power to the computer via various sized Power Connectors and one larger ATX Power Connector.The Motherboard Pan keeps the Motherboard in place using Brass standoffs or plastic connectors. The Full-Height Drive Bay holds the computers CD-ROM, DVD, and CDRW drives.

The Half-Height Drive Bay

contains the computers Floppy Drive, Hard Drive, as well as any other Half-Height devices e.g. Zip drive.The PC Speaker issues various noises that give audio cues to the inner workings of the computer.

Make sure you set the power supply to the proper voltage. 110v in the United States and 220v in other parts of the world. The power supply supplies the fuel (power), for the computer. It supplies power to the motherboard, the drives, and also, normally, contains a fan that helps assist in the task of cooling the computer. Power supplies come in a variety of wattages. 200 watt and 250 watt.

Switches and LEDs

If you look at the front of your case you can see the devices that are installed in the external bays and get an idea as to how many unused bays you have. You will also notice one or more switches and LED lights.

To start your computer, you have to turn on the power supply. At one time, the power switch for your computer was on the power supply itself, and you had to reach around to the back of your computer to turn it on and off. This was inconvenient. Most cases today have a remote power switch on the front of the case. (inconvenient – незручно, troublesome – неспокійний, важкий, remote – віддалений).

Power switch

Reset switch

When you first start your computer, it goes through a series of self-tests (POST - Power-On Self Test) before it actually initializes itself and starts up the operating system. The reset switch performs the same function as a warm boot (ctrl+alt+del) which restarts your computer with an abbreviated version of POST, taking a little time off the startup process. (go through – доводити до кінця, розбирати пункт за пунктом)

Power LED This light tells you when the power is on

to your computer

This light will go on, or flicker, every time your hard drive is written to or read from. It lets you know whenever the hard drive is being accessed.Each device installed in a case’s external drive bay (floppy drive, CD-ROM, tape drive, etc.) will usually have it’s own indicator LED on the front bezel that will come on or flicker when that device is being accessed.

Hard Drive LED

What is a CPU? The CPU is certainly the most important PC

component. CPU stands for Central Processing Unit. Let us briefly study that name:

- It is a processor, because it processes (moves and calculates) data

- It is central, because it is the center of PC data processing.

- It is a unit, because it is a chip, which contains millions of transistors.

Without the CPU, there would be no PC. Like all other hardware components, the CPUs are continually undergoing further development. The CPUs have for years doubled their performance about every 18 months (Moorre’s Law), and there are no indications that this trend will stop.

The CPUs have doubled their calculating capacity every 18 months. This is called "Moore's Law" and was predicted in 1965 by Gordon Moore. He was right for more than 30 years. The latest CPUs use internal wiring only 0.25 microns wide (1/400 of a human hair). But if Moore's Law has to be valid into the next century, more transistors have to be squeezed onto silicon layers.

Moore's Law

IBM succeeded as the first in making copper conductors instead of aluminum. Copper is cheaper and faster, but the problem was to isolate it from the silicon. The problem has been solved with a new type of coating, and now chips can be designed with 0.13 micron technology. The technology is expected later to work with just 0.05 micron wiring!

CPU history starts in 1971, when a small unknown company, Intel, for the first time combined multiple transistors to form a central processing unit - a chip called Intel 4004. However, it was 8 years before the first PC was constructed.

PCs are designed around different CPU generations. Intel is not the only company manufacturing CPUs, but by far the leading one. The following table shows the different CPU generations. They are predominantly Intel chips, but in the 5th generation we see alternatives:

PCPC CPUsCPUs YearYear NumberNumber o of f transistorstransistors

1st. Generation1st. Generation 8086 and 80888086 and 8088 1978-811978-81 29,00029,000

2nd. 2nd. GenerationGeneration

8028680286 19841984 134,000134,000

3rd. Generation3rd. Generation 80386DX and 80386DX and 80386SX80386SX

1987-881987-88 275,000275,000

4th. Generation4th. Generation 80486SX, 80486DX, 80486SX, 80486DX, 80486DX2 and 80486DX2 and

80486DX480486DX4

1990-921990-92 1,200,0001,200,000

5th. Generation5th. Generation Pentium Pentium Cyrix 6X86 Cyrix 6X86 AMD K5 AMD K5

IDT WinChip C6IDT WinChip C6

1993-95 1993-95 1996 1996 1996 1996 19971997

3,100,000 3,100,000 -- -- -- --

3,500,0003,500,000

Improved Improved 5th. Generation5th. Generation

Pentium MMX Pentium MMX IBM/Cyrix 6x86MX IBM/Cyrix 6x86MX IDT WinChip2 3DIDT WinChip2 3D

1997 1997 1997 1997 19981998

4,500,000 4,500,000 6,000,000 6,000,000 6,000,0006,000,000

6th. Generation6th. Generation Pentium Pro Pentium Pro AMD K6 AMD K6

Pentium II Pentium II AMD K6-2AMD K6-2

1995 1995 1997 1997 1997 1997 19981998

5,500,000 5,500,000 8,800,000 8,800,000 7,500,000 7,500,000 9,300,0009,300,000

Improved 6th. Improved 6th. GenerationGeneration

Mobile Pentium II Mobile Pentium II Mobile Celeron Mobile Celeron

Pentium III Pentium III AMD K6-3 AMD K6-3

Pentium III CuMine Pentium III CuMine

1999 1999 27,400,000 27,400,000 18,900,000 18,900,000 9,300,000 9,300,000

? ? 28,000,000 28,000,000

7th. Generation7th. Generation AMD original Athlon AMD original Athlon AMD Athlon AMD Athlon Thunderbird Thunderbird

Pentium 4 Pentium 4

1999 1999 2000 2000 2001 2001

22,000,000 22,000,000 37,000,000 37,000,000 42,000,000 42,000,000

When we now look at all the CPUs from a broader perspective, we can see that: - The CPU history is closely tied to the companies IBM and especially Intel. - The CPUs have their roots back to Intel's chip 4004 from 1971. - You can identify seven or eight CPU generations up till today. - The compatibility concept has been important throughout the development.

How does a CPU work?The CPU is centrally located on the motherboard. Since the CPU carries out a large share of the work in the computer, data pass continually through it. The data come from the RAM and the units (keyboard, drives etc.). After processing, the data is send back to RAM and the units. (carrу out – виконувати, share – доля, частина)The CPU continually receives instructions to be executed. Each instruction is a data processing order. The work itself consists mostly of calculations and data transport:

Data have a path to the CPU. It is kind of a data expressway called the system bus.

Two types of dataThe CPU is fed long streams of data via the system bus. The CPU receives at least two types of data: - Instructions on how to handle the other data. - Data, which must be handled according to the instructions. What we call instructions is program code. That includes those messages, which you continuously send to the PC from the mouse and keyboard. Messages to print, save, open, etc. Data are typically user data. The contents, letters, images, etc., are user data. But if you click "print," you are then sending program code (instructions):

CoolingAll modern CPUs share a common need for cooling. Make sure to include a good cooler. It has to be matched to the size of the CPU.

- It has to be attached properly, either with glue or a clamp, which fits the CPU. - It must have a substantial size heat sink - the bigger the better. - The fan must be mounted in roller bearings, to minimize noise. The bigger the fan and heat sink, the better it is. The CPU will operate more reliably. It will have a longer life span.

What is a cooler?A cooler consists of two parts: - A fan that needs power supply. - A cooling element, usually made of metal ribs. The fan is placed on the top of the cooling element, which is fastened very tight to the top of the CPU:

The power supply can be connected two ways: - From the main power supply of the PC. This is the case in most PCs and all older ones. - From the motherboard. This way the rotation can be monitored by the BIOS software which then can control the temperature of the CPU. This system is implemented on many ATX-boards. Here you see the BIOS program monitoring the temperature (29 C on my board, right now):

Cleaning the coolerAnother important thing to take care of is vacuum cleaning the fan on a regular basis. My old Pentium Pro has a very big fan on it. It began giving error messages within Windows . I really could not find out why. Until I discovered that the heating sink was extremely hot. The fan was rotating as it should, but a large amount of dust had gathered just beneath it, so the air did not cool the sink at all!

Clock frequencyWe know this from the ads: "A Celeron 466 MHz." The 466 MHz is the clock frequency. Actually, there is a small crystal on the motherboard. which continually ticks to the CPU at a steady number of clock ticks per second. At each clock tick something happens in the CPU. Thus, the more ticks per second – the more data are processed per second.

The first CPUs worked at a frequency of 4.77 MHz. Subsequently then, clock frequencies rates rose to 16, 25, 50, 66, 90, 133, 200 MHz, 2GHz ….

Memory (RAM & ROM)These two terms sound very similar and can easily be confused by beginners. However, understanding what they mean and what they do can help you to remember. RAM stands for Random Access Memory. RAM chips will remember what you tell them and can even change to remember new information. But, when the computer is turned off, RAM forgets everything you told it. This is why it is so important to save your work on a computer - if the computer gets turned off, RAM will lose all of your work! ROM stands for Read Only Memory. ROM is good at remembering, but cannot change it's mind. It holds information that is built into it. ROM is like reading a library book - lots of information is there, but you can't change it (because you never write in a library book). RAM, on the other hand, is more like a journal - you can write information into the journal. But if you change your mind, you can erase and write in new information.

MotherboardThe motherboard is kind of like the blood vessels inside the human body which connect to all the vital organs. Instead of blood vessels, the motherboard uses tiny electrical paths to connect each component of the computer. These electrical paths are called "busses." The Chipset (2 chips on this motherboard), manage and directs the flow of data between the components. In the picture of the AOpen AX6B Motherboard above, you can see most of the connecting slots, ports, and connectors. Each is labeled to show which component it connects to.

Data exchange - the motherboardThe ROM chips contain instructions, which are specific for that particular motherboard. Those programs and instructions will remain in the PC throughout its life; usually they are not altered. Primarily the ROM code holds start-up instructions. In fact there are several different programs inside the start-up instructions, but for most users, they are all woven together. You can differentiate between: - POST (Power On Self Test) - The Setup instructions, which connect with the CMOS instructions - BIOS instructions, which connect with the various hardware peripherals - The Boot instructions, which call the operating system (DOS, OS/2, or Windows ) All these instructions are in ROM chips, and they are activated one by one during start-up. Let us look at each part.

All PCs have instructions in ROM chips on the motherboard. The ROM chips are supplied by specialty software manufacturers, who make BIOS chips. The primary suppliers are: - Phoenix - AMI ( American Megatrends ) - Award You can read the name of your BIOS chip during start-up. You can also see the chip on the system board.

Here is an AMI chip with BIOS and start-up instructions:

Here is a picture (slightly blurred) of an Award ROM chip: