Operating Systems (P2, M1)

The Operating System is the interface between user and hardware and so runs the applications on the computer. The OS is also co-ordinates and manages the processes that the computer needs to do along with the resources that need sharing. There are 3 main OS’s and they all offer a varied number of functions and features, these are listed as follows.

Windows 7 – It is the most recent in a line of Microsoft Windows operating systems which have far been the most popular OS’s throughout the computing world and has been since its introduction in 1985. Windows 7 is the most user friendly version of Microsoft Windows as it has many more customizable features that allow the user to access what they wish to more regularly with greater ease.  One reason people stick with Windows is that it is relatively cheap when compared against its main competitors and also has greater compatibility with many software manufactures. Windows 7 also has easier wireless connection software built in to it and many people now used wireless internet in their home and when they are out and about it means that many more people do not find it and issue anymore. Windows 7 contains greater ‘tweaking’ options so if the user wishes to do so they can ‘tweak’ the computer through the OS rather than only in the BIOS. Windows 7 also has a much greater ‘Help centre’ and so many people when they are stuck can find the answers they are looking for from within the OS; and if not than Microsoft also has the biggest customer support services on offer.

·         Windows 7 has greater connection to both WLAN and Wired connections from within the home or outside.

·         It has the greatest customer support of the 3 Operating Systems.

·         It comes with the greatest number of pre-installed software as standard so you do not need to splash out on un-necessary software straight away; or never if you are sensible.

·         Most hardware available is compatible with Windows 7 and if not it will be compatible with a driver update.

·         Has an easier layout than previous Windows Operating Systems so many people have upgraded or gone across to it.

Windows 7 desktop

Linux (Ubuntu 10.10) – Linux has never been the friend of the everyday, home computer user as it is complicated to understand where you are going. However, it has steadily got better and the latest version, 10.10, has a lot better interface to make it more available to people. The major advantage to Linux is the fact that it is free and so for many people when they are building their own computer Linux is the cheapest way to get it running. Another upside to this that it is what is known as ‘open source’. This means that you can get into the bowels of the system and change the code and play about with it. However, not everyone will want to do this, many will want to play games and watch movies; something Linux cannot do well. Linux is a very cheap but very specialist set of Operating Systems as they are highly customizable, to those who know how to do it, but lack many basic functions that Windows and Apple MAC can do.

·         It is highly customizable to the technically literate, but to the average user it is far to complicated.

·         Has some basic programs already installed so you can use it out of the box before you go to the application website through Linux to get other software.

·         It has advanced security software and because it is so rare there are virtually no known viruses for Linux.

·         The wireless connection is not great but you can use a remote log on.

Linux Ubuntu 10.10 Desktop

Snow Leopard X (Apple MAC) – It is the most user friendly and appealing Operating System that is available to buy, but it is a double-edged sword. It is very good at user customizability and the desktop is very nice but it is the most expensive software by a country mile. You can only get the Operating System with Apple products which start at £600 but that is without a monitor so is ‘bare bones’. Snow Leopard X is very popular with people and companies that are in the media industry and so work with photos and video. Although Snow Leopard X is very expensive many people buy them as Apple products are “cool” so many people buy them just because people like the look of them. This means that Snow Leopard has not been made purely for functionality, it has also been made to look good. Snow Leopard X does have good features and comes with ample software pre-installed onto it. Apple also offer a range of there higher priced software at a marked down price if when you buy your computer you choose to pre-install it so the customizability is high before you even turn it on. Microsoft Office is also now available on Snow Leopard X so many people will finally go over to Apple because their company will use Office and they can now take their work at home into work.

·         Great customizability and looks

·         Easy to connect to WLAN or Wired LANs.

·         Very expensive but very fashionable.

·         Comes with a range of high-end software that you are able to buy with the computer or later on.

Snow Leopard X desktop

Motherboards (P1, P2)

Motherboards are arguably the most important piece of equipment within your computer as everything is connected to it or is built on it. The motherboard a PCB, Printed Circuit Board, and so transfers the electrical signals everywhere. There are different form factors of motherboards, these are:

·         ATX – The most commonly used form factor.

·         EATX – This is Extended ATX and so will only fit in certain cases that have been built to accommodate the larger board but it allows greater expansion.

·         Mini or Micro ATX – These are smaller sized boards that are used in Media PC’s and other PCs that need to be smaller than usual.

·         Baby ATX – This is no longer available but was used in legacy IBM machines

Various sizes of motherboard

The reason the motherboard is so important because of all the components it accommodates, these are:

·         CPU slot

o   Holds the CPU and heatsink with fan in place

·         Chipset

o   North and South bridge

o   BIOS chip

·         Memory Slots

o   RAM

§   DDR2 or DDR3

§  The speed of the slot (1000MHz, 1333MHz etc)

o   ROM

·         Voltage Regulator Module

o   This provides the microprocessors with right voltage supply

·         Expansion Slots

o   AGP

o   PCI

o   PCI Express

·         CMOS battery

·         IDE slots

·         SATA slots

·         Power connectors

o   20-24 pin 12V motherboard power connector

o   12VATX connector for the CPU

o   The CPU heatsink fan connector

o   Internal audio

o   Chassis fan connectors

·         Headers

o   USB 2.0

o   Front panel connectors

o   LED light connectors

o   eSATA connectors

o   Case speaker connector

A motherboard

Input and Output Ports (P1, P2)

Input and output ports are found on the back of any computer. These ports are part of the motherboard and have a variety of uses and a variety of ports. The picture below depicts the location and look of many of the ports.

Labeled rear side of a computer

·         The power input is a three pronged plug that is often referred to as the “kettle plug” and connects directly into the PSU. It carries 12V and supplies power to the computer.

·         The PS/2 keyboard and mouse ports are used by the mouse and keyboard to relay what they are doing to the motherboard for the computer to interpret.

·         USB ports are the most widely used form of connection by external devices as it is quick, powered and universal so it can be used in any USB port.

·         The Integrated Serial Port is an old fashioned connection used to dial-up a connection through the modem.

·         The audio ports are the three connections used to connect a speaker or 5.1 surround sound speaker system to the motherboard which will allow music played on the computer to be played through the speakers.

·         S-Video ports are used to produce graphics on a monitor; however it does not produce very good graphics as this connection does not allow high resolution images.

·         DVI ports are a modern video connection used to generate images on a screen and it can produce the highest resolution graphics so it is one of the best connectors around.

·         The Ethernet port on the PCI modem card is used to connect the modem card to the internet and the modem card allows the Ethernet port to connect.

·         PCI USB card is simply a PCI card that allows you to connect more USB devices to your computer than simply the ones on the back of the motherboard.

·         PCI sound card allows you to connect a better specification of speakers to your PC via a faster transfer rate.

·         The VGA port allows the computer to connect to a monitor but as it only sends an analogue signal it is not able to perform as well as the DVI port.

·         Parallel ports allow you to connect external devices, such as printers, to your computer and use them through your PC.

Storage Media (P1, P2)

There are many types of storage media and all of them are used to store data long after the computer has been turned off or if it has been removed from the computer all together. The most common of these storage mediums is the hard drive. The hard drive is a disk that has all the data written to the surface of the disk and is then read by a head that is on a moveable arm; although hard drives nowadays often have more than one platter and more than one head. The hard drive will hold all the information stored to it, such as the operating system, software and any other data, until you either tell it to delete something or until a magnet is passed over the disk; causing the tracks saved on the disk to be erased.

Hard Drive

The hard drives are connected to the motherboard through a cable that is often made of many wires formed into a ribbon. This ribbon is known as an IDE ribbon, Integrated Drive Electronics ribbon. The IDE ribbon is a 40-pin, 80-conductor data cable that connect into the back of the hard drive. The ribbon has two female ends that connect to devices, a master and a slave. The master gets all the information passed to and through it whereas the slave only sees what the master wants it to see. The IDE ribbon connects directly into the motherboard, via a bus, meaning that it is a quick as it can be without the hard drive slotting into the motherboard itself. The newest form of hard drive connection is a Serial ATA, or SATA, connection and is nowhere near as big or flat. It connects to the motherboard, via a bus, like the IDE ribbon, although it is much faster at transferring data as the cable is a high speed cable and the cable is over two pairs of conductors. This is becoming an more popular choice of hard drive connection as it does not have a master and slave so everything is just independent.

SATA Cable

The other types of storage media are:

·         CD – Compact disks (Optical)

·         USB pen drives

·         USB external hard drives – Powered and non-powered

·         SD cards

·         Floppy disks – Legacy (both 3.5” and 5” disks)

External USB hard drive

The USB pens and hard drives are mainly used for portable storage devices as they are smaller than a normal hard drive and you do not need to re-install the hard drive inside the computer every time you change computer. SD cards are often used in cameras as they are the smallest types of storage media but can store enough photos. Floppy disks are rarely found anymore as CDs and DVDs have taken over that corner of the market for saving data to an external disk you can take places and use in other devices.

Memory (P1, P2)

Memory is the most common feature in a computer as it occurs in almost every part. The graphics card has memory, the BIOS is saved on a memory chip but it memory is often over-looked. Memory is found within the CPU in the form of Cache memory which is used for frequently used data and so is used within the CPU as the CPU is constantly obtaining, processing and transporting memory. Cache memory can be both internal, in the CPU, which means it’s primary or external where it is situated on the motherboard, which is known as secondary. Cache is found in levels within the CPU as L1 is situated in the CPU but L2 could be either internal or external. Cache is used in the CPU because it acts as a buffer because it holds the data for the CPU to use. L2 puts the data in the order that the cache guesses the CPU will ask for it due to the previous requests. L1 will guess what the RAM wishes to send to the CPU next.

Cache Memory

There are many different types of memory and they are separated as follows:

·         Volatile

o   DRAM – Dynamic RAM

o   SRAM – Static RAM

·         Non-Volatile

o   ROM

§  PROM

§  EPROM

§  EEPROM

o   Flash

Volatile is the most common used as RAM, Random Access Memory, and it is defined as volatile as when you turn the computer off it is all lost unless you have saved it into a non-volatile form. RAM is commonly found in the form of sticks of memory that are inserted directly onto the motherboard so the interface is much quicker. You can both write to it and read from it so RAM is often used for swapping pieces of information in and out of it; therefore the more RAM you have the less time is spent swapping the information in and out of it. DRAM is the most common form of RAM and is made from capacitors compare to SRAM which uses transistors. SRAM is more expensive and so is often used as cache memory instead as you do not need so much of it.

A stick of RAM

Non-Volatile is ROM, Read Only Memory, and is non-volatile as when the computer is turned off it does not lose the data saved to it. You can sometimes write to it but it is often used for things like storing the BIOS or CMOS. However, because RAM is quicker the BIOS may be copied onto the RAM when booting; this is called shadowing.

BIOS (P1, P2)

The Basic Input/Output System (BIOS) is defined as a, “collection of software utilities that forms part of the operating system”. The BIOS is found in a chip that is attached to the motherboard and is used to configure the hardware that the computer is using and the settings of the various pieces of hardware. The BIOS is also used to:

·         Start up the computer and load the operating system.

·         Check the hardware setting on start up to make sure there are no changes that are problematic.

·         To make sure that all of the components are working together.

·         Check the input and outputs and configure anything if it needs configuring.

BIOS chip on the motherboard

The BIOS also does a POST (Power-On-Self-Test) on all of the hardware components within the system and make sure they are functioning correctly. It also powers on the other BIOS chips that are within the system, on such devices as the graphics cards, as some devices have their own.

During boot up it also checks the CMOS (Complementary Metal Oxide Semiconductor) which is a small battery that is located on the motherboard. It has a tiny 64 byte chip in which it stores all the tome and date and settings for you computer. As mentioned previously, the POST also displays when something is wrong. It normal portrays this through the tiny case speaker being connected to the motherboard and beeps on boot up to show that there is either a missing piece of hardware or one that it suspects to be faulty. It my also show a fault through a flashing LED either on the case or motherboard.

CMOS battery on the motherboard

Finally, you can enter the BIOS on boot up and alter the hardware settings within your computer. You can alter the voltage going to your various devices, the timing of your RAM, speed of your CPU and many other alterations. However, these types of alterations are tampering with the product and so would void any warranty and may also cause your piece of equipment to break due to the added stress.

Expansion Slots and Cards (P1, P2)

Expansion slots are an interface on your motherboard to allow you connect external devices that fit directly to your motherboard rather than through wires which means you get a quicker transfer time. There are many types of expansion slots and there are often many slots on the each motherboard. The first expansion slots was an AGP slot which was a legacy graphics card adapter found on many motherboards, although it is not used on modern motherboards any more. The most common expansion slot is the PCI which can be used for pretty much any purpose, graphics, networking, interface ports etc. The newest slot type, and becoming increasingly common place, is the PCI express slot which is often used for modern graphics cards.

PCI slots on a motherboard

To go into these slots there is an array of expansion cards. Some of these include:

·         Graphics Cards – Used to create the graphics you see on your monitor.

·         Sound Cards – Used to generate the sound coming from your speakers.

·         Network Cards – Used to connect you to the internet.

·         Modems – Used to connect to a phone line for a dial-up connection.

·         TV tuner cards – Used to pick up TV signals and allow you to watch them on your computer.

·         Interface adapter cards – Used to give you extra interface ports, such as USB, eSATA, and firewire.



A graphics card


 

1. To install an expansion card you must first make sure that you are earthed and that the side of your computer has been removed via the two screws at the back.

2. Secondly you must make sure that you make sure you know what expansion slot the card needs to go into, therefore stopping any damage occurring to the equipment.

3. Then you must remove the expansion slot cover that is situated opposite the slot for your card by removing the screw the on top of the cover.

4. Then align the card with the slot and gently push the card into place, making sure it fits and does not bend as you do not wish to damage the card.



Installing the card



5. Once in place you then need to re-place the screw into the case, making sure the card is under the head of the screw as this will hold the card in place when the computer is standing back up.

6. Then re-place the side of the case and turn the computer on and install the drivers necessary.

PSU (Power Supply Unit) (P1, P2)

The power supply unit is the black or silver box, sometimes available in multi-colours, that is in the top of your case that has all the cables coming out of the back of it. The box will often have a fan on it in order for it not to overheat. The box runs on AC/DC power which means that the power is good at both short and long power ranges. The AC/DC is split between internal and external power. The Alternating Current is the external power as that is what is brought in from the plug, which provides 110-115V. Internal is the Direct Current which is needed by various components to be powered and often contains either 5 or 12V of power. It is the PSU that converts the AC into DC to allow the computer to work.

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A multi-coloured PSU



The standard connectors are:

·         P1 – This has 20 or 24 pins and provides the motherboard with power.

·         P4 – ATX12V 4 pin provides power dedicated to the CPU but many modern CPU’s require an EPS12V 8 pin as they need more power.

·         4-pin Peripheral – These go into the various disk drives and case fans and have 2 black wires, ground, 1 red wire, +5V, and 1 yellow wire, +12V.

·         Mini-connector – It is a 4 pin connector and is used to supply power to the floppy drive and can be used as an auxiliary connector for AGP cards.

·         Auxiliary power – There are many types of auxiliary connectors which provide additional power if it is needed.

·         Serial ATA – A 15 pin connector that connects to SATA devices and operates at 3 different voltages, +3.3V, +5V and +12V

·         6-pin – Mainly used for PCI express graphics cards that require additional power.

·         6-pin + 2 – Same as a 6 pin although it has an extra 2 pins in case the card needs more power.

·         C14 IEC connector – Is the 3 pin connector that goes into the back of your PSU and goes into the plug socket.

What the different connectors look like

1. In order for you to be able to remove and replace the PSU you must first make sure that you are earthed and that the side of your computer has been removed via the two screws at the back.

2.Secondly you need to first remove the plug out of the back of the power supply.

3. Then you need to disconnect all of the wires that are connected inside your computer that are connected to your PSU.

4. Then you need to lay the computer on its side and remove the screws holding the PSU to the case.

5. Then the PSU simply comes out, and to replace simply follow the removal instructions in reverse.

The screws you need to remove are located here

Processors (P1, P2)

A processor, or CPU, is the brain of the PC. It performs the general tasks of the computer and co-ordinates the tasks performed by the memory, video card, hard drive and the other storage systems. The CPU is a very complex chip that is made of silicon that fits directly onto the motherboard, or in specialist cases it fits onto a daughterboard that connects to the motherboards via a direct interface.




A CPU chip showing the connection pins.

 

Before the modern CPU’s that are used today their existed a fixed program processor that meant you had to physically change the wires around to perform specific tasks. These were contained in ENIAC computers that were used to compute the “ballistic firing tables”.




An ENIAC in use.

 

The control unit takes all the processes and interprets and directs them to their appropriate locations. The arithmetic/logic unit does exactly what it suggests, it performs all the logic and arithmetic calculations that the computer requires. The memory unit is where the data and instructions are held when the calculations are going on.

A diagram showing the tasks within the processor.

1. To change the processor you must first make sure that you are earthed and that the side of your computer has been removed via the two screws at the back

2. Secondly you must remove the power cable that is allowing power to the processor.

3. The next thing to remove is the heatsink and fan that are situated on top of the processor.

4. You will need to remove the cable going from the fan to the motherboard first and then release the catch to allow the heatsink and fan to come off.

5. Once these are removed you then need to find the release bar which will allow the CPU to be detached from the motherboard.

6. Then simply pull the CPU directly upwards from the slot making sure you do not bend the pins.

7. Then simply place the new CPU back into the slot and complete the tasks to take it out in reverse.

A motherboard with heatsink and fan attached.