Anatomy of Computer

8/6/2019 Anatomy of Computer

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Anatomy of Computer

Here, I would like to give you a little insight of your computer, So that youcan also brag about your knowladge about hardware to your family and

friends or atleast dont end up looking like an Old-Skool when your kids talkin some lingo like DDR, HD graphics , HDMI etc.

Well.. Here's a pic that might be like yourdesktop ,more or less. I'm sure you must beaware of allthe parts shown here. But just to revise, ( andmake my report look more complete)I'll give ashort introduction.

Moniter- Now this is moniter ( because you canmoniter whats happening inside yoour computerwith it's help) . It is the most common outputdevice which you'll come across. ( By outputdevice, I mean, It shows you some output from the

computer... quite obvious.. huh.. )

CPU- Central Processing Unit. (Now thatsounds something Hi-tech..) All of yourcomputer's work is done inside this box.When we talk about a computer in general,we talk about CPU. Every other component( moniter, keyboard, mouse, priner.. orwhatever...) is to input something or outputsomething from it.

Understand it like this, when youwatch a movie on your computer (Moniter,to be precise), Its because CPU takes inputin form of a file( from DVD ), understandswhat it wants to say(information), andsends signals to your moniter to show that

information(movie). Got that? Good.

Keyboard- Well.. there's not muchto say about this. Keyboard is thereto give some instructions to CPU,


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genrally text or numeric instructions.

Mouse- Honestly, I dont know why its calleda mouse, maybe because it looks like one. Itsused to give directional or positioning co-ordinates to the CPU. We can position tnecurser wherever we want on the screen withits help. With Point and clickmechanism, italso helps us to select any icon or

manipulate its properties.

Okay. So far so good. Now we will look CPU and Moniter with details. EspeciallyCPU, because as i said... thats what computer is.


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Anatomy of CPULets have a look inside CPU.

Pretty much inside that box.. huh..

I'll try to explain you the working of every component and theirsignificance along with a little bit of history and a little insight into future. (and yeah, the good part.. It'll leave you with a lot of cool lingo like ATX,


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SATA etc.) I'll also try to give an account of how the Computer Hardwarecompanies Like HCL align their buisness plans with the evolvingtechnology.

Lets get started.

The Case- The Skeleton of the computer, many people think of it asnothing more than something to bolt thecomponents to keep themprotected. But it provides two very important funtions- Airflow and NoiseInsulation.

Airflow is possibly the most important job of a good case. Componentscan get veryhot, and good airflow is needed to get that heat away from thecomponents. Withoutsufficient cooling, they can become less reliable over time and degrade

faster.

The computer case itself also helps in Noise insulation.(i.e. To keep your comuter


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quite.)Computer parts can make a surprising amount of noise (theprocessors heatsink fan and hard drives are themain culprits; discretegraphics cards can be very loud, too), and the case can beinstrumental inmaking sure most of it doesn't reach your ears.

Computer cases comes in various sizes. We can have any of them

according to our requirement.What we generally have, is an MIDI case, wecan also have a small MINI-ITX for a computer that doesnt do more workthan browsing or word editing etc. or a FULL-TOWER case for gamingpurpose etc.


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Expansion Bays, as we saw in the first figure, are of two sizes, 5.25 inchesand 3.5 inches. They are used to accomodate hard disks and optical drives

etc.

Some good brands making cases are Asus, Cooler Master, Antec etc.

Power Supply- The powersupply is probably best describedas being the heart of thecomputer. It provides all of theother components in the computer

with well, power. It's responsiblefor converting AC electricity fromthe mains into the more usable,lower power DC before distributingit to the other components.

The power rating of a powersupply is most often referred to as its wattage. You can usually tell thepower rating of a PSU just by looking at its model number.An example ofpower rating of 550 watt power supply is as follows:


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Motherboard Size:There are many different motherboard sizes, rangingfrom Mobile-ITX (measuring just 60 x 60mm) to WTX (which is a crazy 356x 425mm). Generally ATX or micro-ATX (ATX stands for Advanced

Technology eXtendible, these are the standerd size developed by Intel tocreate a standerd) size are the common ones, but mini-ITX is gainingpopularity.

Difference in sizes account for the upgadability provided by the boards aswell as the number of expansion slots ( for connecting graphics card,sound card etc),IDE ports ( for connecting some old Hard Drives) and SATAports( for connecting new Hard Drives) offered by motherboards.

While ATX is generally Used for general purpose computing. Micro-ATX isgood for a budget PC which do limited stuff, like browsing the net, working

with word document etc, mini-ITX is generally used in netbooks.


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Chipsets in motherboard.- Components which are connected to themotherboard are controlled and connected by the chipset. Thisusually comprises of a northbridge chip and a southbridge chip.Here'sa picture showing the location of the northbridge and southbridge chips:

the chipsets themselves are almost always manufactured by the CPUmanufacturer; that is, an AMD motherboard will almost always have achipset made by AMD themselves, and Intel makes the chipsets for Intelmotherboards.


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The northbridge chip allows the CPU, RAM and Graphics Card(s) (viaPCIExpress lanes) to communicate between each other as well asconnecting with the southbridge.It also works as RAM controller.In somenew systems, RAM controller and PCIExpress is incorporated inMotherboard itself , so Northbridge no longer exists.

The southbridge is responsible for the communication between the othercomponents, external devices, audio and the network with thenorthbridge.


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Main motherboard slots: Slots are provided in the motherboard fordifferent components to fit into it and communicate with each other.Mainmotherboard slots are as follows:

CPU Slot: This is where the processor is installed. All modern CPU socketsuse some form of lever to lock the processor down against themotherboard to ensure that there is a good connection between the pinsand contacts of the motherboard and processor. There are quite a fewcommon socket designs but they all look relatively similar, as you can seein the following figure:

RAM Slot: This is where the computer's memory is installed. Most modernmotherboards have two channels and either two or four slots (one or twofor each channel).(Dual Channel- two 64bit data channels provide Doublememory bandwidth between processer and memory hence decreasing the


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chances of bottleneck due to difference in CPU bus speed and memoryspeed. ( CPU speed is generally much greater than memeory speed and itcant keep up) ( TOM's Hardware detect 5% performance increase b/wsingle and double channel configration))

In the figure, You can see RAM slots being named as DIMM-A2 etc, here,DIMM is a RAM slot standerd, A represents channel number, 1 representsslot number within that channel, quite simple.

Power Connecters slots: These slots are used to insert connecters from,you guessed it... power supply.The 20+4 Pin(Motherboard connecter)and 4+4 Pin(CPU Connecter) connectors are slotted in their individual

slots.. The 4+4 pin socket is always right near the CPU socket. There are afew places where you may find the 20+4 Pin socket, but more often thannot it's right on the edge furthest from the back of the case, near the RAMslots.

Expansion Slot : PCI and PCIExpress slots are present in most of the


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motherboards for graphics card, sound card etc. to be connected to themotherboard.

PCIExpress comes in various lengths and offering various bandwitdths ( i.e.The speed with which motherboard and the component present inPCIExpress slot can communicate). Some of them are PCI1X, PCI4X,

PCI16X.

The interesting thing about the PCI Express slot is that any PCIE device canwork in any PCIE slot as long as it fits. For example, a graphics card with aPCIE 16x connecter can work in a 1x slot if you were to cut out the plasticback of the slot. Likewise, a PCI Express 1x device will work perfectly in a16x slot. The only real difference between the slots is the number of laneswhich the slot has, and therefore the amount of bandwidth between thedevice and the motherboard (that is, the amount of data which can besent between the two at the same time).So while yes, you could use agraphics card in a 1x slot, it probably wouldn't be a very enjoyableexperience.

Connecters: Various connecters are present in motherboard to attachcomponents like hard disk, speakers , moniter and pretty much everythingelse. Connecters are standerdised for various devices according to thebandwidth they provide.

Different connecters include Front panelconnecter( which is used toconnect power and reset buttons as well as LEDs etc. present on chasis),

IDE Connecter (These were main hard disk and optical drive connectersuntill the introduction of SATA connecters), SATA Connecter ( Used insame prospect as IDE connecters but much faster than them, they have


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eventually replaced them), USB Connecters ( Universal serial bus,Theseconnectors are used to add extra external USB ports such as USB ports onthefront panel of the PC, or to connect internal USB devices such asinternal card readers), Firewire Connecters, Front panel Audioconnecters etc.

Following figure shows different connecters in the motherboard:

The I/O Panel: Input Output panel is there to provide external interface inthe chasis of CPU so that we can plu different devices like USB sticks,moniter etc. to them. ( thats right, we generally plug our USB stick in USBslot present in chasis instead of opening CPU and inserting USB inmotherboard)

Following figure will give an overview of different I/O slots present. (You'llhave seen most of them):


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Video connecters are used to connect your monitor (screen) to yourcomputer. You would connect the monitor to your motherboards I/O Panelonly if you dont have a separate graphics card.The three most commonvideo connectors are VGA, DVI and HDMI.

Since HDMI is the latest standerd , I'll discuss it in some more detailshere

HDMIis the new connector for connecting pretty much anything to new,high definition TVs. HDMI is very similar to DVI(The old standerd thatconnects TVs to PCs cameras etc.) , but with one crucial difference; HDMIis also able to carry an audio signal, so both sound and video aretransferred with just one cable. It is a compact audio/video interface fortransmitting uncompressed digital data. ( Uncompressed data meanshigher quality of video and sound, but requires more bandwidth)

HDMI connects digital audio/video sources (such as set-top boxes,DVD

players,HD DVD players,Blu-Ray players,PCs,PlayStation3 and Xbox 360,and AV receivers) to compatible digital audio devices, computer monitors,video projectors, tablet computers, and digital televisions.
http://en.wikipedia.org/wiki/Set-top_boxhttp://en.wikipedia.org/wiki/Xbox_360http://en.wikipedia.org/wiki/AV_receiverhttp://en.wikipedia.org/wiki/Video_projectorhttp://en.wikipedia.org/wiki/Xbox_360http://en.wikipedia.org/wiki/AV_receiverhttp://en.wikipedia.org/wiki/Video_projectorhttp://en.wikipedia.org/wiki/Set-top_box


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HDMI has also evolved over the years. It has many versions now. Here's atable comparing the HDMI versions:


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As we have seen in comparision chart above that as the HDMI is evolving,it is including more type of data to be carried through it (HDMI 1.4 carriesEthternet data with it too),which is a very good example ofstanderdization. It may be possible in future to connect every device witha PC through a single connecter like HDMI or USB.

PS/2 connecters were the standers connecters for mouse and keyboardbefore USB.

USB is called Universal serial bus for nothing, they are used to connectpretty much anything, from Pen drive to USB modem to mouse, Keyborad


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a lot more.

I'll discuss USB in little details here because it has become a veryimportant connecter now a days:

USB is the set of specifications (i.e. Protocols forcommunication, I/P and O/P ports etc.)

developed by Intel, Compaq, DEC, IBM,Microsoft, NEC, Nortel with the goal ofdeveloping a standerd which makes itfundamentally easier to connect externaldevices to PC and making software configerationfor these devices very easy. It is used for

connection, communication and power supply between PC anddevices.

USB allows high-speed, easy connection of peripherals to a PC. When

plugged in, everything configures automatically. USB is the mostsuccessful interconnect in the history of personal computing and hasmigrated into consumer electronics (CE) and mobile products.

SPEED: USB was initially released with the speed of12 mbps in 1995,( even then it was far better than other devices like CD or floppy, if youhave ever burned a DVD you'll know what I'm saying). Currently wiith itslatest standerd USB 3.0 it has got whopping speed of5 gbps today.

USB Versions : Each sucessive version of USB boasts of higher speedand and additional technologies that take them to whole new level. I'lldiscuss some of them:

USB 1.0 : It is basically the first standarddefinition of USB it supports a low speed rateof 1.5 Mbit/s. It is intended primarily to savecost in low-bandwidth human interface devices(HID) such as keyboards, mice, and

joysticks,pendrives.

USB1.1 : USB 1.0 does not allow for extension cables or pass-throughmonitors (due to timing and power limitations). USB1.1 removed theseproblems and introduced speed of 12 mbps.

USB 2.0 : Also known as Hi-speed USB, itintroduced a speed of 480 mbps. But thats notall, USB 2.0 came with a whole lot offunctionalities, some of them are as follows:

USB On-The-Go is a superb feature which was added to USB 2.0, it

allows two USB devices to talk to each other without requiring the servicesof a personal computer (PC). Portable computing devices such ashandhelds, cell phones and digital cameras that connect to the PC as a


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USB peripheral benefit from having additional capability to connect toother USB devices directly. For instance, users can perform functions suchas sending photos from a digital camera to a printer, PDA, cell phone, orsending music files from an MP3 player to another portable player, PDA orcell phone.

Battery Charging Specification adds suppport for dedicatedchargers (power supplies with USB connectors), host chargers (USB hoststhat can act as chargers) and the No Dead Battery provision which allowsdevices to temporarily draw 100 mA current after they have beenattached. If a USB device is connected to dedicated charger, maximumcurrent drawn by the device may be as high as 1.8 A.( which meansstanderd charging options for devices)

USB 3.0 : Also called Superspeed USB ,itboasts a much more higher data transferbandwidth of SuperSpeed (USB 3.0) rate at 5.0Gbit/s. The USB 3.0 specification was releasedby Intel and partners in August 2008. The newconnectors will be backward compatible butthey will include a new wiring system to allowfor full duplex communication. In addition, theUSB 3.0 specification will be optimized for low power and improvedprotocol efficiency.

USB Connecters : Here's a figure showing standerd USB Connecters:

Ehthernet port is the standerd networking port which you use to connectinternet.

Firewire port is used to connect some hard drives or video related fileoperations.

eSATA is a relatively new connector which allows a hard drive in anexternal enclosure to perform and act like an internal drive; in fact, aneSATA connector usually requires sacrificing one of the SATA portsprovided by the motherboards southbridge.

Audio connecters are the ones you use to connect speakers.TRS ports. Well, these are pretty common ports used to connect your


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headphone, MP3 player etc.

Good Brands for motherboard: The two brands which are arguably thehighest quality are Asus and Gigabyte. Other brands which have mixedrecommendations are MSI, DFI and ASRock

The Processer : The CPU (Central Processing Unit) or processor is thebrain of the computer its where all the calculations are carried out.While RAM and hard drives are important, they simply act as storage whiledata manipulation is carried out by the processor.

Some Gaming systems have a saparate GPU (Graphics processer unit)which handles the Graphics for the comuter which is quite a big task and

requires fair amount of processing power.

Her's a picture of intel's i7 980x processer:

Two typical components of a CPU are the arithmetic logic unit (ALU),which performs arithmetic and logical operations, and the control unit(CU), which extracts instructions from memory and decodes and executesthem, calling on the ALU when necessary.

Brief History of CPUs: Early computers had to be physically rewired inorder to perform different tasks, which caused these machines to be called

"fixed-program computers." Since the term "CPU" is generally defined asan (computer program) execution device, the earliest devices that couldrightly be called CPUs came with the advent of the stored-program


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computer.

Here I'll give a brief on development in CPUs from time to time with thehelp of intel Processers released at different times:

Intel developed its first processer which was a 4 bit processer in 1971.

x86Architecture. In 1978 came the first generation of Lagacy 8086(8bit) processer followed by many generations such as 80286(16 bit) 80386( 32 bit) and Pentium I , II , III, 4 etc. ( ya.. Pentium is x86 lagacy. Pentiumprcessers were Superscaler Architecture...we'll come to that soon.).In 2005it came with the its first dual core processer , Pentium D. X86architecture ruled the market quite long .. from 1978 to 2005 ( thatslong....) .

CoreArchitecture In 2006, Intel launched its First Core architecturebased processer, Coresolo .Followed by Core duo( which was a dualcore processer), Core 2 duo, Core 2 quad the same year. Core i7, Core i5,and finally core i3 followed. Now2nd generation of coreprocessers are available too.

Multiple Cores Up until 2004,all processors had just one core,or processing unit. A processorwas made faster by increasingthat cores clock speed. Thedisadvantage to this was thathigher clock speeds generatedmuch more heat, leading tomassive, noisy heatsinks. Iteventually reached the stagewhere it was simply infeasible tokeep increasing the clock speed.

The solution was to create aprocessor with two cores thatis, a single processor with twosmaller, lower speed processingunits which can carry outdifferent instructions. The benefit in this is obvious why force a singleunit harder and harder to do lots of things at once when you can split thework between two slightly less capable units? Many hands make lightwork, as they say.


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The following diagram shows various CPUs developed by Intel and AMD.


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Working of CPU : CPU is incharge of processing data.

When you double click on an icon to run a program, here is what happens:

1.The program, which is stored inside the hard disk drive, is transferred tothe RAM memory. A program is a series of instructions to the CPU.2.The CPU, using a circuit called memory controller, loads the program

data from the RAM memory.3.The data, now inside the CPU, is processed, with the help of instructionsstored inside the ROM.4.What happens next will depend on the program. The CPU could continueto load and executing the program or could do something with theprocessed data, like displaying something on the screen.

This is generally called as Fetch, Decode, Execute.

Things to know about a CPU : The most common thing which you hearabout a CPU is its Clock Speed ( 2.3 GHz processer etc.. Have heard that

before?). Two other important things to know about a CPU is its CacheMemory and FSB Speed(Front Side Bus Speed).

Clock Speed : One of the most common things youll see when lookingat CPU specifications is the processors clock speed, measured in gigahertz(GHz), with 1GHz being equal to 1 billion hertz or cycles per second.Generally, this means that a 1GHz processor is able to carry out 1 billioncalculations every second (But Thats not the case always). As a generalrule of thumb a processor with a higher clock speed is more powerful thanone with a lower clock speed.

So, what is clock anyway? Clock is a signal used to sync things inside thecomputer.

So, what clock has to do with performance? To think that clock andperformance is the same thing is the most common misconception aboutprocessors.

If you compare two completely identical CPUs, the one running at a higherclock rate will be faster. In this case, with a higher clock rate, the time


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between each clock cycle will be shorter, so things are going to beperformed in less time and the performance will be higher. But when youdo compare two different processors, this is not necessarily true.

If you get two processors with different architectures for example, twodifferent manufacturers, like Intel and AMD things inside the CPU are

completely different.

Each instruction takes a certain number of clock cycles to be executed.Lets say that processor A takes seven clock cycles to perform a giveninstruction, and that processor B takes five clock cycles to perform thissame instruction. If they are running at the same clock rate, processor Bwill be faster, because it can process this instruction is less time.

Cache Memory: The Speed of CPU is much faster than the RAM. SinceCPU needs to fetch every instruction from the RAM, this can seriouslyhinder the performance of Computer, hence Cache is used.

This is a place where the most frequently used data is stored so that it isquickly accessible by the processor. Most recent CPUs have at least 2levels of cache (L1 and L2), with newer and more powerful ones having athird level (L3). L1 is the fastest but smallest level of cache, whereas thehigher levels tend to have much higher quantities but are slower (althoughstill faster than accessing the data from the RAM). Most processors splitthe cache up amongst the cores, although some do have a single cache

for all cores to access. In almost all circumstances more cache is better.

Working of Cache When the CPU loads a data from a certain memoryposition, a circuit called memory cache controller loads into the memorycache a whole block of data below the current position that the CPU has

just loaded. Since usually programs flow in a sequential way, the nextmemory position the CPU will request will probably be the positionimmediately below the memory position that it has just loaded. Since thememory cache controller already loaded a lot of data below the firstmemory position read by the CPU, the next data will be inside the memory

cache, so the CPU doesnt need to go outside to grab the data: it is alreadyloaded inside in the memory cache embedded in the CPU, which it canaccess at its internal clock rate ( i.e its own fast speed).

FSB Speed: Front side bus speed is the an external clock, which is usedwhen transferringdata to and from the RAM memory (using the northbridge chip), and a higher internal clock. The more the FSB Speed, themore transfer rate between RAM and CPU will be increasing overallthroughput.


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To give a real example, on a 3.4 GHz Pentium 4 this 3.4 GHz refers to theCPU internal clock, which is obtained multiplying by 17 its 200 MHzexternal clock.

Intel V/S AMD :Well, its a very controversial issue, both of themanufecturers have very devoted followings, Today, Intel's market is farabove AMD's but as people are becoming more knowledgable aboutcomputing stuff, AMD is also gaining popularity... as much i have gainedfrom my Googling about the issue, both have created some excellent andsome devastating products, AMD processers are generally much Cheaperthan Intel's but intel has much far advantage of its much wider reach inmarket and compatibility with other products as motherboard and chipstetc.


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So, whats the main difference between AMD and Intel processors? It usedto be efficiency AMD processors would be just as powerful as Intels whileperforming at lower clock speeds. Intel focused on increasing clock speedswhereas AMD focused on increasing the amount of work done per cycle.

To put it another way, for those looking to upgrade from an older AMD-based system, those looking for a good balance between price andperformance and those who dont mind going without cutting edgetechnology, an AMD-based computer makes the most sense.

On the other hand, for

those where money is noobject or performance isparticularly important, anIntel-based system isprobably a better bet.

Random Access Memory: RAM (short for RandomAccess Memory, or main


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memory), is similar to the short term memory of the computer. Things thecomputer accesses regularly (like frequently used program files) or needsto store temporarily (like something you cut or copy to the clipboard in theoperating system to paste somewhere else) are stored in RAM.

RAM is referred to as random access because anything stored in RAM can

be accessed in the same amount of time, regardless of where its storedon the module. This is opposite to Serial access memory( like tape recordor hard disk)

RAM is an example of volatile memory. This means that all the data storedin RAM is lost when the computer is turned off while data kept on a harddrive (which is a non-volatile form of storage) is kept safe and sound. AlsoRAM is quite costly as compared to hard disk.

Sizes of RAM: Earlier every computer manufecturer provided differentsize of RAM in its computer which meant that perticular type of RAMswould work with perticular type os computers.

The first standerd size RAM were SIMM, which stands for single in-linememory module. This memory board used a 30-pin connector and wasabout 3.5 x .75 inches in size (about 9 x 2 cm).Each SIMM could send 8bits of data at one time, while the system bus could handle 16 bits at atime.hence two RAMs were to be used simultaneously.

With development in speed and bandwidth capability, the industryadopted a new standard in dual in-line memory module (DIMM). With awhopping 168-pin or 184-pin connector

and a size of 5.4 x 1 inch (about 14 x 2.5 cm), DIMMs range in capacityfrom 8 MB to 1 GB per module and can be installed singly instead of inpairs.

Another standard, Rambus in-line memory module (RIMM), iscomparable in size and pin configuration to DIMM but uses a specialmemory bus to greatly increase speed.

Generally Notebooks use RAM based on the small outline dual in-linememory module (SODIMM) configuration. SODIMM cards are small, about2 x 1 inch (5 x 2.5 cm), and have 144 or 200 pins. Capacity ranges from 16MB to 1 GB per module .


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Types of RAM :

The following are some common types of RAM:

SRAM: Static random access memory uses multiple transistors, typicallyfour to six, for each memory cell but doesn't have a capacitor in each cell.It is used primarily for cache

DRAM: Dynamic random access memory has memory cells with apaired transistor and capacitor requiring constant refreshing. Theseinclude FPM DRAM andEDO DRAM.

SDRAM: Synchronous dynamic random access memory takesadvantage of the burst mode concept to greatly improve performance. Itdoes this by staying on the row containing the requested bit and movingrapidly through the columns, reading each bit as it goes. The idea is thatmost of the time the data needed by the CPU will be in sequence. SDRAMis about five percent faster than EDO RAM and is the most common formin desktops today. Maximum transfer rate to L2 cache is approximately528 MBps. It is most generally used RAM.

DDR SDRAM: Double data rate synchronous dynamic RAM is justlike SDRAM except that is has higher bandwidth, meaning greater speed.Maximum transfer rate to L2 cache is approximately 1,064 MBps (for DDRSDRAM 133 MHZ).

RDRAM: Rambus dynamic random access memory is a radicaldeparture from the previous DRAM architecture. Designed by Rambus ,RDRAM uses a Rambus in-line memory module (RIMM), which issimilar in size and pin configuration to a standard DIMM. What makesRDRAM so different is its use of a special high-speed data bus called theRambus channel. RDRAM memory chips work in parallel to achieve a data


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rate of 800 MHz, or 1,600 MBps. Since they operate at such high speeds,they generate much more heat than other types of chips. To help dissipatethe excess heat Rambus chips are fitted with a heat spreader, which lookslike a long thin wafer. Just like there are smaller versions of DIMMs, thereare also SO-RIMMs, designed for notebook computers.

PCMCIA Memory Card: Another self-contained DRAM module fornotebooks, cards of this type are not proprietary and should work with anynotebook computer whose system bus matches the memory card'sconfiguration.

Credit Card Memory: Credit card memory is a proprietary self-containedDRAM memory module that plugs into a special slot for use in notebooks.

Here's a figure showing different types of RAMs.

Things to know about a RAM : There are a few things you must knowabout RAM ( to gain that geek status you are looking for )

DDR : There's quite a buzz about DDR(Double data rate) RAMs today.Surely we do understand that these are the latest RAMs, but doesn't know

much about them . I would try to explain DDRs in simple teminology toyou.

We know that the data transfer between CPU and RAM takes place at FSBclock speed. Earlier RAMs used to transfer data at the rising edge of clockcycle to the CPU, but in DDR RAMs the data is transferred on rising as wellas falling edge of the clock cycle, this is known as Double pumping.Hence a 100 Hz DDR RAM transfers data at approximately the same speedas 200 Hz Non-DDR RAM.

The next generations of DDR RAMs are DDR2 and DDR3. DDR stands for

Double Data Rate, with the number following simply being the generation;that is to say, DDR2 replaced DDR as the standard type of memory around2004. DDR3 in turn became the most common type of memory for new


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computers in late 2009.

Here's a chart showing the comparision between these generations:

Each generation of DDR runs at

different voltages and significantlydifferent speeds;such, newer kinds ofRAM are not backwards compatible(nor can you use older generations ofDDR in newer motherboards). Toprevent this from happening thedifferent generations have notches indifferent locations along the bottom,making it impossible to plug theminto the wrong sockets.

Speed : Each generation of DDR is in general much faster than the last.However, each generation has multiple speeds. the format DDRx-yyyrefers to the data rate measured in MT/s, or MegaTransfer per second (forexample, DDR2-800 means DDR2 memory with a data rate of 800MT/s,which usually has a bandwidth of 6400MB/s)

Either way, you need to make sure that you get a speed which your

motherboard can support.

Voltage :Although this is a minor thing to look for, you also need to makesure that the voltage which the RAM runs at is compatible with yourmotherboard too.

Brands :This is another one of those things where different people swearby different brands. The two manufacturers who tend to be recommendedthe most are Kingston and Corsair. Other brands like Crucial, Hynixand OCZ seem to produce fairly reliable RAM too, but Kingston andCorsair are the two kings of memory.

Anatomy of Computer

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