Choosing The Ram

RAM is an acronym for Random Access Memory that is also known as volatile memory, because the data it holds is lost when the desktop PC or laptop/notebook computer using it is switched off. Briefly, RAM memory is used by the system to store data in the form of files for processing by a computer's central processing unit (CPU), also known as the processor. The processors used in most PCs are made by Intel and AMD. The processor runs the program and data files according to instructions given to it by the operating system, which, on PCs, is usually a version of Windows, or, to a much lesser extent, a version of Linux

Unless all of the memory slots on a computer's motherboard are already fitted with memory modules, the RAM memory in most desktop and laptops computers can be increased by installing more memory (upgrading the memory). Installing one or more additional memory modules in a desktop or a laptop computer is a simple process that is dealt with at the top of Page 2 of this article.

Some high-speed RAM memory modules come with passive heatsinks fitted to them. These heatsinks can also be purchased. Names for memory cooling devices are heatspreaders, heat spreaders, ramsinks, memory cooling kits, RAM heat sinks, etc. You can find vendors for them by entering these names in the Google search box at the top of this page (with its Web radio button enabled).
source : http://www.pcbuyerbeware.co.uk/RAM.htm

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Multimedia Computer

A multimedia computer is a computer, that is optimized for high multimedia performance, enabling rich multimedia experience.

Early home computers simply lacked the power and storage necessary for true multimedia. The games for these systems, along with the demo scene were able to achieve high sophistication and technical polish using only simple, blocky graphics and digitally-generated sound. The Amiga 1000 from Commodore has been called the first multimedia computer.[1] Its groundbreaking animation, graphics and sound technologies enabled multimedia content to flourish. Famous demos such as the Boing Ball[2] and Juggler[3] showed off the Amiga's abilities. Later the Atari ST series and Apple Macintosh II extended the concept; the Atari integrated a MIDI port and was the first computer under $1000USD to have 1 megabyte of RAM which is a realistic minimum for multimedia content and the Macintosh was the first computer able to display true photorealistic graphics as well as integrating a CD-ROM drive, whose high capacity was essential for delivering multimedia content in the pre-Internet era.

Multimedia capabilities weren't common on IBM PC compatibles until the advent of Windows 3.0 and the MPC standards in the early 1990s. The original PCs were devised as "serious" business machines and colorful graphics and powerful sound abilities weren't a priority. The few games available suffered from slow video hardware, PC speaker sound and limited color palette when compared to its contemporaries. But as PCs penetrated the home market in the late 1980s, a thriving industry arose to equip PCs to take advantage of the latest sound, graphics and animation technologies. Creative's SoundBlaster series of sound cards, as well as video cards from ATi, nVidia and Matrox soon became standard equipment for most PCs sold.

Most PCs today have good multimedia features. They have dual- or single-core CPUs clocked at 3.0 GHz or faster, at least 1GB of RAM, a 128 MB or higher video card and TV Tuner card. Popular graphics cards include Nvidia Gforce or ATI Radeon. The Intel Viiv platform, and Microsoft Windows XP Media Center Edition are some of today's products aimed at multimedia computing.

More recently, high-performance devices have become more compact, and multimedia computer capabilities are found in mobile devices such as the Apple iPhone and Nokia Nseries, featuring DVD-like video quality, megapixel class cameras, fully capable browser, music and video players, podcasting, blogging, as well as e-mail, instant messaging, presence and internet call (VoIP) functionality. Multiradios help to offer broadband wireless connectivity, including for instance WCDMA/HSDPA and WLAN/Wifi. Devices are also increasingly equipped with GPS receivers and maps applications, providing new capabilities for location-aware services. The Nseries devices are also expandable, allowing for the addition of multiple applications and multimedia content.

Source : http://en.wikipedia.org/wiki/Multimedia_computer

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10 things you should know about building a PC from scratch

With an ever-expanding array of barebones kit options, a growing number of PC parts suppliers, and seven new versions of Microsoft's next Windows client coming, many technology professionals may choose to build custom systems from scratch. Doing so offers several advantages, including the ability to tailor components to your needs while controlling costs. This list offers 10 recommendations to review when building a PC from the ground up.

#1: Select the mobo carefully

The motherboard is the most important component you select when building a PC from scratch. Not only does your motherboard choice determine the number and type of ports (parallel, serial, USB, memory card, etc.) a new system possesses, but it also dictates which processor powers the box, the memory (type and speed) that's used, the number and type of disks (IDE, SATA, etc.) supported, and the resulting PC case style (micro, Shuttle, mid-tower, 1U server, etc.), as the motherboard's form factor (ATX, mini-ITX, etc.) typically determines the case that must be used.

Pay particular attention to a motherboard's CPU socket type when reviewing your processor options. The CPU socket type typically dictates the CPU manufacturer (Intel versus AMD) as well as the processor family (Pentium 4, Athlon, Celeron, Sempron, etc.). If you become confused as to which socket is designed for which CPU, Wikipedia maintains a handy listing.

It's also a good idea to review the motherboard's chipset and video port specifications. Chipset type determines maximum RAM configuration (among other elements), while most every contemporary board supports older PCI technology. Newer boards, however, favor PCI-Express slots over AGP for improved video performance.

#2: Review CPU options

While your motherboard choice often determines the processor (AMD Athlon 64-bit and Intel Core Duo are but two examples), you still have a decision to make. That is, how fast should your processor be?

Remember that a CPU boasting additional processor cycles will provide improved performance during its service life, and the service life may well be extended proportionate to its increase in speed over base models. In other words, a Pentium 4 3.06 GHz chip is more likely to meet minimum system requirements longer than the same model CPU with a 2.26 GHz clock.

#3: Don't skimp on the PC case

Avoid the temptation to purchase the cheapest beige box. The case that houses the system does more than just hold the PC's components. Cases also determine the system's footprint, as well as the type and number of data ports easily accessed from the machine's front.

#4: Power up

Never underestimate the importance of a good power supply. Problematic power supplies can be a nightmare to diagnose. Ensure that you purchase a quality unit that generates sufficient power for your system's configuration.

#5: Check the RAM

You can never have enough RAM, but you can certainly purchase it improperly. For example, if you need 2 GB of RAM, don't plan on plugging four 512 MB sticks into most boards. Many motherboards now feature only a pair of RAM slots, so be sure to purchase the most concentrated RAM modules you can.

Also, purchase the correct memory. It's easy to confuse different types. Confirm that you've received the proper RAM and aren't the recipient of 333 MHz DDR memory when you paid for a 400 MHz DDR stick, as almost happened to me recently. (Fortunately, I caught the error and corrected a well-intentioned clerk prior to completing the purchase.)

#6: Choose the right disk format

Your motherboard selection will provide you with several disk options. In addition to the requisite CD/DVD drive, you'll likely have your choice of IDE, SATA, or even SCSI hard disks. If your system will process large amounts of data often, it's worth supplying the new system with a SATA or SCSI drive.

But if the system is to be used for nonintensive applications (likely the case for the majority of corporate systems), cheaper and potentially recyclable IDE hard disks are readily available and will adequately meet your needs. Don't just assume you need the latest and greatest hardware. Significant savings can be had by reusing an existing 5400 RPM 20 GB IDE disk as opposed to purchasing a new 7,200 RPM 300 GB SATA drive.

#7: Consider video requirements

There used to be little call for potent video cards in most corporate environments. Other than graphic artists, CAD designers, professional photographers, and video production houses, few people other than gamers really required video cards packing more than even 64 MB of video RAM.

But that's all changing. The use of rich media is growing exponentially across all professions. The trend is sure to stress a vast number of video cards currently in use, and Windows Vista (with its graphically intensive Glass interface) will push many organizations to using video cards with 256 MB or more RAM.

Video adapter type is another consideration when building a barebones system. PCI- and AGP-based adapters long met most organization's needs. But PCI-Express, with higher speeds resulting from serial interconnects versus the old-style bus, is overtaking AGP (which itself overtook PCI).

Be sure to keep your organization's requirements, and the system's intended use, in mind when specifying the new PC's video parameters. In many cases, a simple embedded video adapter will meet your needs. In others, a separate AGP or PCI-E slot and video adapter with 256 MB nonshared video RAM may be required to accommodate graphically intensive tasks.

#8: Secure everything

More than a few systems have been hastily built and pressed into service. It's easy to overlook fundamentals, especially when projects stack up, but always take the extra time to secure all the components inside a PC.

Ensure all power supply and data cables are directed away from cooling fans, including fans used to cool the CPU, video card, and the case itself. PCs have lots of moving parts, so prevent cables from shifting position by connecting them to the case's frame (or even other cables) using zip ties.

Also take time to secure all drives and disks in their bays. Don't rely upon a single screw to hold a hard disk or CD/DVD drive in place; use at least two screws (one to each side) and preferably four (two to a side).

#9: Buy a burner

If 40 is the new 30, a CD/DVD burner is the new floppy. Many PCs no longer even include a floppy disk. Assuming a little extra cost now (for a CD or DVD writing drive) will save you time and trouble in the future.

Sure, everyone believes they'll be able to e-mail or FTP larger files to the appropriate vendor, supplier, or customer, but I've lost count of the number of times I've needed to transfer large files but couldn't access FTP shares due to security or firewall issues and couldn't e-mail the files due to Exchange attachment restrictions.

Add a burner to your barebones PC and you'll also have a secondary method of creating backups, too. The benefits simply outweigh the costs.

#10: Cool is good; heat is bad

PC cases commonly don't include five-dollar case fans. Buy one and install it. Heat's a PC's worst enemy.

Purchase a quality CPU fan, too. Both cheap and expensive models (particularly any that add neon glow) should be avoided. Instead, go with tried-and-true manufacturers that don't make CPU cooling complicated. It's a simple problem with a simple solution.

Also, don't store the system's documentation inside the PC. I recently replaced a failed hard disk in a physician's computer that likely died an early death because the previous administrator placed a plastic bag containing the PC's documentation inside the case. It's a practice I see occasionally. Although it's a good idea in concept (keeping a system's documentation, license, and install CD with the unit), the material obstructs airflow. In this case, it blocked numerous exhaust ports and likely contributed to the hard drive's premature failure.

Source : http://articles.techrepublic.com.com/5100-10878_11-6062218.html

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Integrated Circuit Chips (IC)

Circuits are made up of different electronic components (capacitors, resistors, transistors, etc.) wired together in a manner that performs a specific electronic function. . These components are hooked together on fiberglass boards called circuit boards. You can see the small thin copper or metal lines (wires) on a circuit board that connect the different components together. These are called traces.

If you could find an old 7 or 10-transistor radio from the sixties, you could open it up and see the peanut sized transistors on the circuit board. They looked like little water towers with their 3 legs going down to the circuit board where they were soldered in place. Now, imagine that circuit board and all of its transistors, shrunk down to about the size of your little fingernail and put into a small plastic case for protection. In other words, the entire circuit would be integrated into that one small chip. Hence the name, Integrated Circuit (IC).

With today's technology, these circuits and transistors can be etched into small wafers of silicon and sandwiched into a small plastic package or chip. There are small metal pins coming out of the chip that are connected to the silicon wafer inside with microscopic wiring. The most amazing thing is, today's small integrated circuits now contain millions of transistors, not just 7 or 10. These IC chips are then placed on a circuit board connecting them to other components and IC chips.

One technology for producing ICs is called TTL (Transistor Transistor Logic). These chips are actually more tolerant of ESD (Electrostatic Discharge) and even faster than the newer technology. However, they're also larger, use more electricity or power, and their resistance causes them to run very hot. As computer technology advanced and the number of transistors in the chips increased, heat and power consumption became a huge problem.

TTL ICs are still used in computers today, but the newer CMOS chips (Complimentary Metal-Oxide Semiconductor) have all but replaced them entirely. These chips have a semi-conductive metal oxide layer that allows for less resistance, reducing the power consumption and the generated heat. Unfortunately, the very technology that makes these CMOS chips more efficient also makes them very susceptible to electrostatic discharge.

Source : http://www.pccomputernotes.com/integrated_circuits/ics.htm

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The Bus

The CPU has to be able to send various data values, instructions, and information to all the devices and components inside your computer as well as the different peripherals and devices attached. If you look at the bottom of a motherboard you'll see a whole network of lines or electronic pathways that join the different components together. These electronic pathways are nothing more than tiny wires that carry information, data and different signals throughout the computer between the different components. This network of wires or electronic pathways is called the 'Bus'.

That's not that difficult to comprehend, but you've probably heard mention of the internal bus, the external bus, expansion bus, data bus, memory bus, PCI bus, ISA bus, address bus, control bus,… it really can get quite confusing.

A computer's bus can be divided into two different types, Internal and External.

The Internal Bus connects the different components inside the case: The CPU, system memory, and all other components on the motherboard. It's also referred to as the System Bus.

The External Bus connects the different external devices, peripherals, expansion slots, I/O ports and drive connections to the rest of the computer. In other words, the External Bus allows various devices to be added to the computer. It allows for the expansion of the computer's capabilities. It is generally slower than the system bus. Another name for the External Bus, is the Expansion Bus.

So now we know the bus is just a bunch of tiny wires (traces and electronic pathways). One bunch carries info around to the different components on the motherboard, and another bunch of wires connects these components to the various devices attached to the computer.

What kind of stuff travels on the bus? For one thing, data. Data has to be exchanged between devices. Some of the electronic pathways or wires of the Internal Bus or the External Bus are dedicated to moving data. These dedicated pathways are called the Data Bus.

Data is stored, manipulated and processed in system memory. System memory is like a vast sea of information full of fish (data). Your computer has to move information in and out of memory, and it has to keep track of which data is stored where. The computer knows where all the fishes are, but it has to transmit that information to the CPU and other devices. It has to keep a map of the different address locations in memory, and it has to be able to transmit and describe those memory locations to the other components so that they can access the data stored there. The info used to describe the memory locations travels along the address bus. The size, or width of the address bus directly corresponds to the number of address locations that can be accessed. This simply means that the more memory address locations that a processor can address, the more RAM it has the capability of using. It makes sense, right?

A 286 with a 16 bit address bus can access over 16 million locations, or 16 Mb of RAM. A 386 CPU with a 32 bit address bus can access up to 4 GB of RAM. Of course, at the present time, due to space and cost limitations associated with the average home computer, 4GB of RAM is not practical. But, the address bus could handle it if it wanted to! Another name for the address bus is the memory bus.

Source : http://www.pccomputernotes.com/system_bus/bus01.htm

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Photoshop and Memory

In any Mac, Photoshop uses the two main data storage hardware components- RAM and hard disk

drives- to access temporary and permanent data. The data stored in RAM is accessed very quickly because
there are no moving parts- and it can read and write data at the same time in no particular order. It is the fast-
est part of a computer’s memory system. In contrast, data on the hard drive is accessed more slowly; it is lim-
ited by moving parts which have to travel to different physical locations to find or store the data.

Fortunately, Photoshop tries to do as much work as possible using the installed RAM in the computer-
rather than the hard drive. It thrives on RAM and putting more in your machine can make a big positive differ-
ence with performance.

Both Photoshop and the Mac OSX operating system use space on the hard drive to access permanent
data- in the form of application and image files, and temporary data- in the form of the Photoshop scratch disk
file and sometimes Mac OSX’s “virtual memory” swapfiles. The speed of hard drives has a substantial impact
on Photoshop performance.

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Page Swapping

Image files can vary greatly in size. As they increase in size they require more hard drive space for

storage, and they occupy more RAM when opened. The installed RAM available to both Photoshop and the
Mac OSX operating system can be used up quickly when working with large image files. When all available
RAM is already in use but more is required- Photoshop must actively use the scratch disk as a substitute for
RAM.

Mac OSX always reserves a certain amount of RAM for itself- regardless of other running applications.
But when the amount of RAM Photoshop and Mac OSX are trying to use is more than the total amount of RAM
on the computer, Mac OSX also has to use the hard drive as a substitute for RAM, and it begins to actively
read and write data to it’s “virtual memory” swapfile in order to complete whatever operation is in progress.
This is known as “page-swapping”, and has a negative impact on performance. Under ideal conditions, page-
swapping is infrequent or does not occur. However- sometimes its occurrence is unavoidable- especially when
working with really large images. The best way to minimize the possibility of page-swapping is to install a lot of
RAM. The best way to minimize it’s negative effect when it does occur- use a fast hard drive for the Startup
disk.

In the illustration above, active page-swapping is represented by the second number (to the right of the
slash mark) next to Page ins/outs: In this case- 2474. When no page swapping has occurred between restarts
of the computer, this number is normally 0. Here, all the installed RAM is being used, and more was clearly re-
quired.

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The Reality of RAM

In theory, Photoshop 7 and Photoshop CS can use up to 2GB of RAM before resorting to active scratch

disk usage. In actual practice, 100% "Available RAM" in Photoshop 7 and CS memory preferences varies be-
tween about 1600MB and 1800MB in systems with 2GB or more of RAM. This is because Photoshop 7 or CS
"sees" only the first 2 GB of installed RAM, and- assuming this is the total amount installed in the machine, re-
serves a minimal amount of memory for the Mac OSX operating system.

Both Photoshop CS2 and Photoshop CS3 have larger RAM limits and additional sophisticated features
When used with Mac OS 10.3 or newer and 4GB of installed RAM, CS2 can use more RAM directly for image
data- up to 3072MB. An additional amount of RAM- approximately 600MB- is reserved especially for plug-ins,
filters, actions, and other operations that need large amounts of contiguous memory- bringing the total used
directly by Photoshop to roughly 3.7GB. Both CS2 and CS3 "see" only the first 4GB of installed RAM, and as-
suming this is the total amount in the machine, reserve a minimal amount of memory for the Mac OSX operat-
ing system.


For best performance, provide Photoshop and the Mac OSX operating System with as much RAM as possible.
Adding additional RAM to your machine is an excellent investment; it improves overall system performance
across a wide range of applications by reducing swapfile activity, and it allows Photoshop to keep more image
data in RAM for faster processing and less scratch disk use. Large amounts of installed RAM improve Pho-
toshop performance dramatically.

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Mainboard

The most important thing to remember about the motherboard is that it is a printed circuit board which provides all the connections, pathways and "lines" connecting the different components of the computer to each other - specifically, the Central Processing Unit or CPU, which is where (as its name implies) all the "processing" is going on to everything else.

The CPU or "chip" (the most popular of which is Intel's pentium series) is an assembly of transistors and other devices (Pentium IV has over 4 million transistors) which perform or processes myriad programmed tasks.

The CPU rests in a "socket" on the motherboard which is connected to the other components through the board's printed circuits. The most important connections are to the chipsets - especially the northbridge chipset which is connected to the main computer memory (hard disk and RAM), while the southbridge set is connected to the peripherals - video and audio cards, IDE controllers, etc.

Aside from these, the most important element of the motherboard is the BIOS chip - which performs key functions like checking power supply, the hard disk drive, operating system, etc. before the computer actually starts "booting up". Turning on the computer automatically starts the BIOS chip up to perform its diagnostic functions, after which it powers up the CPU which - in its turn - starts powering up the other peripherals (hard disk, operating system, video and audio, etc.).

This is why the motherboard is the key component of the computer. It is, in effect, the "housing" for the CPU - the place where the latter resides and from which commands, instructions, and power course through before being sent out to other components.

Source : http://wiki.answers.com/Q/FAQ/4320

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RAM (Random Access Memory )

RAM is memory is where the computer stores all the repetitive tasks that it needs to do to keep going. It might sound very simple but you shouldn’t underestimate its importance. Every task your computer performs goes through the RAM and the more you have the more things it can do more quickly.

You computer uses the RAM to organise every task and manage all the data that the processor throws at it. If you don’t have enough RAM then the computer will use hard disk memory to perform its memory tasks. The problem with this is that current disks are slow and the more you use them the higher your risk of damage to the drive. It’s also a much slower way of organising all your data because a hard disk isn’t designed to process memory in the same way as RAM.

Without getting too technical RAM is a series of memory cells that hold a charge of electricity. With the charge each cell represents a 1 and without a 0. The faster the charge can be passed through the faster data can be used. Of course, the larger the cell the more data can be passed through as well. It is possible to get faster RAM and some systems work better with identical sizes of RAM chip installed.

You can upgrade the RAM on all systems so if you’ve got a desktop or laptop computer there’s no problem with you getting more. The most important thing is to check that you’ve got free slots that you can install memory in to. There are loads of websites that can help you determine what kind of RAM you need but if all else fails contact the manufacturer who’ll be able to let you know what chips you need.

The Need for Speed

The more RAM you have the faster your computer will go. It really is a simple as that. There are other limitations of course but basically it’s best to invest in as much RAM as possible. If your computer is a bit old and feeling slow then a RAM upgrade is the simplest way to increase the responsiveness. Most computers are very simple to upgrade but you’ll need to make sure that you get the right stuff.

Not all RAM is the same and even RAM chips that share similar physical characteristics can be incompatible. Make sure you buy as much RAM as you can afford and it can be a much cheaper way of making your computer go much faster. Rather than having to invest in a brand new computer you can breath life into an old machine just by upgrading the RAM.

Source : http://www.technologybasics.co.uk/ComputerCategory.html

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Hard Disk Drive

A hard disk is part of a unit, often called a "disk drive," "hard drive," or "hard disk drive," that stores and provides relatively quick access to large amounts of data on an electromagnetically charged surface or set of surfaces. Today's computers typically come with a hard disk that contains several billion bytes of storages.

A hard disk is really a set of stacked "disks," each of which, like phonograph records, has data recorded electromagnetically in concentric circles or "tracks" on the disk. A "head" (something like a phonograph arm but in a relatively fixed position) records (writes) or reads the information on the tracks. Two heads, one on each side of a disk, read or write the data as the disk spins. Each read or write operation requires that data be located, which is an operation called a "seek." (Data already in a disk change, however, will be located more quickly.)

A hard disk/drive unit comes with a set rotation speed varying from 4500 to 7200 rpm. Disk access time is measured in milliseconds. Although the physical location can be identified with cylinder, track, and sector locations, these are actually mapped to a logical block address that works with the larger address range on today's hard disks.

Source : http://whatis.techtarget.com

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The Way Computer Works

A computer is a device which performs high-speed calculations. It first started with people trying to do quick-and-easy calculations. First came the abacus(most people think it's not a computer). Then came all the giant computers which worked with vacuum tubes (valves). These valves workes as transistors (switches with either turn on and off). On for 1 and off for 0. A computer uses binary language, which stores numbers and strings (words), and other data with only 2 digits (0 and 1)

Now transistors are used, which are much smaller, so quicker computers can be made. Early computers were so slow that some of them was 1/10,000th the speed of a modern day cell-phone.

A computer can only work if it has software (the programs and the system). It is also known as an O/S (Operating System like Apple Macintosh, Microsoft Windows and Linux). If it has software, then it can control all the hardware to do something (like a calculator or a game). When you turn on a computer, data is loaded from the hard drive into the RAM. Then you would login and start running programs. Most programs are interactive (meaning you would input something), so you would need an input device such as a keyboard, mouse or even a scanner. When you click a mouse button or press on a key, the input would go through the wire and into the computer procceser, (the CPU or Central Processing Unit). It would process the input and send a signal to the monitor, so your input would be shown.

Many other things are used in a computer such as -Speakers

- RAM (Random-Access Memory)

-ROM (Read Only memory)

-CD-ROM drive

- ALU (arithmetic logic unit)

- etc

Source : http://wiki.answers.com/Q/How_does_a_computer_work

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CPU

The computer does its primary work in a part of the machine we cannot see, a control center that converts data input to information output. This control center, called the central processing unit (CPU), is a highly complex, extensive set of electronic circuitry that executes stored program instructions. All computers, large and small, must have a central processing unit. As Figure 1 shows, the central processing unit consists of two parts: The control unit and the arithmetic/logic unit. Each part has a specific function.

Before we discuss the control unit and the arithmetic/logic unit in detail, we need to consider data storage and its relationship to the central processing unit. Computers use two types of storage: Primary storage and secondary storage. The CPU interacts closely with primary storage, or main memory, referring to it for both instructions and data. For this reason this part of the reading will discuss memory in the context of the central processing unit. Technically, however, memory is not part of the CPU.

Recall that a computer's memory holds data only temporarily, at the time the computer is executing a program. Secondary storage holds permanent or semi-permanent data on some external magnetic or optical medium. The diskettes and CD-ROM disks that you have seen with personal computers are secondary storage devices, as are hard disks. Since the physical attributes of secondary storage devices determine the way data is organized on them, we will discuss secondary storage and data organization together in another part of our on-line readings.

For more detail on the computer's memory hierarchy, see the How Stuff Works pages on computer memory

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Computer History

Pre-1940

1833: First Semiconductor Effect is Recorded
Michael Faraday describes the “extraordinary case” of his discovery of electrical conduction increasing with temperature in silver sulfide crystals. This is the opposite to that observed in copper and other metals.

1874: Semiconductor Point-Contact Rectifier Effect is Discovered
In the first written description of a semiconductor diode, Ferdinand Braun notes that current flows freely in only one direction at the contact between a metal point and a galena crystal.

1901: Semiconductor Rectifiers Patented as “Cat's Whisker” Detectors
Radio pioneer Jagadis Chandra Bose patents the use of a semiconductor crystal rectifier for detecting radio waves.

1926: Field Effect Semiconductor Device Concepts Patented
Julius Lilienfeld files a patent describing a three-electrode amplifying device based on the semiconducting properties of copper sulfide. Attempts to build such a device continue through the 1930s.

1931: “The Theory Of Electronic Semi-Conductors” is Published
Alan Wilson uses quantum mechanics to explain basic semiconductor properties. Seven years later Boris Davydov (USSR), Nevill Mott (UK), and Walter Schottky (Germany) independently explain rectification.

1940s

1940: Discovery of the p-n Junction
Russell Ohl discovers the p-n junction and photovoltaic effects in silicon that lead to the development of junction transistors and solar cells.

1941: Semiconductor diode rectifiers serve in WW II
Techniques for producing high purity germanium and silicon crystals are developed for wartime radar microwave detectors.

1947: Invention of the Point-Contact Transistor
John Bardeen & Walter Brattain achieve transistor action in a germanium point-contact device in December 1947.

1948: Conception of the Junction Transistor
William Shockley conceives an improved transistor structure based on a theoretical understanding of the p-n junction effect.

1948: The European Transistor Invention
Herbert Mataré & Heinrich Welker independently create a germanium point-contact transistor in France.

1950s

1951: First Grown-Junction Transistors Fabricated
Gordon Teal grows large single crystals of germanium and works with Morgan Sparks to fabricate an n-p-n junction transistor.

1951: Development of Zone Refining
William Pfann and Henry Theurer develop zone refining techniques for production of ultra-pure semiconductor materials.

1952: Bell Labs Licenses Transistor Technology
Bell Labs technology symposia and licensing of transistor patents encourages semiconductor development.

1952: Transistorized Consumer Products Appear
Semiconductors appear in battery-powered hearing aids and pocket radios where consumers are willing to pay a premium for portability and low power consumption.

1953: Transistorized Computers Emerge
A transistorized computer prototype demonstrates the small size and low-power advantages of semiconductors compared to vacuum tubes.

1954: Silicon Transistors Offer Superior Operating Characteristics
Morris Tanenbaum at Bell Labs builds the first silicon transistors but Texas Instruments demonstrates and markets the first commercial devices.

1954: Diffusion Process Developed for Transistors
Following the production of solar cells using high-temperature diffusion methods, Charles Lee and Morris Tanenbaum apply the technique to fabricate high-speed transistors.

1955: Development of Oxide Masking
Carl Frosch and Lincoln Derick grow a silicon dioxide film on wafers to protect their surface and allow controlled diffusion into the underlying silicon.

1955: Photolithography Techniques Are Used to Make Silicon Devices
Jules Andrus and Walter Bond adapt photoengraving techniques from printing technology to enable precise etching of diffusion “windows” in silicon wafers.

1956: Silicon Comes to Silicon Valley
Shockley Semiconductor Laboratory develops Northern California's first prototype silicon devices while training young engineers and scientists for the future Silicon Valley.

1958: Tunnel Diode Promises a High-Speed Semiconductor Switch
Leo Esaki’s novel device is an example of many celebrated semiconductor breakthroughs that do not sustain their early promise as they are overtaken by competing technologies.

1958: Silicon Mesa Transistors Enter Commercial Production
Fairchild Semiconductor produces double-diffused silicon mesa transistors to meet demanding aerospace applications.

1958: Kilby demonstrates a “Solid Circuit”
Jack Kilby produces a microcircuit with both active and passive components fabricated from semiconductor material.

1959: Invention of the “Planar” Manufacturing Process
Jean Hoerni develops the planar process to solve reliability problems of the mesa transistor, thereby revolutionizing semiconductor manufacturing.

1959: Practical Monolithic Integrated Circuit Concept Patented
Robert Noyce builds on Jean Hoerni’s planar process to patent a monolithic integrated circuit structure that can be manufactured in high volume.

1960s

1960: First Planar Integrated Circuit is Fabricated
Jay Last leads development of the first commercial IC based on Hoerni’s planar process and Noyce’s monolithic approach.

1960: Metal Oxide Semiconductor (MOS) Transistor Demonstrated
John Atalla and Dawon Kahng fabricate working transistors and demonstrate the first successful MOS field-effect amplifier.

1960: Epitaxial Deposition Process Enhances Transistor Performance
Development of thin-film crystal-growth process leads to transistors with high switching speeds.

1961: Silicon Transistor Exceeds Germanium Speed
Computer architect Seymour Cray funds development of the first silicon device to meet the performance demands of the world’s fastest machine.

1961: Dedicated Semiconductor Test Equipment Enters Commercial Market
Semiconductor and independent vendors build dedicated test equipment for high-throughput manufacturing.

1962: Apollo Guidance Computer Commits to use ICs
The size, weight, and reduced power consumption of integrated circuits compared to discrete transistor designs justify their higher cost in military and aerospace systems.

1963: Complementary MOS Circuit Configuration is Invented
Frank Wanlass invents the lowest power logic configuration but performance limitations impede early acceptance of today's dominant manufacturing technology.

1963: Standard Logic IC Families introduced
Diode Transistor Logic (DTL) families create a high-volume market for digital ICs but speed, cost, and density advantages establish Transistor Transistor Logic (TTL) as the most popular standard logic configuration by the late 1960s.

1964: Hybrid Microcircuits Reach Peak Production Volumes
Multi-chip SLT packaging technology developed for the IBM System/360 computer family enters mass production.

1964: First Commercial MOS IC Introduced
General Microelectronics uses a Metal-Oxide-Semiconductor (MOS) process to pack more transistors on a chip than bipolar ICs and builds the first calculator chip set using the technology.

1964: The First Widely-Used Analog Integrated Circuit is Introduced
David Talbert and Robert Widlar at Fairchild kick-start a major industry sector by creating commercially successful ICs for analog applications.

1965: “Moore's Law” Predicts the Future of Integrated Circuits
Fairchild’s Director of R & D predicts the rate of increase of transistor density on an integrated circuit and establishes a yardstick for technology progress.

1965: Large Computers Demand Specialty Integrated Circuits
Burroughs and RCA announce the first mainframe computer families based on monolithic integrated circuit technology.

1965: Package is the First to Accommodate System Design Considerations
The Dual In-line Package (DIP) format significantly eases printed circuit board layout and reduces computer assembly cost.

1965: Read-Only-Memory is the First Dedicated IC Memory Configuration
Factory-programmable read-only-memories (ROMs) generate the first integrated circuit random access memory applications.

1966: Semiconductor RAMs Developed for High-Speed Storage
Sixteen-bit bipolar devices are the first ICs designed specifically for high speed read/write memory applications.

1966: Computer Aided Design Tools Developed for ICs
IBM engineers pioneer computer-aided electronic design automation tools for reducing errors and speeding design time.

1967: Turnkey Equipment Suppliers Change Industry Dynamics
Third-party vendors develop specialized knowledge of semiconductor fabrication and emerge as vendors of process technology and turnkey manufacturing facilities.

1967: Application Specific Integrated Circuits employ Computer-Aided Design
Automated design tools reduce the development engineering time to design and deliver complex custom integrated circuits.

1968: Dedicated Current Source IC Integrates a Data Conversion Function
The precision manufacturing requirements of combining analog and digital capability on one chip made them one of the last product areas to yield to monolithic solutions.

1968: Silicon Gate Technology Developed for ICs
Federico Faggin and Tom Klein improve the reliability, packing density, and speed of MOS ICs with a silicon-gate structure. Faggin designs the first commercial silicon-gate IC – the Fairchild 3708.

1969: Schottky-Barrier Diode Doubles the Speed of TTL Memory & Logic
Design innovation enhances speed and lowers power consumption of the industry standard 64-bit TTL RAM architecture. Is quickly applied to new bipolar logic and memory designs.

1970s

1970: MOS Dynamic RAM Competes with Magnetic Core Memory on Price
The Intel i1103 Dynamic RAM (DRAM) presents the first significant semiconductor challenge to magnetic cores as the primary form of computer memory.

1971: Reusable Programmable ROM Introduces Iterative Design Flexibility
Dov Froman’s ultra-violet light erasable ROM design offers an important design tool for the rapid development of microprocessor-based systems, called an erasable, programmable read-only-memory or EPROM.

1971: Microprocessor Condenses CPU Function onto a Single Chip
Intel engineers, led by Federico Faggin, implement Ted Hoff’s architectural concept to create the i4004 single-chip implementation of a computer central processing unit (CPU), now called a micro-processor unit or MPU.

1974: General-Purpose Microcontroller Family is Announced
A single-chip calculator design emerges as the TMS 1000 micro-control unit or MCU, a concept that spawned families of general-purpose digital workhorses that power the tools and toys of the developed world.

1974: Digital Watch is First System-On-Chip Integrated Circuit
The Microma liquid crystal display (LCD) digital watch is the first product to integrate a complete electronic system onto a single silicon chip, called a System-On-Chip or SOC.

1974: Scaling of IC Process Design Rules Quantified
IBM researcher Robert Dennard’s paper on process scaling on MOS memories accelerates a global race to shrink physical dimensions and manufacture ever more complex integrated circuits.

1978: PAL User-Programmable Logic Devices Introduced
John Birkner and H. T. Chua of Monolithic Memories develop easy-to-use programmable array logic (PAL) devices and tools for fast prototyping custom logic functions.

1979: Single Chip Digital Signal Processor Introduced
Bell Labs' single-chip DSP-1 Digital Signal Processor device architecture is optimized for electronic switching systems.

Source : http://www.computerhistory.org/semiconductor/timeline.html

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