Evaluating a Used Computer

Used computers are available plenty in number. But, the prime concern is that how it will satisfy the needs of the purchaser. The next one is about the functionality of the used computer and the longevity of the computer parts of the used computer. Many people decide to purchase used computers due to a tight budget, but they should not end up buying a showpiece rather than a working piece. This makes it very important to evaluate the used computer before buying it. Evaluation can be done by the purchaser himself provided he has some knowledge on computers and their parts. If not, he can get some help from their friends or relatives who are good in evaluating computers.

The used computer's physical parts should be inspected thoroughly. First step is to look for any damages and then trying to turn on and off. It should be done by the buyer or by his friend rather than watching the computer sales person do it as it will alert for any glitches. Checking needs to be done to find out if the used computer has an original version of the operating software without which the computer is not worth buying. Manuals, licenses for software applications, discs and fonts should be got along with the computer. The operating system of the used computer should be compatible enough to run the required applications of the buyer. Some times the seller may sell a used computer along with used disk drives, scanners and printers and include the cost of them too. It is not wise to buy used scanner, printers or disk drives as they have peripherals with moving parts which wear and tear with the passage of time and also the cost of them can be deducted making the price of the used computer even lesser. <






The speed of the central processing unit needs to be checked. If it is not up to the expectation of the buyer, it needs to be found out if the used computer system can be upgraded for improving the speed and functionality. The entire hardware components should be checked including the keyboard, speakers, monitor, mouse andmicrophones. It should be if all the hardware components inside the computer like the CD-ROM drive, sound card, number of RAM sockets etc are if present or not and if present what are the components in use. Also it needs to be checked whether it has a provision for adding different type of cards etc.

If the purchaser has already got some computer components like the monitor, printer and so on, the used computer which is bought should be compatible with them. Nowadays used Pentium machines and power PCs are available at very low price. It is not advised to buy a used computer which is very old. Also it is good to find out if the used computer comes with a transferable warranty or service, if so it is worth buying.

The buyer should not end up overpaying as used computers depreciate at a lightning speed. There are many online auctions, which can give the idea of how much people are ready to pay for a used computer. Unfortunately, there is no reputed or unbiased source for knowing the prices for used computers.

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Blu-Ray set to take the world by storm!

The Blu-ray Disc belongs to a new generation of optical discs capable of staging high density data. Blu-Ray technology is based on a blue-violet coloured laser. The blue laser operates at a wave length of 405 nm, while older technology such as DVDs and CDs are based on red and infrared lasers that works at 650 and 780 nm. Since the wave length is shorter with a blue laser, the new Blu-ray technology makes is possible to store much more information

The advantage with the Blu-ray technology is that the laser beamcan be focused much more tightly at the surface of the disc. Tight focus means that a smaller spot will be produced on the surface on the disc, and when the spots become smaller there will naturally be room for more information on each disc. The minimum spot size of any laser depends on a naturally accruing phenomenon called diffraction. The narrow beam of light sent out from a laser will always diverge into a wider beam eventually, due to the natural diffraction of waves. Diffraction will also occur the waves meet an obstruction. By reducing the wavelength of a laser, we can affect the diffraction.

In Blu-ray technology, the diffractions is also affected by the fact that the lens used to focus the light has a higher numerical aperture than the lenses found in ordinary DVDs - 0.85 instead of 0.6. Blu-ray technology based appliances are also equipped with a dual-lens system of supreme quality, and the cover layer has been made thinner in order to prevent unwanted optical effects. All this makes it possible for a Blu-ray laser to focus on much smaller spots. The optical improvements are accompanied with a new method for encoding data which makes it possible to store even more data on the Blu-ray disc.



The standard for Blu-ray technology has been developed as a joint venture between several major manufacturers of PCs and consumer electronics, including Sony and Philips. The group is called the Blu-ray Disc Association (BDA). The first Blu-ray recorder was launched in Japan in 2003, by Sony. Today, Samsung, JVC, Matsushita (Panasonic) and LG Electronics are all examples of companies using Blu-ray technology in their products. Hewlett Packard has announced that they will release desktop PCs equipped with Blu-ray technology in late 2005.

The main competitor for the Blu-ray technology is the HD DVD format which is also capable of storing more information than a normal DVD. The Blu-ray technology does however allow for more information per layer than the HD DVD format – 25 GB compared to 15 GB. The Blu-ray technology will on the other hand most likely be more expensive to support, at least initially, which can make the HD DVD a tempting alternative. In a Blu-ray disc, the data is stored extremely close to the surface. This made the first Blu-ray discs extremely vulnerable to scratching and many users preferred the tougher HD DVD discs. Since 2004, all Blu-ray discs are coated with a clear polymer called "Durabis" which makes them much more durable. According to the developers of Durabis, the TDK Corporation, a coated Blu-ray disc will work even after being attacked with a screwdriver.

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