Category: Computers

IBM came back to the fore when color started to appear in computer displays. The CGA standard, introduced in 1981 and primative by today’s standards, was still color; even if only 16 of them. Because the first PCs were for business, the color did not first catch on and the MDA monochrome standard we more often used. As prices came down and clones of the IBM PC were introduced, CGA became more of a standard.

The CGA card came with 16 KB of video memory and supported several different modes:

Text mode which included 80×25 text (like the MDA system) in 16 colors. The resolution, however was lower as each character was made up of 8×8 pixels instead of the MDA’s 9×14 pixels. A 40×25 text mode was also supported in 16 colors. In both, the foreground and background colors could be changed for each character.

Monochrome graphics mode which displayed graphics at 640×200 pixels. This was lower than the Hercules card but seemed to serve the purpose for an initial release and this was quickly replaced with the EGA standard.

Color graphics mode which came in two flavors: a 320×200 pixel mode with four colors and a lesser-used resolution of 160×200 in 16 colors. The four-color mode only had two official palettes to choose from:

Magenta, cyan, white and background color (black by default).
Red, green, brown/yellow and background color (black by default).
The 16-color graphic mode used a composite color mode instead of the 16 colors of the CGA text above. Because the color technique was not supported in the BIOS there was little adoption of that mode except by some games.

The CGA color palette was based on the Motorola MC6845 display controller. Red, green, and blue were created by the three cathode rays with black being an absence of cathode rays. The other colors were mixes of two different colors and white used all three color beams. An “intensifier” bit gave a brighter version of the basic 8 colors for a total of 16. There was one exception to this. In the normal RGB model color #6 should be a dark yellow (#AAAA00) however IBM changed the monitor circuitry to detect it and lower its green component to more closely match a brown (#AA5500) color. Other monitor makers mimiced this which is why the intense version of #6, brown, turned out to be a bright yellow as the intense version was not so modified. There is no clear reason expressed why IBM did this but it’s speculated they wanted to match 3270 mainframe colors. So, the colors appeared as…

Color 0 – Black – #000000 and the intense version, color 8 – Dark Grey – #555555
Color 1 – Blue – #0000AA and the intense version, color 9 – Bright Blue – #5555FF
Color 2 – Green – #00AA00 and the intense version, color 10 – Bright Green – #55FF55
Color 3 – Cyan – #00AAAA and the intense version, color 11 – Bright Cyan – #55FFFF
Color 4 – Red – #AA0000 and the intense version, color 12 – Bright Red – #FF5555
Color 5 – Magenta – #AA00AA and the intense version, color 13 – Bright Magenta – #FF55FF
Color 6 – Brown – #AA5500 and the intense version, color 14 – Bright Yellow – #FFFF55
Color 6 in some clone monitors -Yellow – #AAAA00
Color 7 – Light Grey – #AAAAAA and the intense version, color 15 – Bright White – #FFFFFF (which you won’t see because the background here is white)
There were several tweaks to the CGA text and graphics systems which resulted in different default background colors, different colored borders, and other tweaks which gave the appearance of the CGA system having more than the graphic modes above; but, these were all tweaks and not changes to the basic system itself.

Refresh rate for CGA monitors was increased to 60 Hz as a result of eyestrain complaints from the MDA 50 Hz rate. (The higher the refresh rate the less likely pixels on the screen will flicker as the phosphor is refreshed at a faster rate.)

See here for more details and pictures.

But, the low resolution of CGA begged for higher resolutions. To fill those demands IBM developed EGA…

Just like the heart the motherboard supplies life to a computer, if it fails the computer will no longer function. The System board, main board or motherboard is the most important circuit board inside a computer besides being the largest it also contains the Central Processing Unit or CPU. All the devices inside a computer communicate with the motherboard. The motherboard is the PC’s center of activity. It hosts the largest single collection of chips of any PC component and serves as the “street system” for the grid of wires that link all the components, making it possible for them to communicate. The motherboard defines the computer’s limits of speed, memory, and expandability. A computer needs more than just a CPU and memory. To function properly it needs devices, such as a keyboard and a mouse. It also needs output devices, like monitors and sound cards, to cope with the powerful graphics and sound capabilities of the programs available today.

A computer also needs “permanent” storage devices, such as floppy disk drives and hard disk drives, to store data when it is turned off. It is the function of the motherboard to provide the connectivity for all these devices, as well as for the CPU, RAM, and support ICs. There are nine major components in a mother board.

1. The Central Processing Unit.

2. The chipsets Northbridge and Southbridge that support the CPU.

3. RAM random access memory to hold data and instructions.

4. Cache memory to speed up the memory accessed.

5. Communication on the system board via the BUS.

6. Slots to connect devices such as a video card, or modem.

7. BIOS which holds configuration to allow a computer to boot properly.

8. CMOS battery which acts as a backup when your computer is shutdown.

9. A power supply which enables the computer to boot and supplies power to all the devices directly connected to the motherboard.

尽管任天堂的Wii目前依旧是最热卖的游戏主机，索尼的PS3只能苦苦追赶，但独立调研机构Strategy Analytics近日发布的报告表明，PS3才将是这代游戏机的最终霸主。

Strategy Analytics认为，任天堂的Wii的最鼎盛时期已经过去，其销量将从2011年开始下滑；而索尼的PS3和微软的Xbox 360却还在增长，并预计索尼PS3将在2013年成为全球最大的游戏平台。当这代游戏机寿终正寝时，索尼PS3的累计销量预计将达到1.27亿部，而任天堂Wii则为1.03亿部。

分析师David Mercer表示，任天堂Wii吸引了不少新玩家，但是他们的销量开始呈现下滑趋势，特别是在成熟市场。Wii的销量将在2011年开始下滑，而索尼PS3和微软Xbox 360到2012-2014年时才会达到其销售峰值。

此外，Strategy Analytics认为加入索尼动作感应器的加入以及向3D功能的升级都会帮助PS3销量的增加。

对于今年的游戏机市场，Strategy Analytics预计整体销量将会同比下降9%。任天堂Wii还将以1750万销量继续领跑，索尼PS3将以1400万排名第二，微软Xbox 360将卖出1050万，索尼PS2也会有550万的销量。

Roughly, a USB flash drive is a device to store data in a flash memory with a USB interface integrated on it. This way the memory will be rewritable and also removable as a disk, but it is much smaller, will weigh much less and it is more comfortable to carry.

The storage capacity if a USB flash drive can vary a lot. They range from some mb to up to 256gb and every day passing they are larger and cheaper. The best USB flash drives allow to up to 1 million of cycles ( the times you can erase and write them) and may store the data with no errors for years.

The main function of these USB flash drives is the same intended for floppy disks in the past, but the advantage is that they are much smaller, the capacity is much higher and they are safer and more resistant. A typical USB flash drive won’t break if it falls to ground and will not get scratches as a common CD or DVD. At it is very little it can be stored in a pocket.

USB flash drives have a limited write / delete life so it is not recommendable to waste their life with unnecessary procedures like defragmentation. USB flash drives may be defragmented but it is barely useless because there are no mechanical parts in the drive and thus no mechanical head will move from a fragment to another. It may offer a little advantage because will need to access to less sectors but doing so will shorten the life of the flash drive in a great amount.

A USB flash drive can be partitioned as a Hard Drive but again it has little utility because installing a system in a USB flash drive will make too much writes and deletes and the life of the drive will be shortened.

The main disadvantages of an USB flash drive are for example the limited number of cycles before the device will fail. This may be considered if you plan to use a USB flash drive to run software or to use it as an OS. Another great disadvantage is that most USB flash drives do not include a write protection switch and thus, they are sensitive to be infected with a virus very easily. Their size is very convenient but on the other hand it is very easy to misplace them or leaving them behind.

About the price, they are very expensive if we compare to HD’s in the per unit storage cost, but when it comes to small capacities like for example a 8gb drive, they are much cheaper than a 8gb HD. They are very convenient for small capacities and to be used to carry personal data at all times like pictures, music, videos, resumes, documents and even medical information in the case of an accident because of their high resistance to water, impact and other inconveniences although they are not designed for this purpose.

A Computer CPU is, in simple terms, the “brain” of your computer. It is also known as the processor. CPU’s are used to process everything from basic to complex functions. Every time something needs to be computed it gets sent to the CPU. It attaches directly to the motherboard using a socket and is usually cooled by a heat sink or fan. Depending on the manufacturer of the computer processor, the socket types will be different.

Make sure that your CPU has the correct socket type for your motherboard. Not all CPU’s have pins on the bottom side, but be careful with ones that do. The pins can be easily bent while attaching the CPU to the motherboard. Processors have drastically advanced over the years from the Pentium 4 Processor, to the Core 2 Duo, and now to the Quad Core Processor.

There are several different manufacturers of CPU’s such as Intel and Athlon. Each manufacturer has many versions of their processors, differing in specifications. To identify one CPU from another, each version is given a core name. Taking Intel for example, a couple of the different cores might be: Core 2 Duo or Core 2 Quad. Each CPU has a clock speed, which refers to the speed that the CPU runs. This is the most important indicator of a CPU’s performance level. Another very important performance factor of a CPU is the FSB. The FSB is the data transfer speed between the CPU and the RAM. A CPU also has an L2 Cache speed. Level-2 cache is an area of fast memory inside the CPU. This memory is used to store more frequently used data so it will not have to be received from slower RAM. The larger the L2 Cache, the faster your processor will be. The technological advancement of processors has made them more efficient in many ways.