Word of the Day: CMOS

#WOTD (1)

Stands for “Complementary Metal Oxide Semiconductor.” This technology is typically used in making transistors. The “complementary” part of the term unfortunately does not mean these semiconductors are free. Instead, it refers to how they produce either a positive or negative charge. Because CMOS-based transistors only use one charge at a time, they run efficiently, using up very little power. This is because the charges can stay in one state for a long period of time, allowing the transistor to use little or no power except when needed. Because of their wonderful efficiency, processors that use CMOS-based transistors can run at extremely high speeds without getting too hot and going up in flames. You may also find CMOS memory in your computer, which holds the date and time and other basic system settings. The low power consumption of CMOS allows the memory to be powered by a simple Lithium battery for many years.

– definition from TechTerms

Word of the Day: Terahertz

Terahertz is a unit of measurement sometimes used to measure computer clock speeds. One terahertz is equal to 1,000 gigahertz (GHz), or 1,000,000,000,000 hertz (Hz). Since the majority of personal computers operate between two and four gigahertz, most computer clock speeds are not measured in terahertz. Instead, terahertz is more often used to measure the total speed of computing clusters or supercomputers.

Like gigahertz, terahertz only measures frequency, or cycles per second. Since some processors require more cycles to process instructions than others, terahertz is not always an accurate measurement of overall computing power. Additional factors, such as RAM speed, bus speed, and processor cache, also effect a computer’s performance. Therefore, other units of measurements, such as MIPS and FLOPS are typically used to measure the computing performance of supercomputers and other high-end computer systems.

Abbreviation: THz.

– definition from TechTerms

Word of the Day: LIFO

Stands for “Last In, First Out.” LIFO is a method of processing data in which the last items entered are the first to be removed. This is the opposite of LIFO is FIFO (First In, First Out), in which items are removed in the order they have been entered.

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To better understand LIFO, imagine stacking a deck of cards by placing one card on top of the other, starting from the bottom. Once the deck has been fully stacked, you begin to remove the cards, starting from the top. This process is an example of the LIFO method, because the last cards to be placed on the deck are the first ones to be removed.

The LIFO method is sometimes used by computers when extracting data from an array or data buffer. When a program needs to access the most recent information entered, it will use the LIFO method. When information needs to be retrieved in the order it was entered, the FIFO method is used.

– definition from TechTerms

Word of the Day: Pixel

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The term “pixel” is actually short for “Picture Element.” These small little dots are what make up the images on computer displays, whether they are flat-screen (LCD) or tube (CRT) monitors. The screen is divided up into a matrix of thousands or even millions of pixels. Typically, you cannot see the individual pixels, because they are so small. This is a good thing, because most people prefer to look at smooth, clear images rather than blocky, “pixelated” ones. However, if you set your monitor to a low resolution, such as 640×480 and look closely at your screen, you will may be able to see the individual pixels. As you may have guessed, a resolution of 640×480 is comprised of a matrix of 640 by 480 pixels, or 307,200 in all. That’s a lot of little dots.

Each pixel can only be one color at a time. However, since they are so small, pixels often blend together to form various shades and blends of colors. The number of colors each pixel can be is determined by the number of bits used to represent it. For example, 8-bit color allows for 2 to the 8th, or 256 colors to be displayed. At this color depth, you may be able to see “graininess,” or spotted colors when one color blends to another. However, at 16, 24, and 32-bit color depths, the color blending is smooth and, unless you have some kind of extra-sensory vision capability, you should not see any graininess.

– definition from TechTerms

Word of the Day: Checksum

A checksum is a value used to verify the integrity of a file or a data transfer. In other words, it is a sum that checks the validity of data. Checksums are typically used to compare two sets of data to make sure they are the same. Some common applications include verifying a disk image or checking the integrity of a downloaded file. If the checksums don’t match those of the original files, the data may have been altered or corrupted.

#WOTD (1)

A checksum can be computed in many different ways, using different algorithms. For example, a basic checksum may simply be the number of bytes in a file. However, this type of checksum is not very reliable since two or more bytes could be switched around, causing the data to be different, though the checksum would be the same. Therefore, more advanced checksum algorithms are typically used to verify data. These include cyclic redundancy check (CRC) algorithms and cryptographic hash functions.

It is rare that you will need to use a checksum to verify data, since many programs perform this type of data verification automatically. However, some file archives or disk images may include a checksum that you can use to check the data’s integrity. While it is not always necessary to verify data, it can be a useful means for checking large amounts of data at once. For example, after burning a disc, it is much easier to verify that the checksums of the original data and the disc match, rather than checking every folder and file on the disc.

Both Mac and Windows include free programs that can be used to generate and verify checksums. Mac users can use the built-in Apple Disk Utility and Windows users can use the File Checksum Integrity Verifier (FCIV).

– definition from TechTerms

Word of the Day: Firewire

FireWire is an I/O interface developed by Apple Computer. It is also known as IEEE 1394, which is the technical name standardized by the IEEE. Other names for IEEE 1394 include Sony i.Link and Yamaha mLAN, but Apple’s FireWire name the most commonly used.

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There are two primary versions of the FireWire interface – FireWire 400 (IEEE 1394a) and FireWire 800 (IEEE 1394b). FireWire 400 uses a 6-pin connector and supports data transfer rates of up to 400 Mbps. FireWire 800 uses a 9-pin connector and can transfer data at up to 800 Mbps. The FireWire 800 interface, which was introduced on Macintosh computers in 2003, is backwards compatible with FireWire 400 devices using an adapter. Both interfaces support daisy chaining and can provide up to 30 volts of power to connected devices.

FireWire is considered a high-speed interface, and therefore can be used for connecting peripheral devices that require fast data transfer speeds. Examples include external hard drives, video cameras, and audio interfaces. On Macintosh computers, FireWire can be used to boot a computer in target disk mode, which allows the hard drive to show up as an external drive on another computer. Mac OS X also supports networking two computers via a FireWire cable.

While FireWire has never been as popular as USB, it has remained a popular choice for audio and video professionals. Since FireWire supports speeds up to 800 Mbps, it is faster than USB 2.0, which maxes out at 480 Mbps. In fact, even FireWire 400 provides faster sustained read and write speeds than USB 2.0, which is important for recording audio and video in real-time. Future versions of IEEE 1394, such as FireWire 1600 and 3200, were designed to support even faster data transfer speeds. However, the FireWire interface has been superseded by Thunderbolt, which can transfer data at up to 10,000 Mbps (10 Gbps) and is backwards compatible with multiple interfaces.

– definition from TechTerms

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