uCertify Articles » 220-604 http://www.ucertify.com/article Just another WordPress weblog Wed, 04 Nov 2009 00:00:00 +0000 http://wordpress.org/?v=2.8.4 en hourly 1 What is 802.11g? http://www.ucertify.com/article/what-is-80211g.html http://www.ucertify.com/article/what-is-80211g.html#comments Wed, 28 Oct 2009 00:00:00 +0000 uCertify 1401425

The 802.11g standard, defined by IEEE, is an extension to the 802.11b standard of wireless network. It operates in 2.4-GHz band and brings data rates up to 54Mbps using Orthogonal Frequency-Division Multiplexing (OFDM) technology. Since the 802.11g standard is backward compatible with 802.11b, an 802.11b device can interface directly with an 802.11g access point.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-80211g.html/feed 0 What is SO-DIMM? http://www.ucertify.com/article/what-is-so-dimm.html http://www.ucertify.com/article/what-is-so-dimm.html#comments Mon, 26 Oct 2009 00:00:00 +0000 uCertify 1301041

Small Outline Dual Inline Memory Module (SO-DIMM) is a type of memory module that comes in 72 pins and 144 pins. The 72-pin SO-DIMM supports 32-bit transfers, and the 144-pin SO-DIMM supports 64-bit transfers. It was introduced for laptops. SO-DIMMs come in smaller packages, consume lesser power, but are more expensive than DIMMs.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-so-dimm.html/feed 0 What is the FAT32 file system? http://www.ucertify.com/article/what-is-the-fat32-file-system-2.html http://www.ucertify.com/article/what-is-the-fat32-file-system-2.html#comments Thu, 10 Sep 2009 00:00:00 +0000 uCertify 2500056

The FAT32 file system is an enhancement of the FAT file system. It is more advanced and reliable than all the earlier versions of the FAT file system. It manages storage space on large hard disks more efficiently than the FAT16 file system. It uses a smaller cluster size than the FAT16 file system on the hard disk, thereby reducing the amount of space on the hard disk when users save small files. The FAT32 file system supports hard disk drives larger than 2GB and up to 2TB.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-the-fat32-file-system-2.html/feed 0 What is IEEE 802.11b? http://www.ucertify.com/article/what-is-ieee-80211b-2.html http://www.ucertify.com/article/what-is-ieee-80211b-2.html#comments Fri, 28 Aug 2009 00:00:00 +0000 uCertify 1401452

The IEEE 802.11b standard applies to wireless LAN networks that use radio waves as the transmission medium. These networks each have a separate media access control mechanism, known as Carrier Sense Multiple Access with Collision Avoidance (CSMS/CA), that works like the CSMA/CD mechanism used by the Ethernet. The difference is that in this protocol, when a computer sends its signals, the receiving computer performs a cyclical redundancy check and sends an acknowledgement message to the sending computer if no error is detected.

The IEEE 802.11b networks run at the transmission speed of 11 Mbps with a fallback to 5.5, 2, and 1 Mbps in the 2.4 GHz bandwidth. The radio transmission medium used by these networks is called Direct Sequence Spread Spectrum (DSSS).

Share/Bookmark]]> http://www.ucertify.com/article/what-is-ieee-80211b-2.html/feed 0 What is ECP? http://www.ucertify.com/article/what-is-ecp-2.html http://www.ucertify.com/article/what-is-ecp-2.html#comments Sun, 23 Aug 2009 00:00:00 +0000 uCertify 1401139

Enhanced Capabilities Port (ECP) is a high-speed parallel port developed by Hewlett-Packard and Microsoft in 1992. It offers improved performance for the parallel port and requires special hardware logic. ECP ports support high throughput communications.

ECP is an improved version of Enhanced Parallel Port (EPP). Unlike EPP, ECP supports Direct Memory Access (DMA). The ECP ports can be turned into EPP or standard parallel ports using BIOS. However, it is recommended that the port be placed in ECP mode for the best throughput.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-ecp-2.html/feed 0 Storage Devices and Media http://www.ucertify.com/article/storage-devices-and-media-2.html http://www.ucertify.com/article/storage-devices-and-media-2.html#comments Sat, 22 Aug 2009 00:00:00 +0000 uCertify 1301300

A storage medium is an important part of a computer. Storage media contains data that are being accessed by users and is used to save data. It also saves files that a computer needs to operate. Storage devices and media come in different technologies, sizes, capacities, etc.

Following are the types of storage devices and media:

Hard Disk Drive (HDD)

Hard disk drive is used to store users’ data as well as operating system files. Data stored on it can be accessed quickly. Hard disk drive is generally installed inside the computer case. It can store large amount of data. It provides fast read/write performance. HDD can be connected to a computer by the Integrated Device Electronics (IDE), Small Computer System Interface (SCSI), and SATA interface. It consists of inflexible platters coated with material in which data is recorded magnetically with read/write heads.

Integrated Digital Electronics (IDE) is an interface primarily used to connect hard disk and CD Drives in a computer. The IDE-ATA specification provides support for four drives, using two connectors on the motherboard. IDE/ATA interface is best suited for personal computers where only one or two devices would be attached (one hard disk, and one CD Drive). It is reliable and cost effective. In large or medium size organizations where multiple devices are required to support a multi user environment, SCSI is a better alternative.

Small Computer System Interface (SCSI) is a fast interface, primarily used for high performance workstations and servers. The devices attached to it communicate with each other independently, i.e., without CPU intervention. It can also connect external devices. It is commonly used to connect hard disk drives and CD drives. It is more expensive than IDE, but supports a multi-user environment.

Floppy Disk Drive and Floppy

Floppy disk drive is used to read/write data on a floppy disk. It is installed inside the computer case and connected to the computer motherboard using a floppy drive controller.

A floppy disk is a magnetic storage device. It has a thin magnetic film as a storage media, which is protected by a plastic cover. Earlier, floppy disks used to be of 5.25 inches square, but now most computers use floppy disks that are 3.5 inches square. The 5.25 inch floppy disk is obsolete now. It is a removable media. Therefore, users can transfer data from one computer to another using a floppy disk. The limitation with the floppy drive is that it cannot store large amount of data. A 5.25 inch floppy disk can store 1.2 MB of data, whereas a 3.5 inch floppy disk can store up to 2 MB of data.

CD Drive and CDs (Compact Discs)

CD drive is used for read/write operations on CDs. The CD drives that are capable of performing write operations on CDs are also known as CD burners. However, most of CD drives on computers have read only capability. CD drives with read-only capability is also known as CD-ROM (Compact Disc Read-Only Memory) drives. A CD drive is installed inside the computer case and can be connected to IDE, SCSI, SATA, or firewire interface. CD drives come with different data transfer speeds. The first CD drive was introduced with a data transfer rate 150 Kbps. After 150 Kbps speed drive, the 2X speed CD drive with 300 Kbps of data transfer speed was introduced. Currently CD drives with up to 52X data transfer speed are available.

CD-ROM (Compact Disc Read-Only Memory) is a type of removable optical media. It can store up to 1GB of data, although most common CD-ROMs store 700MB of data. It comes in standard size and format, so users can load any type of CD-ROM into any CD drive or CD-ROM player. Once data is written on CD-ROM, it cannot be erased or changed. It is a popular media among hardware and software vendors to distribute software and applications.

CD-R (Compact Disc-Recordable) is a removable optical recordable disc. On this type of disk, data can be written only once, and cannot be deleted.

CD-RW (CD-ReWritable) is a removable optical recordable disc. In CD-RW, written information can be erased and new data can be recorded. CD-RW disk can be written only in a CD-RW recorder, not in a normal CD recorder drive However, a CD-RW recorder can also record standard CD-R disks.

DVD drive and Digital Video Disc (DVDs)

DVD drive is used for read/write operations on DVDs. The drives that are capable of performing write operations on DVDs are also known as DVD burners. There are many DVD burning technologies such as DVD+R, DVD+RW, etc.

DVD-ROM is a removable optical disc storage media. It is used for data storage, including movies with high quality audio and video. DVD-ROMs look same as CDs, their physical dimensions being the same, but they are encoded in a different format and at a much higher density. A DVD-ROM can store up to 4.3GB of data.

Tape Backup device

Tape backup device is used for taking backup of very large amount of data. It can be installed inside or outside a computer. It uses digital or analog magnetic tape medium to store data. It has slow read/write performance and is used for archival purposes. This technology is being obsolete, as optical disc media is used for this purpose.

MMC (MultiMediaCard)

The MultiMediaCard (MMC) is a flash memory memory card standard. MMC has the size of 24 mm x 32 mm x 1.5 mm. MMC originally used a 1-bit serial interface, but new version cards allow transfers up to 8 bits at a time. MMC cards are used in mobiles and digital cameras. Now MMC cards are superseded by Secure Digital (SD) cards. However, MMC cards can be used in any device that supports SD cards. Modern computers, both laptops and desktops, have SD slots that can read MMC cards.

Secure Digital (SD) cards

Pen drive

Pen drive is also known as USB flash drive. It is a small device used to transfer data from one computer to another using USB ports. Pen drives of various capacities, ranging from 32 MB to 1 GB, are available. When a pen drive is plugged into the USB port, Windows Explorer shows it as a removable drive. This interface allows users to copy data easily on the pen drive.

HD DVD

High Density DVD (HD DVD) is an optical disc format designed for the storage of large amount of data and high-definition video. This standard was jointly developed by a group of consumer electronics and PC companies, led by Toshiba. The HD DVD disc is an enhanced version of the DVD format so that it can accommodate high-definition video. It uses blue-violet laser that enables it to store more information in the same amount of physical space. It has a single-layer capacity of 15 GB and a dual-layer capacity of 30 GB. HD DVD discs can be played on standard DVD players.

Share/Bookmark]]> http://www.ucertify.com/article/storage-devices-and-media-2.html/feed 0 What is SD card? http://www.ucertify.com/article/what-is-sd-card-2.html http://www.ucertify.com/article/what-is-sd-card-2.html#comments Fri, 21 Aug 2009 00:00:00 +0000 uCertify 1301286

Secure Digital (SD) card is a non-volatile memory card format used in portable devices such as mobile phones, digital cameras, and handheld computers. SD cards are based on the older MultiMediaCard (MMC) format, but they are a little thicker than MMC cards. Generally an SD card offers a write-protect switch on its side. SD cards generally measure 32 mm x 24 mm x 2.1 mm, but they can be as thin as 1.4 mm. The devices that have SD card slots can use the thinner MMC cards, but the standard SD cards will not fit into the thinner MMC slots. Some SD cards are also available with a USB connector. SD card readers allow SD cards to be accessed via many connectivity ports such as USB, FireWire, and the common parallel port.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-sd-card-2.html/feed 0 What is PCI Express (PCIe)? http://www.ucertify.com/article/what-is-pci-express-pcie-2.html http://www.ucertify.com/article/what-is-pci-express-pcie-2.html#comments Fri, 21 Aug 2009 00:00:00 +0000 uCertify 1301288

PCI Express (PCIe), also known as 3rd Generation I/O (3GIO), is a type of computer bus. It is a new I/O bus technology that has more bandwidth than PCI and AGP slots. It uses two low-voltage differential pairs, at 2.5Gb/s in each direction. It is designed to replace PCI and AGP expansion slots. The bus is available in several different bus widths: x1, x2, x4, x8, x12, x16, and x32. PCIe is able to transfer data in both directions at a time. PCIe hardware will work on operating systems that support PCI.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-pci-express-pcie-2.html/feed 0 What is Trojan horse? http://www.ucertify.com/article/what-is-trojan-horse-2.html http://www.ucertify.com/article/what-is-trojan-horse-2.html#comments Wed, 19 Aug 2009 00:00:00 +0000 uCertify 1301109

Trojan horse is a malicious software program code that masquerades itself as a normal program. When a Trojan horse program is run, its hidden code runs to destroy or scramble data on the hard disk. An example of a Trojan horse is a program that masquerades as a computer logon to retrieve user names and password information. The developer of a Trojan horse can use this information later to gain unauthorized access to computers. Trojan horses are normally spread by e-mail attachments. Unlike viruses, Trojan horses do not replicate themselves but only destroy information on hard disks.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-trojan-horse-2.html/feed 0 What is the FAT32 file system? http://www.ucertify.com/article/what-is-the-fat32-file-system.html http://www.ucertify.com/article/what-is-the-fat32-file-system.html#comments Fri, 17 Jul 2009 00:00:00 +0000 uCertify 2500056

The FAT32 file system is an enhancement of the FAT file system. It is more advanced and reliable than all the earlier versions of the FAT file system. It manages storage space on large hard disks more efficiently than the FAT16 file system. It uses a smaller cluster size than the FAT16 file system on the hard disk, thereby reducing the amount of space on the hard disk when users save small files. The FAT32 file system supports hard disk drives larger than 2GB and up to 2TB.

Share/Bookmark]]> http://www.ucertify.com/article/what-is-the-fat32-file-system.html/feed 0