TYPES OF DATA STORAGE MEDIA

      The computer has the hardware to storage media. External memory is a hardware device to perform a write operation, the reading and storing data, outside of the major components mentioned above. Examples of external memory is a floppy disk, hard disk, cd-rom, dvd.
Almost all of the external memory is widely used in recent-shaped disk / disk so that data operations performed by the disk rotation. Of this rotation, the rotation of the disc is known unit called the RPM (Rotation Per Minute). The faster the rotation, even the faster access time, Namu is also greater pressure on the plate so that the greater the heat produced. For large-capacity media known some systems that measure its RPM as follows:
• Pre-IDE 3600 RPM
• 5200 RPM IDE
• 5400 RPM IDE / SCSI
• 7200 RPM IDE / SCSI
• SCSI 10 000 RPM
Each has an external memory read and write devices called heads (on disk) and side (on floppy). Each disc has two sides of the head / side, the side 0 and side 1. Each head / side circle is divided into concentric circles called tracks. The same set of tracks from all that is called a cylinder head. A track is further divided into smaller areas called sectors.
A. Floppy disk
Floppy disk drives use a standard consists of two sizes of 5.25 "and 3.5", each of which has a capacity of type 2 Double Density (DD) and High Density (HD).
Floppy disk 5.25 "capacity is 360 Kbytes (for DD) and 1.2 Mbytes (for HD). While the floppy disk 3.5 "capacity is 720 Kbytes (for DD) and ntuk HD). Capacity that can be accommodated by the floppy disk is likely to be small, especially when compared to the needs of data transfer and storage of increasingly large. Floppy disks can only store a text file, because of limited capacity. However, the writing on the floppy disk can be done over and over again, although it took a relatively long time.
2. ZIP drive
ZIP drive from lomega. ZIP small 1.47-inch drive. ZIP drive is to improve the limited capacity owned by the floppy disk. This device consists of a floppy drive and floppy special cartridge, which holds up to 100MB of data mapu. With this much capacity, it can allow people to store graphics and multimedia files.
3. Hardisk
As floppy disks, hard drives also save the data in the form of tracks, sectors, and clusters. Computer operating system based on the sector recorded its cluster. Windows operating system provides a unique number to each cluster and the record address file on your hard drive using the virtual file allocation table (VFAT, Virtual File Allocation Table). VFAT is one method to store and find out the address used cluster file suit. Therefore, VFAT contain any value on each cluster that describes the location of the disk where the cluster is located. Sometimes the operating system considers a cluster as a cluster that is being used, although at the time that the cluster does not contain any files. This is called a lost cluster, and users can free up the cluster (which means it can add disk space) using ScanDisk utility in Windows.
C.1. Nonremovable hard drives (HDD Internal)
Nonremovable internal hard drive is the hard drive remain in the unit and the computer system used to store almost any program, and most of the data file. This type of hard drive consists of several metal plates or glass (glass) 1 to 5.25 inches in diameter (typically 3.5 inches), arranged in a coil shape and contains data on both sides of dishes. Read / write head is located on each side of the disc, is governed by the driving arm that moves back and forth to find the exact location on the disc. All components are protected against anti-air in the packaging so that it can be free from impurities such dust.
Nonremovable hard drive capacity varies between 40 to 300 gigabytes. There's even a hard drive that has reached the terabyte unit is equivalent to thousands of gigabytes. One gigabyte is roughly equivalent to writing all the 20,000 pages, while video and voice files usually measuring 10 megabytes or more.
Round hard disk is much faster than floppy disks, so that the data / programs on the hard disk can be accessed more quickly. Hard drive speed is expressed in units of revolutions per second (rpm) which ranged from 5400 to 7200 rpm. Disk rotation speed is only 360 rpm, while the hard drive at 7200 rpm (roughly equivalent to a speed of 300 miles per hour).
C.2. Portable Hard Drive (HDD External and Removable)
There are two types of portable hard drives, among others:
External hard drives, external hard disk is a disk that can be placed outside the system unit and keep berpembungkus anti air. Via cable, hard drive connected to the computer system unit to a FireWire port, USB or other port. Minimum capacity of 250 gigabytes.
Removable hard drives, removable hard drives or hard-drive cartridge consists of one or two discs fitted head read / writes, protected in rigid packaging and cartridges can be inserted into the drive on a microcomputer system unit. Cartridge, with a capacity of 80 gigabytes or more, usually used to backup and move data files are large, such as a spreadsheet file or desktop-publishing the berukura
4. CD-ROM.
CD-ROM that is now commonly made of resin (polycarbonate) and coated with highly reflective surfaces such as aluminum. Information recorded digitally as microscopic pits on a reflective surface. This process is done using high intensity laser. Perforated surface is then coated by a layer of nodes. Information is read using low-intensity laser that illuminates the translucent layer while the motor rotates the disk. Then the laser intensity is changed after the holes are then reflected in and detected by fotosensor which are then converted into digital data. Writing data on CD-ROM can only be done once. However, the optical disk has advantages in terms of mobility. Its small and thin makes it easier to carry anywhere.
5. DVD (Digital VersatileDisc) Beginning in 1983 the system in the optical disc data storage was introduced with the launch of the Compact Disc Digital Audio. From that time on the optical disc storage technology develops. CD-ROM (Compact Disc Read Only Memory) is a medium for storing data or other information in a very large number (over 600 megabytes). Much greater if we compare it to a floppy disk (1.4 MB)
DVD is the next generation of storage technology using optical media disc. DVD has a capacity of the people are much larger than regular CD-ROM, which reached 9 Gbytes. DVD technology is now being used widely by major music companies and film, making it the most popular electronic products in the past 3 years since it was first introduced.
DVD-ROM technology developments even faster than CD-ROM. 1x DVD-ROM allows the average data transfer 1321 MB / s with an average burst transfer 12 MB / s. The bigger the cache (memory buffer) owned DVD-ROM, the faster delivery of data that can be done.
DVD provides a format that can be written only once or more, which is called the Recordable DVD, and have a variety of versions, namely: DVD-R for General, once the writing of DVD-R for Authoring, only once DVD-RAM writing, can be written DVD-RW over and over again, be written repeatedly DVD + R, only once the writing of each version of DVD recorders can read DVD-ROM disc.