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Floppy Disk Drives / Floppy Disks

Floppy disk drives were originally introduced commercially as a read-only device in the early 1970s. These early floppy disk drives were used to hold microcode and diagnostics for large IBM mainframe computer systems. These disk drives were using 8-inch floppy diskettes recorded on only one side. By changing these diskettes inside the floppy drive, technicians could easily update the microcode to the latest revisions or load diagnostics easily. The storage capacity of these early readonly drives was less than 100 kilobytes.
In 1973 a new upgraded 8 inch drive with read/write capability and a capacity of about 250 kilobytes began shipping which IBM used in data entry systems. This drive incorporated many technical improvements and became a model for drives still in use today. As time went on, designers learned how to reliably record on both sides of the diskette as well as increase the density of the data recorded on the diskette.
Modern floppy drives and diskettes (3.5 inch) have evolved to a much smaller size with larger capacities as well. In 1980, the 3.5 inch floppy drive and diskette was introduced by Sony. During the early 1980's many competing formats were tried to compete with the 3.5 inch drives. Over time the industry settled on the 3.5 inch format which was standardized and manufactured by many companies. Today's standard 3.5 inch diskettes hold a formatted capacity of 1.44 megabytes while still using the same basic technology of the second generation 8 inch drives.
Hard-Disk Drives (Hard Disks)

The hard drive, also called the hard disk or fixed disk, is the primary storage unit of the computer. It is always labeled the C drive. Additional drives are labeled after it as the D, E, F, etc. It has several read/write heads that read and record data magnetically on platters, a stack of rotating disks inside the hard drive.

Types of Hard Drives
(1) Bournolli has a mechanism that acts as a fly wheel. When the HD spins the disk follows gravities course and is lifted up a few centimeters causing the Read/Write heads to touch. When it stops spinning, the HD will fall back down the few centimeters.
(2) Magnetic Optical Drive has the best storage capacity. It has the same principles as the Bournolli, but is mixed with the Compact Disc technology so that the Read/Write head puts data in order and the laser reads off of it.
(3) Standard Magnetic Drive The standard magnetic drive is less complex and less expensive than the others. It stores data with a read/write head which sends a pulse of electricity through causing the magnetic films electrons to line up in a certain way.
Types of Hard Drive Connections
(1) Integrated Device Electronics (IDE)
(2) Small Computer Interface (SCSI)
(3) Enhanced Integrated Drive Electronics (EIDE)

The CD-ROM Technology.

The Compact Disc-CD was invented in 1982 by two well-known companies, Philips and Sony. This was an Audio CD, digital audio. Soon the computer industry recognized that the large amount of digital audio data could be replaced by digital computer data.
CD-ROM (Compact Disc Read-Only Memory) represents a new important tool for the storage, retrieval, and the distribution of information. CD-ROMs can store and play back audio, video, graphic images, digital data, and digitized text.

Types of Compact Disks.
(1) CD-DA : Audio CD, Digital Audio by Philips and Sony
(2) Photo CD : Developed by Kodak and Philips
(3) Video CD : Can hold around 70 minute of video footage
(4) CD Extra : For Multimedia and developed in 1996
(5) CD-R : Well known technology for WORM disks
(6) CD-RW : Rewritable (erasable)-CD, developed in 1995

Digital Video Disc (DVD)

Digital Video Disc or Digital Versatile Disc (DVD), an optical storage device that looks the same as a compact disc but is able to hold about 15 times as much information and transfer it to the computer about 20 times as fast as a CD-ROM. A DVD, also called a Super Density disc (SD), can hold 8.5 gigabytes of data or four hours of movies on a side; double -sided and rewriteable DVD discs are available now.

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