1. 1. Optical Disc history—how we got to today from where we started
2. 2. History of ReWritables
1. Optical Disc history—how we got to today from where we started?
On October 1, 1982 Sony introduced the CDP-101, the first Compact Disc audio CD player on the market at a retail price of about $900.
The first Philips CD player was to be named ¡¥Pinkeltje¡¦, after a well-known friendly gnome from a Dutch children¡¦s story. Small and compact, that was the development aim. It had to be a product that was appealing to the eye, easy to operate and smaller than a record player. This was achieved in record time.
The first thing that the developers had to worry about was not the size of the electronics. The circuits could always be further reduced in size later when the product was ready to go into production. What they had to do now was to show that it worked. One crucial factor here was the way in which the sound information was coded. Now that the analog recording of music could no longer be used, a new digital technique had to be developed. The Philips researchers were able to draw on the experience gained with digital signal technology in the field of telecommunications.
In the first prototypes Philips had tested a simple and efficient technique for converting the analog sound signal into digital ones and zeros. With delta modulation, the changes in voltage in the microphone are followed by ones and zeros. A one represents a rise in voltage, a zero represents a fall. In this way, relatively few ones and zeros are required to record the signal accurately. The ones and zeros can be used later to reconstruct the voltage pattern precisely. The disadvantage is that no codes must be lost or else the player quickly loses track of what it is doing. And that is precisely what happened. A duet that had been recorded on a CD in this way was not worth listening to. That was clearly not the way to do it then.
Although the player was a long way from being finished, it seemed important at this early stage in the product development to win the support of both the public and the industry for this idea. Other companies too were already working on audio versions of video discs. AEG-Telefunken was working on a Mini Disc and JVC on an Audio High-Density (AHD) system. In order to prevent a battle between the different, non-compatible systems, Philips had to show quite clearly how far they had progressed. In March 1979 a press conference was organized to let people hear how beautiful digital music could be. The demonstration room was filled with Schubert¡¦s Unfinished Symphony. The prototype had been finished, but the product was not yet ready.
2. History of ReWritables
It¡¦s often said that the only constant in the computer and consumer electronics industries is change. Nonetheless, CD-R and CD-RW has remained a constant and trusted companion for many. CD-R and CD-RW technologies have, of course, evolved over the years but change here has come in practical and tangible improvements to quality, performance and ease of use. Unique compatibility and affordability, at the same time, have made CD-R and CD-RW the popular storage choice of industry and consumers alike.
Some of the earliest (i.e. early 1980's) home computers came with a Floppy Disk and nothing else. For this reason it was called the ""A" drive and, if you were lucky enough to have two of these drives in a machine (for copying disks, for example), then the second one would be called the "B" drive. Later, hard disk drives were introduced. These do not have replaceable diskettes and they are capable of holding much more information. To protect them, they are stored inside the computer case, and they became the "C" drives.
When CDROM drives were introduced, they became the "D" drives. Now there are many more types of storage media available - read-writeable CD-ROMs, Zip drives, and tapes back up drives, just to name a few. Each of these can be assigned as the "E" or with some subsequent drive letter. When computers are linked together, or "networked", many of the programs and files can be stored centrally on a more powerful computer called a "server". This allows us to go to any computer on the system and find the files we have stored, regardless of whether of not we originally created them while we were using a different computer on the network. Most computers in labs, in classrooms and in our libraries are of this type.
CD-Recordable (CD-R) and CD-ReWritable (CD-RW) are members of the Compact Disc (CD) family but unlike the prerecorded pressed audio CDs and CD-ROMs we use every day, CD-R and CD-RW discs can be written by the user. These special discs can hold up to 650 MB of data or 74 minutes of CD or VHS quality audio or video. CD-R discs have a special dye-recording layer that is optically recorded by a laser in the CD-R/RW drive. Information is irreversibly written by creating a pattern of dull marks and shiny spaces, which can be added incrementally, until the disc is full.
CD-RW discs are a little different. They contain a special phase-change metal recording layer that is also optically recorded by a CD-R/RW drive and can be rewritten many times over. As with CD-R, data is written to a CD-RW disc by creating a pattern of dull marks and shiny spaces but, because of the nature of the phase change recording material, data can be recorded over and over (up to 1,000 times.) Once recorded, CD-R discs can be read on any CD audio player, CD-ROM or MultiRead DVD-ROM drive. CD-RW discs don't reflect as much light as do CD-R discs, so they are only readable in newer "MultiRead" CD-ROM and DVD-ROM drives which include the necessary electronics to compensate for the diminished light level.
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