.ISO Disk Images: A Background and Address to Common Problems Sunday, August 16, 2009 4:02 PM
So the digital age is here. You can make popcorn from your cell phone while browsing the internet, buy furniture from Sweden while playing poker with a man in Denmark, and create and edit models of nuclear weapon systems and print them out to color in; however you still have shelves of CD's physically storing your digital data. This is often seen as one of the most fundamentally outdated technology systems for mass personal data storage. While CD's are good for permanent records and important files, the physical space they take up often outweighs their usefulness in data storage. After all, a single CD-R, CD-RW, or CDR+ only stores 700 MB at maximum capacity. That's about a fifth of what you store on a single $10 4GB flash drive. So what? CD's are beginning to look like floppy diskettes as the technological paradigm shift mercilessly plows forward. Unnecessary, bulky, and inefficient in storing large amounts of data.
This guide however, is not meant to address the rising inadequacy of compact disks, but rather their inability to be versatile. If you want to get a CD to people, the most logical thing to do would be to send it through the mail. This however, is a lengthy, tedious process that can be easily circumvented with a few applications. Programs exist that allow you to copy the disk itself into a digital format. Before you begin, please understand the fundamentals of Compact Disk Storage. As you may know, computers use "Machine Code", which is commonly known as Binary. Binary, being strings of virtual 1's and 0's is just the concept of a charge, or the absence of a charge. Compact Disks do not use electricity, therefore eliminating the use of a "charge" to represent binary signatures. Instead a CD uses a series of pits as illustrated below to store data. Think of a CD as a small mirror. When struck by a laser at 180 degrees perpendicular, a mirror will reflect the light back to it's original source. The pits, which are created when a laser "burns" to a disk, reflect the light away from the source and are collected by sensors. When applied in succession, the result is a series of laser bursts when the disk is spinning.
To make a copy of a CD, theoretically all you need is an exact copy of the pits and the space between them.
Diagram of pits on a CD *Above*
The file format .ISO is just that: a digital copy of the disk. Unlike a copy of the data, an ISO image can not be "read"; meaning you can't access the data within it without burning it to a disk first or mounting it as a file system.
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