What are those objects on your desktop?

Icons can be thought of merely as regions of your screen. When the system detects a "mouseover" or "mouseclick" activity in one of those regions, it performs some action, like opening a file or running a program associated with the object you're hovering over or clicking on.

Icons can be thought of as "surrogates" for resources on your machine, much like a library's catalogue cards are "surrogates" for books, movies, etc. in the collection. Some icons point you to programs, others to file folders, others to pictures, etc. But just where are such resources kept?

There are really only a couple of places they could be kept in a computer's memory: a) either in Random Access Memory (RAM) or b) somewhere on a disk of some sort – an internal "hard" disk, perhaps, or a removable "floppy" disk, a CD-ROM or a DVD.

When you run a program, say a word processor, you want a copy of that program's machine language code (its compiled version) put into RAM where it will run faster. But RAM is not a good place to keep things permanently – it is too "volatile". That is, if the computer is shut down, you lose what is in RAM.

Therefore. most of those icons probably point to things kept on disks. Data on disks is kept in files. Particular types of files (.jpg or .gif pictures, or .doc documents, for instance), can be "associated" with programs used to create or to view them.

When you click on an icon with a "W" symbol, for instance, and the name of a document below it, you are telling the machine to open the document with the program used to create it, namely, Microsoft Word.

File folders are icons pointing to "directories" containing names of files grouped together for human convenience. The computer really doesn't care where on its disks the files are actually stored. What matters is that the list of names or icons makes them appear to be in one place. Along with each file name is a numeric address, telling the machine where to look on the disk for that file.

When you move an icon from the folder "My Documents" into the "Recycle Bin", you are really just moving its name and address from one directory to another. When you empty the recycle bin, you are removing the unwanted file names from all directories. Thus, nobody can find those files again under normal circumstances.

However, the data contained in those files won't actually be removed from the disk when you "logically delete" the file by zapping its name. The data will only be "physically" deleted when you run a program to clean up the disks.

When you run a program, say a word processor, it gets loaded into RAM, and some RAM is also set aside for you to use as work space for the document you are creating. To keep your work, you must "save" the file to a disk. Clever programs (for example, MS Word), keep updating temporary copies of your work somewhere on the disk while you are writing them, in case the power fails or the program "crashes" due to an error condition. When the program comes up again, it consults its temp files, and hopefully, allows you to recover all but, say, the last 2 minutes of work you did.

Copyright © Christopher Brown-Syed 1995-2001. Disclaimers.