When you first get into the AutoCAD program you may start to draw immediately. You do not need to give a name to the drawing you are working on until you first save it to the hard disk. As soon as possible after beginning a new drawing you should "SAVE" the drawing to the hard drive of the computer. In the process of saving for the first time, you will be required by the program to give the drawing a name. I recommend that you name all of your drawings with a name beginning with the date in year, month and day of the month format, such as "2009 03 01 exercise 1.dwg". You cannot give your drawing a filename extension, because the program automatically gives it an extension of "DWG." The icon on the toolbar that looks like a floppy disk is the "Save" button.
Once you begin the AutoCAD program, you are considered to be in a so-called "Drawing Session." A "Drawing Session" may last from a few minutes to several days. As long as the computer is turned on and as long as you do not close down the program, you continue to remain in the same "Drawing Session," although you may begin one or more new drawings and/or revise one or more existing drawings during that "Drawing Session." You can begin a new drawing if you are already in the AutoCAD program by using the "NEW" command. You can edit an existing drawing in AutoCAD by using the "OPEN" command. The advantage of remaining in a "Drawing Session" without closing out of AutoCAD is that there are settings which remain set across the "Drawing Session" no matter what drawing you are editing. For instance, the setting of the aperture size and the state of "grips" will go across drawings and remain set within a 'Drawing Session."
The following commands are located in the first pull-down menu, called the "File" menu, and are used to start and save drawings:
"Open" This command will bring up a dialogue box which will be a list of all drawing files in the current logged subdirectory (the C:\student subdirectory), to permit you to select a drawing from the list by "double-clicking" on the name. It will exit you from the drawing you are in first. If the current drawing from which you are exiting has been changed since the last time it was saved, you will be prompted to "Save" the changes, or "Discard" the changes.
"Save" This command will save the current state of the drawing to the hard disk under the name you have given it. If you have not yet given it a name, you will be prompted for one. Just type in a name (no extension) and then <RET>.
"SaveAs" This command will save
the current state of the drawing to the hard disk, like the "save" command,
but you will be prompted for a new name for the drawing. Once this command
has been executed and a new name has been assigned to it, the current drawing
will continue to be named that same name, until you change it again. For
example, if you name a drawing FEH1 in response to the first "SAVE" command,
then you select the "SAVEAS" command, you will be prompted for a new name.
If you then were to name the drawing FEH2, that would be the name of the
current drawing. The drawing FEH1 would still exist on the hard disk, but
would not be saved or updated subsequently as you continue to work on FEH2.
Furthermore, when you select the "SAVE" command next, the drawing FEH2
will be updated on the hard disk, but not FEH1. Through this simple command,
you could create several sequential versions of the same drawing for future
AutoCAD always makes a duplicate drawing file of your drawing whenever the "Save," "SaveAs" or "Exit " commands are selected. This backup has a special filename extension, named "BAK," instead of "DWG." The contents of the "BAK" file is the same as the last time you saved the drawing, previous to this time. If you wanted to edit the "BAK" file, you must make a copy of it to a new filename with the "DWG" filename extension.
For instance, if 2009 03 01 exercise 1.DWG has been saved, there is also a file called "2009 03 01 exercise 1.BAK" in the same folder on the hard drive. If you want to look at 2009 03 01 exercise 1.BAK, or change it, you must copy it to a file which has a DWG filename extension. You can do this using the Windows Explorer.
Because electronic media and computers in general are not totally safe from crashes or corruption of files, a foolproof "belt-and-suspenders" backup system or systems for preserving your work must be implemented.