DOS is short for Disk Operating System. It is the name for a number of closely related operating systems that came standard with nearly all IBM PC compatible computers from 1985 to 1991. Even as late as 2000, Microsoft operating systems such as 95, 98 and ME were partially DOS-based. The allure of DOS is that it has a command-line interface that is incredibly fast and easy to work with. There is some specific terminology that will help you make the most of DOS.
MS-DOS, PC DOS, DR-DOSWhile DOS is usually shorthand for MS-DOS (Microsoft Disk Operating System), there are numerous other flavors. Some of these are MS-DOS, PC DOS, DR-DOS, FreeDOS, PTS-DOS, ROM-DOS and JM-OS. All DOS-type operating systems run on x86 Intel-compatible CPUs, mainly IBM PC and compatibles.
Autoexec.bat and config.sysMS-DOS and early versions of Windows such as 3.x use the autoexec.bat and config.sys files to centralize the loading of files that various devices and the operating system need to run properly. These files are most commonly edited by using the EDIT command in MS-DOS.
Batch filesBatch files are text files, ending in the extension *.bat, that contain a series of commands to be run by the operating system. In DOS, a shell program (usually COMMAND.COM or cmd.exe) reads the file and executes its commands line-by-line. Batch files are an excellent way to automate tedious tasks.
Hard disk partitionsDOS had an upper limit as far as partition size, mostly due to the fact that it didn't support any file system newer than FAT16. FAT16 wouldn't allow hard disk partitions larger than 2.1 gigabytes.
8.3 filenamesBecause it used the FAT16 file system, DOS required use of what is known as 8.3 filenames. This means that filenames in DOS are restricted to eight characters and filename extensions are restricted to three.
Command line interfaceAll DOS systems use a command line interface. This means programs are started by entering their filename at the command prompt. Running programs from the command line requires fewer keystrokes and is generally much faster than operating through a graphical user interface or GUI.
Stephen Gilbert has written an excellent guide to using the DOS command line interface. AnimatedSoftware.com has a glossary of vital DOS commands.