MS-DOS

*help

This command gives you a key to virtually everything you need to use DOS effectively. Can't remember the format for the FORMAT command? Not a problem! Type HELP FORMAT and press the ENTER key, and you've got everything you need to use FORMAT! This is true for virtually every DOS command so if you remember HELP command name you won't have any problems.

Another way to get help (or, if you don't install the HELP files suggest above, the ONLY way to get help in Windows 95) is to use /? (slash, question mark) after any command. This is faster and sometimes a more useful form of help, but it is generally only a listing of options. HELP is usually a more verbose help facility than /? is.

*copy

Once you know where to get help, the rest is easy. The whole purpose of DOS is to let you get around the directory tree easily. You use DOS to start applications (like my own P11.EXE program) and to copy files, delete files, build places to put files, and compare files, and so on. Files, Files, Files. That's what DOS is really for.

The #1 tool for file handling is the COPY command. Specify the "from" file first, then the "to" file. COPY only copies from within one directory at a time, but the "to" directory can be different. For copying entire directory structures, use XCOPY instead.

What makes COPY so powerful is that you can use "wild cards" like * and ? within the file name.

*xcopy

Like COPY, XCOPY can use wildcards to copy a file or group of files to another directory. But XCOPY is more powerful because it has the ability to copy an entire directory structure in one command. Use the /s option to accomplish this. Use HELP XCOPY to learn more, of course!

*cd

CD is the cold, hard way of doing things, but sometimes it's the right way. What makes it cold and hard is that in comparison to Norton's Change Directory (normally abbreviated NCD, but I abbreviated it to C on my system), the DOS CD command requires you to type the complete directory entry, all the way back to the root level! This is absurd. NCD, on the other hand, lets you type in anything that's close, and it will search your entire directory structure and plop you down right where you want to be. For example, to go to the \p11\pumps\svgapump directory, I can just type in: c svgap and immediately NCD will take me there. With CD, I would have to type cd \p11\pumps\svgapump to accomplish the same thing. Saving keystrokes is the name of the game. (That's why later in this tutorial, you'll learn to write batch files.)

Its regarding disk scheduling in any OS..

When a process wants to do disk I/O, it makes a call to the operating system. Since the operation may take some time, the process is put into a blocked state, and the I/O request is sent to a part of the OS called a device driver. If the disk is idle, the operation can be started right away, but if the disk is busy servicing another request, it must be added to a queue of requests and wait its turn. Thus the total delay seen by the process has several components:

• The overhead of getting into and out of the OS, and the time the OS spends fiddling with queues, etc.
• The queuing time spent waiting for the disk to become available.
• The latency spent waiting for the disk to get the right track and sector.
• The transfer time spent actually reading or writing the data.

MS-DOS (short for MicroSoft Disk Operating System) is an operating system for x86-based personal computers, which was purchased by Microsoft. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for personal computers during the 1980s up to mid 1990s. It was preceded by M-DOS (also called MIDAS), designed and copyrighted by Microsoft in 1979. MSDOS was written for the Intel 8086 family of microprocessors, particularly the IBM PC and compatibles. It was gradually replaced on consumer desktop computers by operating systems offering a graphical user interface (GUI), in particular by various generations of the Microsoft Windows operating system. MS-DOS developed out of QDOS (Quick and Dirty Operating System), also known as 86-DOS.

MS-DOS development originally started in 1981, and was first released in 1982 as MS-DOS 1.0. Several versions were released under different names for different hardware. MS-DOS had eight major versions released before Microsoft stopped development in 2000. It was the key product in Microsoft's growth from a programming languages company to a diverse software development firm, providing the company with essential revenue and marketing resources. It was also the underlying basic operating system on which early versions of Windows ran as a GUI.

Hidden files are files stored on the disk, but which do not show up when you list a directory of the disk.

In DOS, you normally type the command DIR to view the files on a disk. If you would like to see hidden file names, use the command DIR /AH (A=Attribute; H=Hidden).