DOS Level 1: SOFTWARE: Sets of programs (stored sets of instructions) that govern the operation of computer system and make the hardware run. These programs (instructions) tell the hardware how to perform a particular task such as word processing, games, database management, etc. DOS --- DOS - Disk Operating System - is a piece of software. However, it is different from most software because a computer cannot run without it. It is the first piece of software that is installed in RAM every time the computer is turned on. When the user first starts the computer, the DOS files must be available in either the A drive or on a Hard Disk. The computer finds the desired DOS files and automatically loads them into RAM. This process is often called "BOOTING" the computer -from the computer pulling itself up by its BOOTstraps. TO LOAD DOS ----------- "Cold" Boot: Turning the computer on "Warm" Boot: The computer has already been started, but you wish to completely "clean-out" RAM and re-load DOS. This is a much faster method of re-starting the computer since it skips the usual system checks. To accomplish, you press three keys simultaneously: -- DOS performs 2 functions: 1. Links the Hardware 2. Allows for file management We think of most software as enabling us to create something - like a document or a spreadsheet. DOS's mission is vital. Firstly, it enables the hardware devices to properly communicate with each other. It is a set of instructions so that the computer's brain understands how its arms and legs operate (keyboard, monitor, printers,...). We take this ability for granted. It is like starting a car - many complex systems must work in unison for it to work, yet we take it for granted that it will start. The second function of DOS is also important. We must have a means to manage the files that we save on our Floppy Disks or Hard Drives. There are times when we wish to copy these files from one disk to another, or erase them, or determine which files are on a disk. These tasks are performed often and the software required to do so is DOS. When DOS has been properly loaded from either a Floppy Disk or a Hard Drive, the familiar "DOS Prompt" will appear. This prompt will look something like this: A> This symbol signals 3 things: 1. DOS has been properly loaded into RAM 2. "A" is the DEFAULT drive 3. Awaits a DOS file management command Each disk drive and hard disk has a letter associated with it. If a drive is considered the DEFAULT drive, then the computer will always assume that the information needed is in that drive, OR if something you have created is saved - it will be saved to that drive, UNLESS you tell the computer otherwise. All types of disks contain files. We use DOS as a software tool to manage these files. We not only tell the computer which file we want to erase or copy but also which drive it is currently in. DOS FILE CONVENTIONS -------------------- FILES: Any related set of instructions - programs, documents, spreadsheets, etc.. A floppy disk is like a file cabinet with each folder representing files on the disk (in the cabinet). Rules: filename | extension (optional) | 1-8 Characters | 1-3 Characters No Spaces | No Spaces Letters/Numbers| Letters/Numbers If an optional extension is used, a period is used to separate the filename and extension. Many characters are allowed in filenaming. The following are INVALID for filenames OR extensions: . " / \ [ ] : | < > + = ; , Each file has a name. When you want DOS to act on a file, you must specify its proper name (including its extension if applicable). A file's name is made up of a filename and an optional extension: saledata.jly ³ ³ ÀÄÄExtension (optional) - UP TO 3 CHARACTERS ³ ÀÄPeriod required as Separator IF extension used ÀÄÄFilename - UP TO 8 CHARACTERS Some filenames: SAMPLE SAMPLE.DOC BUDGET.WK1 Two files with the same exact name CANNOT exist on the same disk or subdirectory (subdirectories are covered under hard disk sections). FILESIZE -------- Computers use 1 BYTE to represent 1 character such as a letter of the alphabet, a number, a punctuation mark, a space, etc. A BYTE is also a unit of measure since it represents 1 character. We measure the size of RAM in Bytes, as well as the size of Files/Programs in Bytes. We also measure the capacity of Disks and RAM in Bytes. So many Bytes can be contained on disks or RAM that we talk about: KILObytes = 1,000 bytes (often abbreviated "k") MEGAbytes = 1,000,000 bytes (often abbreviated "meg") 5.25" disks Double Sided, Double Density = 360k Double Sided, High Density = 1.2meg 3.5" disks Double Sided, Double Density = 720k Double Sided, High Density = 1.4meg Hard Drives = 10meg, 20meg, 30meg, 40meb, 60meg,......350meg FREQUENTLY USED DOS COMMANDS ---------------------------- When DOS is booted, a copy of INTERNAL DOS commands are placed in the computer's memory (RAM). These are called INTERNAL commands because they stay in RAM until the computer is turned off. To use these commands you do not have to re-insert the DOS diskette. The rest of the commands on the DOS disk are called EXTERNAL commands because they are NOT read into RAM when you boot DOS. Rather, to use them DOS must accessible in one of the disk drives. The following are some frequently used DOS commands: INTERNAL ³ EXTERNAL (Insert DOS in Drive A) ³ DIR TYPE ³ FORMAT CHKDSK COPY CLS ³ DISKCOPY ERASE DATE ³ COMP RENAME TIME ³ DISKCOMP **-- Internal DOS Commands - A>DIR B: - To find out what files are on a diskette in the specified drive (B in this example). If just DIR is typed and entered, a listing of files in the default drive (A in this case) will be displayed. A>DIR B:/P - Displays list of files one screen at a time A>DIR B:/W - Displays list of files using the entire width of the screen NOTE: The /P and /W options shown above for the DIR command are called command switches. Most DOS commands have a variety of switches to alter the core command. A>COPY A:filename.ext B: - To copy one file from Disk A to Disk B instead of an entire diskette. A>DEL B:filename.ext - To remove the specified file(s) from the disk in the specified drive. A>DATE - To change the system date. This date will be "stamped" on each file created or edited. A>TIME - To change the system time. A>CLS - To clear the screen **-- External DOS Commands - DOS Disk required in Drive A or Hard Drive A>FORMAT B: - Prepares a new disk in Drive B for use on the IBM PC. If an old disk is used, it will erase its contents. (Follow on- screen directions) A>FORMAT B:/S - Same as above, BUT ALSO Installs the INTERNAL DOS commands on the new disk. Thus, this disk is now capable of starting the machine. A>CHKDSK B: - Indicates the number of files and amount of free storage space remaining on the disk in drive B. It also indicates the amount of RAM storage. A>CHKDSK A: /F - Fix any problems that CHKDSK finds (converts lost clusters to *.CHK files which can later be deleted) A>DISKCOPY A: B: - Making an exact copy of the diskette in Drive A onto the diskette in Drive B. (Follow on-screen directions) Remember, if the computer is not told differently, it will assume the DEFAULT drive: A>COPY A:sample.wk1 B: is the same as: A>COPY sample.wk1 B: The "A:" in the first example is redundant. ***** END OF FILE: Press to return to Main Menu *****