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