Black Box 4

home *** CD-ROM | disk | FTP | other *** search

/ Black Box 4 / BlackBox.cdr / dosutils / primer31.arj / MRDOS6.TXT < prev next >

Wrap

Text File | 1992-03-12 | 11.0 KB | 270 lines

----------------------------[ HARD DISK LEVEL 1 ]----------------------------- HARD DISK DRIVES ---------------- Also called Hard Drive, Hard Cards, Fixed Disk Drives. Hard Drives are essentially large floppies housed within the computer. They are much faster, have much higher capacity, and are less likely to fail due to the safe environment from within which they operate. Hard Disk cost is related to its capacity and its Access Time. Access Time is the amount of time it takes the disk to locate a random piece of information. Access Time is measured in milliseconds (ms-thousandths of a second). A fast one would be 28ms, a slow one 65ms. DOS Disk Operating System (Director Of Services) --- A quick review of some DOS concepts discussed earlier is in order. DOS it the master control program for the flow of information within a PC. One of its primary functions is to oversee all hard disk activities - reading/writing information from/to a disk and loading/executing programs. It controls (links) all hardware devices so they may communicate with one another including: Floppy Drives: 5.25", 3.5" Hard Drives: 20meg, 40meg +..... Ram Disk: Simulates a disk drive from within RAM Laser Disk: "CD's" for computers Tape Storage Device: Backup system typically using cassette type tapes PLUS, Screen, Keyboard, Printer, Modem, Mouse, ... As if this wasn't enough, this modest software called DOS also keeps track of the current time and date, and the usage of all memory locations within RAM. Once DOS has been properly BOOTed, you will see the familiar "DOS Prompt": A> This says: 1. DOS has been properly installed 2. "A" is the default drive 3. DOS is awaiting your next command DOS REALITIES ------------- There are three types of FILES that may be successfully "executed" from the DOS Prompt: 1. *.EXE Commands ("EXECUTE" Program files Lotus, dBASE, etc.) 2. *.COM Commands ("COMMAND" Program files Lotus, dBASE, etc.) 3. *.BAT ("BATCH" Custom programs) To successfully execute one of the *.EXE, *.COM, or *.BAT command files, the file itself must be either: 1. In the Current directory 2. Within a directory that is part of the DOS "PATH" command Batch (.BAT) files are the only executable files you can write using a simple word processor or DOS's built-in Line Editor (EDLIN) - more later. BOOTING (or Bootstrap) ------- To load and execute the Disk Operating System "DOS". This term comes from the phrase "pull yourself up by your own bootstraps". This happens within a PC when it is turned on. Actually, a built-in program (ROM) is executed, next a couple of "hidden" files from the ROOT directory (hard drive) or DOS Disk (floppy disk), then COMMAND.COM (DOS internal command interpreter) is followed by the Optional CONFIG.SYS and AUTOEXEC.BAT files. COMMAND.COM: Must be loaded for DOS to operate properly; it contains the Internal DOS commands including those used most often: COPY, DIR, DEL, etc. The remainder of files on the DOS disk are called External Files (DISKCOPY, CHKDSK, etc.). To utilize one of these commands, the DOS disk must be accessible. CONFIG.SYS: Optional. If it is located on the Disk that you are BOOTing from, DOS will "open" it and read and interpret a list of system configuration commands. This is an ASCII text file which can be created by any text editor. Some configuration commands are: FILES, BUFFERS, and DEVICE. AUTOEXEC.BAT: Optional. An ASCII text file. A "batch" file. A set of DOS commands and other special commands. "Opened" and read after CONFIG.SYS, IF it exists on the BOOT disk. SOME FREQUENTLY USED DOS COMMANDS WITHIN A HARD DISK ENVIRONMENT ---------------------------------------------------------------- A Hard Disk is just like a floppy. However, due to its size, additional file management commands are needed. The following can also be used on floppy disks, but they are most commonly found in Hard Drive environments. INTERNAL │ EXTERNAL (Insert DOS in Drive A) │ MD │ CHKDSK CD │ BACKUP RD │ RESTORE PROMPT │ SUBST PATH │ TREE **-- Internal DOS Commands - MD - Make a directory (see below) CD - Change to a directory (see below) RD - Remove a directory - must be rid of files first (see below) PROMPT $p$g - Changes the way the DOS prompt is display. $p$g insures that the current directory is shown at the prompt. Very useful. Usually "set" in the AUTOEXEC.bat file (see below) PATH=c:\DOS;c:\BATCH;c:\UTILITY Sets up a command (*.EXE, *.COM, *.BAT) search path in the DOS environment. When a command is issued from the DOS prompt, it first looks in the directory you are currently in, then looks in each directory noted on this path. Usually this command is built into the AUTOEXEC.bat file (see below) **-- External DOS Commands - CHKDSK C:\*.* /F Checks the integrity of disk files - the level of fragmentation of files. Indicates the number of files and amount of free storage space remaining on the disk in drive A. It also indicates the amount of RAM storage. If any lost clusters are found (data without a home), they can be converted to *.CHK files so you can delete them to free up the disk space. SUBST E: C:\LOTUS\123FILES - Assigns a 1-letter drive ID (E) to a directory path SUBST E: /D - Cancel previous designation TREE - Displays a list of all subdirectories on the drive TREE /F - Displays a detailed list of all subdirectories and all files on the disk. BACKUP (see Hard Disk Level 2) RESTORE (see Hard Disk Level 2) DIRECTORIES ----------- As previously mentioned, a hard disk is essentially a large floppy disk. However, it offers some distinct advantages: Is much larger Stays inside the machine Operates (transfers data) at a much higher rate (5-10 times) Because a Hard Disk is so much larger than a floppy, we use an additional file organization tool called SUBDIRECTORIES. If a floppy is like a filing drawer, then a Hard Drive is like a group of file drawers, each drawer call a SUBDIRECTORY. DOS lets you organize files using tree-structured directories rather than a single directory. In other words, since a 20 meg (20,000,000 byte) capacity hard drive can contain approximately 60 floppy disks worth of files, an additional organization tool is needed. The creation of SUBDIRECTORIES allow us to subdivide a disk to contain related files. It's as if we have many file cabinets available to store our files rather than a single giant one. DOS permits up to 112 files on a floppy disk (360k). However, with that many it is tedious to examine via a DIR command and it also slows DOS's file access and retrieval. ROOT DIRECTORY - Main directory. It contains all the subdirectories. It also provides support for all the SUBDIRECTORIES. Each SUBDIRECTORY can contain files as well as other SUBDIRECTORIES. These other Subdirectories could be thought of as SUB-SUBDIRECTORIES. With floppy disks, to use a file in a different drive, we would specify the drive and filename (B:Filename.ext). Similarly, if we want to access a file in a SUBDIRECTORY we specify a PATH, OR make that SUBDIRECTORY the "current" one. ┌──────────────┐ │ROOT DIRECTORY│ │ │ │ files│ └──────┬───────┘ │ ┌────────────────────┼────────────────────┐ │ │ │ ┌──────┴───────┐ ┌──────┴───────┐ ┌──────┴───────┐ │SUBDIRECTORY │ │SUBDIRECTORY │ │SUBDIRECTORY │ │ files│ │ files│ │ files│ └────────┬─────┘ └──────────────┘ └──────┬───────┘ │ │ ┌─────┴──────────────────┐ │ ┌──────┴───────────┐ ┌─────────┴────────┐ ┌──────┴───────────┐ │"SUB-SUBDIRECTORY"│ │"SUB-SUBDIRECTORY"│ │"SUB-SUBDIRECTORY"│ │ files│ │ files│ │ files│ └──────────────────┘ └──────────────────┘ └──────────────────┘ PATH: A PATH specifies the names of the subdirectories that DOS must go through from the ROOT DIRECTORY to get to the file. The directories are separated by a back slash ( \ ). (NOT the same as the DOS PATH command noted above) EX: C:\123FILES\PROJECTX\BUDGET.WK1 C:\ Root Directory │ ├─ 123FILES Lotus files Subdirectory │ └──┬── PROJECTX Sub-Subdirectory containing all "PROJECTX" files │ └───── BUDGET.WK1 A specific Lotus file called BUDGET within the PROJECTX Sub-Subdirectory DOS COMMANDS & SUBDIRECTORIES: There are only 3 key commands in dealing with Subdirectories: MD, CD, and RD TO MAKE A SUBDIRECTORY ---------------------- MD dirspec - Internal - to Make a Directory -dirspec is the name of the subdirectory or its PATH EX: C>MD 123FILES <ENTER> - This creates a subdirectory called 123FILES - Naming a SUBDIRECTORY follows the same rules for file naming, except extensions are not used - You can create an unlimited number of SUBDIRECTORIES - Identical Filenames can exist in different SUBs (Remember, 2 files with identical filenames CANNOT coexist in the same SUBDIRECTORY) TO CHANGE THE "CURRENT" SUBDIRECTORY ------------------------------------ The computer can only have 1 "file drawer" open at a time - thus this is called the current directory. Unless instructed otherwise, the computer will assume all files sought and sent will go into this current subdirectory. CD\dirspec - to Change the "current" Directory - EX: C>CD\LOTUS <ENTER> - This makes a subdirectory called LOTUS the current one TO REMOVE/ERASE A SUBDIRECTORY ------------------------------ 1. First make this directory the current one C>cd/dirspec 2. DELETE all the files within this directory C>DEL *.* It will ask if you are sure - Y 3. Go to the ROOT DIRECTORY C>cd\ 4. RD dirspec - Remove Directory C>RD dirspec ***** END OF FILE: Press <ESC> to return to Main Menu *****