Working in DOS

1. Working in DOS • DOS is a true operating system • An operating system does 4 things: • it must communicate with the hardware • it must create a user interface • must allow users to use and manage programs • must allow users to add, move and delete the installed programs

2. DOS • Until version 5.0 you could only get DOS on a PC and not off the shelf • Memorize chart on page 520 • Files in DOS- • Filename no longer that 8 characters • Extension up to 3 characters • No spaces in filename or extension • Cannot use /\[]<>+=;,*? • REMEMBER WIN 95/98 DOES HAS 255 CHARACTER LIMIT

3. DOS • DOS cannot support more than 2 floppy drives • Files organized into directories and subdirectories (folders in Windows) • Exact location of file called its path • Anything not in directories is in the root directory

4. 3 Main Files of DOS • THESE FILES MUST BE ON COMPUTER OR IT WON’T BOOT! • IO.SYS- handles talking to BIOS and hardware • MSDOS.SYS-primary DOS code, the kernel • COMMAND.COM-interprets commands, called command interpreter, displays DOS prompt • These files not interchangeable on different versions of DOS

5. DOS commands • ATTRIB- changes attributes to either read, system, hidden or archive • DELTREE-deletes a directory and its subdirectory and all their files • CD- changes directory • MD- creates directory • DIR/W- to see files in wide format

6. MORE DOS • Wildcards- use a * to find all files with similar text, example- *.com to find all files that end in .com. The ? Symbol can be used to find matches for individual characters • Deleting- done with the DEL or ERASE commands • Copying- COPY • Moving- MOVE

7. Config.sys in DOS • Following found in Config.sys used in DOS for • device drivers • buffers= statement (buffers are a temporary assembly area for files in memory) • stacks= statement allows CPU to set aside registers • files= statement how many file handles

8. Sample CONFIG.SYS file Device=C:\DOS\HIMEM.SYS Device=C:\DOS\EMM386.EXE 1024 RAM FILES=30 BUFFERS=15 STACKS=64,500 DEVICE=C:\DOS\SMARTDRV.SYS 1024 DOS=HIGH, UMB DEVICEHIGH=C:\MOUSE\MOUSE.SYS DEVICEHIGH=C:\DOS\RAMDRIVE.SYS 4096/a

9. AUTOEXEC.BAT • Another way to support devices is through TSR’s (terminate and stay resident) programs. These are located in Autoexec.bat. One of the most common TSR’s is for mice • DOSKEY.COM- is a TSR that keeps track of commands • MODE command changes look of monitor • SHARE command prevents file from being used by more than one program

10. DOS commands • SET command creates environmental variables so DOS programs can read them • PATH- command tells user where to look for file when not found • PROMPT- determines what prompt looks like

11. Using Commands for Drives in DOS • FDISK- partitioning • FORMAT- high level format • VOL- see the volume label of drive • SYS- copies 3 system files to partition making it bootable. Can make bootable floppies with it • LASTDRIVE- allows for memory allocation beyond the 2 extra drive letters beyond C

12. Checking Drives • CHKDSK- identifies and repairs lost cluster chains. Will identify but not repair cross linked files (2 files trying to claim same cluster) • SCANDISK- repairs lost clusters, cross linked files, directory and file structures, file allocation tables, even volume labels • DEFRAG-

13. Smartdrv • Initiated from the autoexec.bat file • Is a software disk cache • When run with /s will tell you efficiencly of disk cache • Page 558 and 559 gives possible command combinations