Chapter 7 Operating System Fundamentals

1. Chapter 7Operating System Fundamentals

2. The Multi-Process System • Multi-User: The ability to appear to give resources to more than one concurrent user • Multi-Task: The ability to appear to have more than one program running at the same time • Multi-Processor: The ability to split a task among multiple CPUs.

3. DOS Boot Sequence • BIOS POST (Power-On Self-Test) • BIOS, along with programmed CMOS, identifies major I/O components • BIOS checks boot sector (MBR) • IO.SYS & MSDOS.SYS loaded to RAM • IO.SYS checks CONFIG.SYS • COMMAND.COM loaded to RAM • AUTOEXEC.BAT is executed • DOS command prompt appears

4. Additional Startup Sequence for Win9x • Win.com executed • Kernel32.dll and kernel386.exe loaded; they contain the win9x care and device drivers • Gdi.exe and gdi32.exe loaded; they manage the hardware devices • User.exe and user32.exe loaded • The registry (user.dat and system.dat) is read • Fonts are loaded • The WIN.INI and SYSTEM.INI files are read; they are for backwards compatibility • The shell is started

5. Typical CONFIG.SYS Config.sys is responsible for: Setting up memory management Configuring DOS for use with devices and applications Loading device driver software and installing TSRs Typical settings include: • DEVICE=C:\DOS\HIMEM.SYS • Loads extended memory (>1024KB) driver • DEVICE=C:\DOS\EMM386.EXE • Allows conventional memory programs to the upper memory area (640-1024KB) when they are defined with DEVICEHIGH= instead of DEVICE= • FILES=30 • Sets the number of concurrent files that can be open at any time

6. CONFIG.SYS (cont.) • BUFFERS=15 • Each buffer is 15 blocks of RAM set aside for storing data being transferred to/from disk • STACKS=9, 256 • Establishes the number and length of special RAM memory storage operations • DEVICE=C:\DOS\SMARTDRV.SYS 1024 • One method of establishing a disk cache in RAM • DOS=HIGH,UMB • Moves the DOS kernel into upper memory • DEVICEHIGH=C:\MOUSE\MOUSE.SYS • One method of activating mouse services in DOS • DEVICEHIGH=C:\DOS\RAMDRIVE.SYS 4096 /a • Creates a virtual/volitile disk drive in memory • INSTALL=C:\DOS\SHARE.EXE • One method of allowing files to be shared on networked or multi-task systems

7. AUTOEXEC.BAT Autoexec.bat is a batch file that is used to execute programs after the command kernel has been started • DATE • Displays and allows setting of the system date by the user • TIME • Displays and allows setting of the system time by the user • PROMPT=$P$G • Sets the command prompt to a defined ASCII string • SET TEMP=C:\TEMP • Sets the directory used for temporarily holding data • PATH=C:\;C:\DOS;C:\MOUSE • Sets the directories that are included in the kernel’s command search • SMARTDRV.EXE 2048 1024 • Displays and allows setting of the system date by the user

8. DOS Memory Model • Conventional • 0-640KB • Upper • 640-1024KB • Extended • >1024KB • Current technology • Directly addressable • Expanded • 1024KB-32MB • Older technology • Page framing of 16KB modules • Virtual • Swap file on hard drive • Consists of contiguous clusters on the hard drive • Can be temporary, fixed, or variable

9. Rules of DOS Filenames • 8.3 rule • 8 characters for the file name • 3 characters for the extension • Separated by a period • Characters not allowed: [ ] : ; + = \ / , * ? | < > • Each file must have a unique path • C:\documents\temp\schedule.txt • C:\documents\temp\examsch~2.txt

10. Rules for Win9X Filenames • Filename255.extension3 • WinME & Win2K are limited to 215.3 • This is due to the CDFS filename limitation • Characters not allowed: : \ / * ? | < >

11. Disk Structure • Low-level format • Done at the manufacturer • Sets the tracks, cylinders & sectors • Partition • FDISK command • High-level format • FORMAT command

12. Disk Partitioning

13. The FAT File System

14. File System Comparison*This is a vast oversimplification

15. Common File Extensions

16. File Extensions (cont.)

17. File Extensions (cont.)