BA 103--Computers and Information Systems
List of Concepts

Dr. Bud Banis, 314-516-6136, CCB 230
Off-campus, 636-394-4950  E-mail

System Software

The Disk Operating System (DOS)

    What happens when you start up your computer:
  1. The processor finds instructions about the specific machine in ROM and checks that all the basic parts are in place. ROM is nonvolatile and information can only be changed by changing the chips.
  2. CMOS memory is consulted to identify device addresses and types, such as how much memory, time and date, important information about secondary storage devices (e.g. the hard drive). Information in CMOS can be changed, but is maintained by a battery.
  3. The boot drive is surveyed to find operating system software (DOS & BIOS). Resident parts of the operating sytem software are loaded into memory.
  4. CONFIG.SYS and AUTOEXEC.BAT files are executed to install drivers for devices and define environmental setup factors. These are editable files on the boot disk.
  5. The AUTOEXEC.BAT can be used to define a program(s) run at startup. For example, many computers are now set up to start WINDOWS right away
Testing for Viruses
Check your operating manual and virus testing software to do this correctly.
A good website to visit on this is the Symantec Antivirus Research Center at
you might also want to check for more information and a free copy of their anti-macrovirus software

Terms and concepts you should know:

Computer System = everything, including the people, involved in processing specific Information or performing a task. High bit low bit

Campus office CCB 230
On-campus phone X6136
Off-campus 636-394-4950
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last modified August 18,2002 ~~ comments and suggestions to