What are Boot Disks

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WHAT ARE BOOT DISKS AND WHY WOULD I NEED ONE!

A Program is a set of instructions for the computer.

Software  is  a  program  or  group  of  programs to tell  the computer how to function.

The  operating  system  is  a set of instructions telling  the computer how to interface (hookup or communicate) with its input and output devices and any other parts of its system.  Recent types of operating systems on  microcomputers are MS DOS  (Micro‑Soft  Disk  Operating  System),  OS2, UNIX, and Macintosh OS, Linux, Windows 9X (95, 98), Windows NT or 2000, and Windows ME (Millenium). The majority of IBM PC's  and  compatibles in the past used MS DOS or PC DOS (a special version of MS DOS for IBM's only).  Currently they use Windows 9x, (9x=95, or 98, etc.), ME, or Windows NT.  Some systems use UNIX, and Linux is also becoming increasingly popular in certain situations where the PC does not need access to large software selections.  If your computer does not have an OS or your Boot Device is damaged it can not run.  This can happen if it is new or has had a virus or other problem.  In this case you will have to have a boot disk to start it.

WHAT HAPPENS WHEN YOU START YOUR COMPUTER

A Computer normally starts with the following procedure:

Your turn the switch On

The Power Supply sends power to Motherboard

ROM Chips do POST (Power on Self Test)

I/O (Input/Output) Set up occurs (PCI Plug and Play devices, such as modems, etc. are configured)

System seeks MBR (Master Boot Record) from the Boot Device or Devices (CD ROM, Hard Drive, Floppy, etc.)

If none found on boot device system stops and says

          "NON SYSTEM DISK OR DISK ERROR

                REPLACE AND STRIKE ANY KEY WHEN READY"

(Or something similar)

IF MBR is Found then instructions there are executed and they put a secondary loader in RAM

Secondary Loader finds IO.SYS and MSDOS.SYS or other system files and carries out their instructions.  Which usually leaves them into memory

They usually Load other device drivers, for example DOS checks for CONFIG.SYS

IF FOUND system reconfigured as told

DOS Loads COMMAND.COM

Checks for AUTOEXEC.BAT in root

IF Found command.com carries out commands found.

IF Not Found Command.com displays date and time prompts.

 

Modern BIOSes allow booting from many different devices.  This is configured in the BIOS setup of the computer. When a boot device does not have an Operating System, for example when a formatted floppy without and OS is in the A drive when an IBM PC compatible computer starts the computer tries to read the disk, but does not find the instructions it needs to continue operation.  As a result it displays something like:

 

"NON SYSTEM DISK OR DISK ERROR

REPLACE AND STRIKE ANY KEY WHEN READY"

 

on the screen, and waits for you to do something.  At this stage you must either remove the device or replace it with one with an OS or go into the BIOS and change the boot procedure.   If you do either, the computer will read the necessary instructions and then begin normal operations.

For instructions of how to make a boot disk

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