Transcript Input Output, Etc and Boot Process PowerPoint

IT Chapter 2 Part A
How Computers
Work
2.1.1Input, process, output,
and storage
• The operating system helps the computer
perform four basic operations, which include
input-process-output-storage
• Input – Recognizing input from the keyboard
or mouse
• Processing –- Manipulating data according
to the user's instructions.
• Output – Sending output to the video screen
or printer.
• Storage – Keeping track of files for use later.
Usually saved on hard drive or floppy
2.2The Boot Process
2.2.1Initializing and testing
the system hardware
• For an operating system to run, it must
be loaded into RAM
• When a computer is first turned on, it
launches a small program called the
bootstrap loader that is built into the
computer's hardware
• hence the term "booting" the computer
Power-on self-test (POST)
• To test the computer's hardware, the bootstrap
program runs a program called power-on self-test or
POST
• In this test, the computer's Central Processing Unit
(CPU) checks itself first and then checks the
computer's system timer
• If the POST finds errors, it sends a message to the
computer monitor. If the POST finds errors that
cannot be displayed on the monitor, it sends errors in
the form of "beeps."
• The POST sends one beep and the screen begins to
display OS loading messages once the bootstrap has
determined that the computer has passed the POST
2.2.2 Loading the operating
system and hardware
configuration
• The next step for the bootstrap program is to locate
the OS and copy it to the computer's RAM
• The bootstrap loader first looks to see if the OS boot
file (or boot record) is located on a floppy drive. If not,
it looks for it on the hard disk . Its order can be changed
in the system BIOS setup.
• When the bootstrap finds the OS, it looks for a file
called the boot record. The boot record is copied to
the computer's RAM and the bootstrap program then
turns over the control of the boot process to the boot
record.
• The last step of the boot process is for the OS to find
hardware configuration files that are specific to the
computer
2.2.3The boot sequence
• The number of events that happen in the boot
process depends on whether you are doing a
cold boot or a warm boot.
• The cold boot involves many more events
and bootstrap (BIOS) activities than the warm
boot. The cold boot causes the BIOS to guide
the computer's boot sequence through a
series of steps that verify the system's
integrity