"/home/yossef/notes/Su/os/study_os_l1.md"

path: Su/os/study_os_l1.md

- **fileName**: study_os_l1
- **Created on**: 2025-03-09 00:06:21

what is an os(operating system)?

is a program that acts like intermediary between the user of computer
and computer hardware

what is operating system goals?

1. execute user program and solve problem easier
2. make the computer system convenient to use
3. use computer hardware in efficient way

computer systems divided into four components

• hardware
• operating system
• application program
• users

what is os resource allocator?

• manage all resource of computer hardware
• and decided between requests for efficient and resource utilization

what is os control program?

It controls execution of program and prevent errors

what is kernel?

It's the one program running at all times on the computer

what is bootstarp program?

It's a program loaded in power up or reboot

• typically stored Rom EPROM known as fireware
• installation all aspects of system (hardware, software)
• loading operating system kernel

what is interrupt?

General transfers control to the interrupt service routie(ISR) through
interrupt vector which contains the address of all service routines

what is trap or exception??

Is a software generated interrupt caused either by error or a user request

what is polling?

The cpu constanlly checks status of device and if it's need cpu attention

what is vectored interrupt system?

Assigning each interrupter device a unique code, typically four to eights bits (id)

mean memory - only storage media that cpu can access directly.
second storage - extension of main memory.
hard disk - glass patters covered with magnetic.
disk surface is logical divided into tracks, and tracks subdivided into sectors.

what is disk controller?

Determines the logical interaction between device and computer(cpu and main
memory)

what is solid state disks(ssd)?

It's faster than hard disk, nonvolatile

what is caching?

Copying information in faster storage system , main memory can viewed as cache
for secondary storage

what is device driver?

For each device controller to manga I/O

what is caching, ?

It's very important concept in computer , performed on all level and aspects
of computer like hardware and software, by taking a copy from information
to access this information second time faster, and don't access main memory,
or second memory again

what is multiprocessors used for?

• increased throughput(number of operation executed)
• economy of scale
• increased reliability

what type multiprocessing?

• asymmetric multiprocessing
• symmetric multiprocessing

what is multicore or multichip?

Is a term that describe a computer or processor that has than more than
one center unit (CPU)

what is clusterd system?

Like multiprocessing system but multiple system work together via
storage area network (SAN)

what is asymmetric clustering?

Has one machine in hot standby it's continuously Monintering the full system
while all nodes(processes) running

what is symmetric clustering?

Has multiple nodes running applications and monintering other nodes as well

some clusters are high performance computers(HPC)

what is distributed lock manager?

To avoid conflicting on system resource by listing all system resources and
provide locking mechanisms to control and allocation for modification for
system resources

Explain multiprogramming benefits?

• Organization jobs so cpu allows had execute
• one job selected and schedule via job scheduling
• when it's must wait for job cpu switch to another one
• single user cannot keep cpu busy all time

Explain timesharing benefits?

CPU switches jobs so frequently that users can interact with each job
while it is running, creating interactive computing

What is Dual Mode?

It's allow Os to protect itself and other computer components system

What is Timer to prevent infinite loop / process hogging resources

• Timer is set to interrupt the computer after some time period
• Keep a counter that is decremented by the physical clock.
• Operating system set the counter (privileged instruction)
• When counter zero generate an interrupt
• Set up before scheduling process to regain control or terminate
  program that exceeds allotted time

continue:./study_os_l2.md
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