Chapter 1

Question 1

Resource Allocator

Answer 1

Allocates resources to specific programs and users so that it can operate the computer system efficiently and fairly.

Question 2

Control Program

Answer 2

Manages the execution of user programs to prevent errors and improper use of the computer, and it is specially concerned with the operation and control of I/O devices.

Question 3

Operating system

Answer 3

The program running at all times on the computer, usually called the Kernel.

Question 4

Kernel

Answer 4

The OS components running on the computer at all times after system boot.

Question 5

Two types of programs:

Answer 5

System programs and Application programs

Question 6

System programs

Answer 6

Are associated with the OS but are not necessarily part of the kernel

Question 7

Application programs

Answer 7

Include all programs not associated with the operation of the system.

Question 8

Middleware

Answer 8

Is a set of software frameworks that provide additional services to application developers.

Question 9

Device Driver

Answer 9

An operating system component that provides uniform access to various devices and manages I/O to those devices

Question 10

Bus

Answer 10

provides access between components and shared memory

Question 11

Device driver

Answer 11

understands the device controller and provides the rest of the operating system with a uniform interface to the device.

Question 12

What is used to ensure orderly access to the memory

Answer 12

a memory controller synchronizes access to the memory

Question 13

Interrupts

Answer 13

Alert the CPU to events that require attention.

Question 14

The controller informs the device driver that it has finished its operation via:

Answer 14

An interrupt

Question 15

Hardware may trigger an interrupt at any time by ending a signal to the:

Answer 15

CPU

Question 16

Table of pointers

Answer 16

They are used to provide the necessary speed to handle interrupts.

Question 17

Interrupt Vector

Answer 17

An OS data structure indexed by interrupt address and pointing to the interrupt handlers. a Kernel memory data structure that holds addresses of the interrupt service routings for the various devices.

Question 18

EEPROM

Answer 18

Electrically Erasable Programable Read-Only Memory.
- Low speed.
- contains mostly static programs and data that aren’t frequently used.

Question 19

The main difference among the various storage system lies in:

Answer 19

Speed, size (storage), and volatility.

Question 20

Storage device hierarchy

Answer 20

1) Registers (primary storage)
2) Cache (primary storage)
3) Main memory (primary storage)
4) Non-volatile memory (secondary storage)
5) HDDs (secondary storage)
6) Optical disk (tertiary storage)
7) Magnetic tapes ( tertiary storage)

Question 21

Mechanical Storage

Answer 21

HHDs, optical disks, holographic storage, magnetic tapes.

Question 22

Electrical Storage (NVM)

Answer 22

Flash memory, FRAM, NRAM, SSD.

Question 23

Direct Memory Access (DMA)

Answer 23

• Prevents overhead when transferring bulk data such as NVS I/O.
• Transfer an entire block of data from/to device to main memory.
• One interrupt is created, letting the CPU know that the transfer has completed.
• Prevents creating one interrupt for each byte of data.

Question 24

CPU

Answer 24

The hardware that executes instruntion

Question 25

Processor

Answer 25

A physical chip that contains one ore more CPUs

Question 26

Core

Answer 26

The core is the component that executes instructions and registers for storing data locally.

The basic computation unit of the CPU.

Question 27

Symmetric multiprocessing (SMP)

Answer 27

The most common multiprocessor systems use symmetric multiprocessing (SMP), in which each peer CPU processor performs all tasks, including operating-system functions and user processes.

Problem:
Since the CPUs are separate, one may be sitting idle while another is overloaded, resulting in inefficiencies.

Question 28

Non-uniform memory Access (NUMA)

Answer 28

The CPUs are connected by a shared system interconnect, so that all CPUs share one physical address space. This approach—known as non-uniform memory access, or NUMA.

Question 29

Timesharing (Multitasking)

Answer 29

It’s a logical extension in which CPU switches jobs so frequently that users can interact with each job while it is running, creating interactive computing.

• Response time < 1s
• CPU scheduling
• Clock interrupts at regular intervals

Advantages:
- Same as multi programming plus low response time
Disadvantages:
- same plus less efficient since spend a lot of time switching jobs

Question 30

CPU Scheduling

Answer 30

When several jobs are ready to run at the same time.

Question 31

Swapping

Answer 31

If processes don’t fit in memory, swapping moves them in and out to run.

Question 32

Virtual Memory

Answer 32

Allows execution of processes not completely in memory

Question 33

program vs process

Question 34

Program counter

Question 35

Dual-mode

Answer 35

Operation allows OS to protect itself and other system components

Question 36

Two Modes

Answer 36

User mode and kernel mode.

Question 37

Mode bit provided by hardware

Answer 37

Provides ability to distinguish when system is running user code or kernel code.

Some instructions are designated as privileged, only executable in kernel mode.

Question 38

Virtual machine manager (VMM)

Answer 38

In leasing CPU support with multi-mode operations.

Question 39

Timer

Answer 39

To prevent infinite loop / process hogging resources.
Interrupts the computer after some time period.
Keep a counter that is decremented by the physical clock
OS set the counter (privileged instruction)
When counter zero generate an interrupt

Question 40

The OS is responsible for the following activities in the connection with process management:

Answer 40

• Creating and deleting both user and system processes
• suspending and resuming processes
• providing mechanisms for
  
  • process synchronization
  • process communication
  • deadlock handling

Question 41

Deadlock

Answer 41

When two or more processes both need a resource that the other one has, and as a result it can’t make forward progress.

Question 42

Cache coherency

Answer 42

Multiprocessors environment must provide cache coherency in hardware such that all CPUs have the most recent value in their cache.

Question 43

Spooling

Answer 43

Process of saving up to the file until the output device is ready to accept it.