Week 5 - Operating System Fundamental

Question 1

What is the role of human operator in early computing systems?

Answer 1

Keyed in programs by hand to control system functions,loaded tapes,fed in cards/paper tape, and maintained the system.

Question 2

Why was human input critical in early computers?

Answer 2

Few programs could read/write from a keyboard or disk; no monitiors or keyboard were available

Question 3

What is an operating systems?

Answer 3

• An operating system is a program or collection of programs that makes it easier for us to use a computer.

Question 4

What are the examples of an operating system?

Answer 4

1. DOS,OS/2, Window XP
2. FreeBSD,Fedora, Solaris,Mac OS
   3.iOS, Android, Symbian OS

Question 5

How does the operating system work from the user’s perspective?

Answer 5

It is designed for ease of use - it hides the hardware complexity:

1. Exciting user program
2. Convinent interface

Question 6

From a user’s perspective, what is less important regarding the Operating System?

Answer 6

Resource Utilisation does not appear to be important.

Question 7

What are the objectives of an operating systems?

Answer 7

• A program that controls the execution of application programs
• An interface between applications and hardware

Question 8

What is the main objectives of an OS?

Answer 8

• Convenience
• Efficiency
• Ability to evolve

Question 9

What are the components found in a computer system and explain its functions?

Answer 9

1. Hardware: basic computing resources
2. Operating system: controls and coordinates use of hardware amongst applications and users
3. Application Programs: Used to solve computing problems such as compilers, text editors, email clients etc.
4. Users: people, machines and other computers

Question 10

What is the role of an operating system?

Answer 10

• A computer is a set of resources for the movement, storage, and processing of data and for the control of these functions.
• The OS is responsible for managing these resources.

Question 11

What resources does an OS manage?

Answer 11

CPU time, memory space, file storage space, and I/O devices.

Question 12

What is the evolution of the OS?

Answer 12

1. Serial Processing
2. Simple Batch Systems
3. Multi programmed batch systems
4. Time sharing systems

Question 13

What were the problems associated with serial processing in the earliest computers?

Answer 13

1. Scheduling - Most installations used a hard copy sign-up sheet to reserve computer time. Time allocations could run short or long, meaning computer time is wasted.
2. Setup time - Considerable amount of time was spent just on setting up the program to run

Question 14

In the earliest computers, what was were the features?

Answer 14

1. There was no operating system, this means programmers interacted directly with the computer hardware
2. Users have access to the computer in “series.”
3. Computers ran from a console with display lights,toggle switches, som from of input devices, and a printer.

Question 15

What tasks did the perators perform?

Answer 15

Loaded magnetic tapes,fed in punched cards or paper tape, and kept the system running smoothly.

Question 17

What were some limitations of early computer systems?

Answer 17

Lack of screens and keyboards, manual program input, and limited automatic data input/output

Question 18

How did human operators manage early computer systems?

Answer 18

They worked in shifts, fed in cards or paper tape to maintain the system which was about 40 hours per week per shift.

Question 19

How did the number of operators change from 1967 to 1970?

Answer 19

In 1967, there was only one operator and by 1970, the system operated with four shifts

Question 20

What were the challenges of early computer operation?

Answer 20

The work was laborious, expensive, tedious and error-prone

Question 21

Why was operating early computer systems considered tedious and expensive?

Answer 21

It required constant manual input and long work hours, and it was highly prone to human error.

Question 22

What happened as institutions installed faster and more powerful computers?

Answer 22

The limiting factor was that the human operators couldn’t keep up with the new system speeds

Question 23

Why was there a need for an auto matic system in early computing?

Answer 23

To free operator from tedious and repetitive tasks.

Question 24

What major development emerged to address operator limitations?

Answer 24

The arrival of the Operating System

Question 25

What does an Operating System provide?

Answer 25

A simpler abstraction of the underlying hardware

Question 26

What is another role of an Operating system?

Answer 26

It acts as a resource manager, managing hardware and software resources

Question 27

What is an Operating System from a technical perspective?

Answer 27

A layer of system software that acts as an intermediary between the user and the computer's hardware.

Question 28

How is the OS viewed from the system's perspective?

Answer 28

It is closely involved with the hardware and acts as a resource manager and allocator

Question 29

How else can the OS be described?

Answer 29

As a control system between I/O devices and the user's programs.

Question 30

What is one important role of the OS in managing execution?

Answer 30

Preventing errors and improper use of the system.

Question 31

What is the basic definition of an OS?

Answer 31

A program that controls the execution of application programs and serves as an interface between applications and hardware.

Question 32

What role does the OS play between software and hardware?

Answer 32

It acts as an interface, managing communication between applications and hardware.

Question 33

What defines a modern computer system?

Answer 33

Connectivity- through networks and the internet, enabling data sharing and remote access

Question 34

How do modern computer systems handle multiple tasks?

Answer 34

Multitasking, multiprocessing and virtualisation technologies

Question 35

What services does OS provide for programs?

Answer 35

Program development and program execution.

Question 36

How does the OS manage hardware interaction?

Answer 36

By providing access to I/O devices and controlled access to files

Question 37

What system-level services does the OS offer?

Answer 37

System access and accounting for resource usage.

Question 38

How does an OS ensure system stability?

Answer 38

Through error detection and response

Question 39

What is an analogy for understanding the OS's control role?

Answer 39

Like a thermostat controlling a heating system, the OS manages the computer's resources externally.

Question 40

What was Serial Processing in early computers?

Answer 40

Users interacted directly with hardware,running one program at a time without an operating system

Question 41

What equipment did early computers use during Serial processing?

Answer 41

Consoles with display lights,toggle switches,input devices, and printers

Question 42

What were two major problems in Serial Processing?

Answer 42

Scheduling issues and long setup times

Question 43

How was computer time scheduled during Serial Processing?

Answer 43

Users signed up on hardcopy sheets, but time management was inefficient and led to wasted computer time.

Question 44

Why were simple Batch system developed?

Answer 44

- Early computers were very expensive -It is important to maximise processor utilisation to get full value from the machine

Question 45

What is a monitor in a Simple Batch System?

Answer 45

- A system program that manages the execution of jobs - Users no longer had direct access to the processor. - After a job finished, the program branches back automatically to the monitor

Question 46

How were jobs processed in a Simple Batch system?

Answer 46

- Users submitted jobs to a computer operator - Operator batched jobs together - Jobs were placed on an input device for the system to process in sequence.

Question 47

What is the main function of a monitor in a computer system?

Answer 47

It controls the sequence of events in the system, ensuring that jobs are managed and executed in the correct order.

Question 48

What is a resident monitor?

Answer 48

It is a type of software that always remains in memory, constantly ready to manager and control the execution of programs

Question 49

How does the Monitor interact with jobs?

Answer 49

It reads in a job, transfers control of the system to the job for execution, and then regains control when the job finishes.

Question 50

How does the processor interact with the Monitor in a computer system?

Answer 50

The processor executes instructions from the section of many of memory that contains the Monitor program, managing the control flow of the system.

Question 51

What happens when the processo is executing a user program?

Answer 51

Processor executes the instruction in the usr program until it encounters an ending conditon or an error condition

Question 52

What does it mean by "control is passed to a job"?

Answer 52

When control is passed to a job, it means the processor is fetching and executing instructions from the user program

Question 53

What does it mean when "control is returned to the monitor"?

Answer 53

When control is returned to the monitor, the processor stops executing the user program and resumes fetching and executing instructions from the monitor program.

Question 54

How does processor time behave in a simple batch system?

Answer 54

In the simple batch sytem, the processor alternates between executing user programs and executing instructions from the monitor.

Question 55

What are the sacrifices made when using a Monitor in a Simple Batch System?

Answer 55

Some of the main memory must be allocated to store the Monitor, and some of the processor time is consumed by executing the Monitor's instructions instead of user programs.

Question 56

Despite the overhead introduced by the Monitor, what is the overall effect on system performance?

Answer 56

Despite the memory and processor time overhead, the simple batch system significantly improves the overall utilization of the computer compared to earlier methods.

Question 57

What happens in a Uniprogramming system when an I/O instruction is encountered?

Answer 57

In a Uniprogramming system, the processor spends time executing instructions until it reaches an I/O instruction, after which it must wait for the I/O operation to complete before it can continue processing.

Question 58

What is a memory requirement for Multiprogramming?

Answer 58

In a Multiprogramming system, there must be enough memory to hold both the operating system (the resident monitor) and at least one user program at the same time.

Question 59

How does Multiprogramming improve processor utilisation?

Answer 59

When one job needs to wait for an I/O operation to complete, the processor can switch to execute another job that is ready and not waiting for I/O, thus keeping the processor busy.

Question 60

What is the purpose of a Time Sharing System?

Answer 60

A Time Sharing System is designed to handle multiple interactive jobs, allowing several users to interact with the computer at the same time.

Question 61

How is processor time managed in a Time Sharing System?

Answer 61

In a Time Sharing System, the processor time is shared among multiple users, with the system rapidly switching between users to give the impression of simultaneous access.

Question 62

How do multiple users interact with a Time Sharing System?

Answer 62

Multiple users simultaneously access the system through terminals, and the operating system interleaves the execution of each user program by giving it a short burst, or quantum, of processor time.