Operating system & different types of Software

Q1. a)  Give difference between  System software  and  Application software .

System software :

✬  A software designed to control computer hardware and provide platform for other application software to run on the computer.

✬  It allows application software to interact with computer hardware.

✬  It provides a human computer interface (HCI).

✬  It controls the allocation and usage of hardware resources.

✬  It is an independent software installed with Operating System.

Example : Operating System, Device driver, Utility software, Assembler, Compiler . . . etc.

Application software :

✬  A software designed to perform specific tasks as per user's request.

✬  It runs on the platform provided by the system software (can't run independently).

✬  It provides it's own user interface to interact with computer to perform tasks the software is designed to do.

✬  The user can execute the software as and when they require.

✬  It may be a single program (like, NotePad) or a suite of programs (like, Microsoft Office).

Example : Word processor, Spreadsheet, Database, Web browsers, . . . etc.

b)   What is   Operating System (OS)  ? Give few examples.

✬  Operating system is a set of system software that controls the hardware and helps other application software to run on the computer.

✬  A Computer system can not work without operating system because all other software like system and application software depends on operating system.

✬  It runs in the background, providing security to the system and files.

✬  It provides User Interface to interact with the computer.

Example : Windows, Android, Linux, Unix, MAC, iOS, . . . etc.

c)   What is   Utility software   ? State different types of utility software.

✬  Utility software is a system software designed to analyze, configure, optimize and maintain a computer resources like hardware, software and data storage.

✬  They are small programs generally included with Operating System or installed separately.

Example : File manager, File Compressor, Disk Scanner, Disk Defragmenter, Diagnostic Utility, Antivirus, Backup Utility, Data Recovery Utility . . . etc.

Q2. a)  Describe  Device driver  with its purpose.

⇒  Device driver is a system software that allows the operating system to communicate with a specific hardware device.

⇒  Drivers are hardware dependent and operating-system-specific.

⇒  It operates and controls a particular hardware attached to the computer, like Sound card, Graphic card, Network card, Printer ...etc.

b)  Explain the  function of a device driver. 

Device driver provides software interface for operating system to interact with computer hardware; allows to operate and control a specific hardware; translates data into a format understood by the hardware.

c)  What is meant by  descriptor  in a Device driver ?

⇒  All Device drivers contain a collection of basic information about the devices called Descriptor.

⇒  Descriptor includes unique manufacturer-ID, product-ID and serial numbers to identify the connected device.

⇒  The operating system uses these information to determine which device driver must be loaded to use that device.

d)  What is the  role of descriptor  when a new memory stick is plugged into a USB port of a computer for the first time ?

✬  The USB port provides power supply to the device, to activate and communicate with computer.

✬  The OS (operating system) sends a request to the USB port to identify the device.

✬  The unique manufacturer-id, serial number and type of the device stored in device descriptor is send to the OS.

✬  The operating system uses these numbers to determine which device driver must be loaded to use that device.

✬  The serial number is used to recognize the device, no matter which USB port it is plug into.

✬  Serial numbers are optional, If a device has no serial number associated with it, the operating system will treat the device as new every time it is plugged into a USB port.

✬  Serial numbers must be unique, If two different devices with same serial number were plugged into a computer at the same time, the device could not be identified and will not work.

Q3. a)  Describe what is meant by  Firmware  .

⇒  Firmware is a piece of software stored in the read-only memory chip of a device at the time of manufacturing in order to make the device run properly.

⇒  It provides low level control for devices.

⇒  It provides necessary instructions to the device for communicating with other computer hardware.

⇒  Firmware is read only and do not need to be changed.

b)  Give two examples of firmware used in computer devices.

1. Basic Input/Output System (BIOS), a firmware which initializes and controls the input and output operations.
2. Startup program called Bootstrap, a firmware which performs basic functions, identifies and loads OS.
3. Computer’s factory settings, a firmware that stores its default settings.

b)  What is the major difference between firmware and device driver?

✬  Firmware is the software that runs on the device.

✬  A device driver is the software that tells your operating system how to communicate, control and operate the device.

c)   Is it possible to replace or upgrade Firmware?

Most devices allows firmware updates from time to time, upgrading Firmware simply replaces the current version with latest new version.

But while running an update, if something goes wrong you can't just uninstall or replace it. The ROM, PROM and EPROM need the firmware to function.

Q4.  Describe what is meant by  Booting (or) Bootstrap loader. 

The process of switching ON the computer and loading the Operating System in the primary memory RAM is called Booting.

Q5. a)  Describe  Operating System  .

✬  Operating system is an essential software that must be installed on a computer to make use of it.

✬  Operating system is a set of programs that controls the hardware and helps other application software to run on the computer.

✬  It runs in the background of a computer system.

✬  It provides User-interface to interact with the computer.

✬  It provides security to the system and files.

Example :

Microsoft Windows, Apple Mac OS, Google Android, Apple iOS, Linux, Unix, MS-DOS ...etc.,

b)   Give six   basic functions   of operating system.

1. It provides User-interface to interact with the computer.
2. It allocates the CPU timing to do a task for each software.
3. Manages the memory used by software in RAM and save files in secondary storage.
4. Controls the peripheral devices like keyboard, mouse, monitor etc.
5. Allows application to save, delete, rename, edit files using File Manager.
6. Provides security to the system and files (access rights, user accounts, firewalls etc).
7. Provides Network Communication.

Q6. a)  Why Operating System is necessary for the Computers, but not for some other Microprocessor controlled devices ?

✬  Computer's fundamental goal is to run user's program, so a Operating system is essential to provide a platform for application programs to run and make use of its hardware resources.

✬  Microprocessor controlled devices are made to do only few specific tasks, which can be done by storing a firmware permanently in the device during manufacturing.

b)   Give few examples of microprocessor controlled devices that do not need an operating system.

1. Microprocessor controlled Alarm system.
2. Automatic Washing Machine.
3. Microwave oven.
4. Electronic Calculator.
5. Digital Watch.

Q7.  Give reason why operating system is loaded from hard disk rather than ROM.

⇒  It is easy and cheap to update Operating system if it is loaded in hard disk rather than ROM chip.

⇒  It can allow a user to choose any one from number of Operating system loaded in the hard disk.

Q8. a)  Give 4 ways Operating system  controls Hardware  of a computer.

1. It allocates the CPU time to do a task.
2. Controls the amount of memory used.
3. Controls the disk space used.
4. Controls the peripherals such as keyboard, mouse, printer etc.

b)  Give 4 ways Operating system  controls Software  of a computer.

1. Allows the other application software to save, copy, delete and rename files using ‘File management’ utility.
2. Allow more than one program to run at the same time called Multi-tasking.
3. Allow more than one user on a network to access the same files called Multi-user.
4. Provides security to the system and files (access rights, user accounts, firewalls, etc.).

Q9. a)  What is meant by  User Interface  or  Human Computer Interface (HCI). 

Human computer interface (HCI) is a communication system with hardware and software which allows the user to interact with the Computer using Cursor, Prompts, Icons, Menus etc. to get something done by the computer.

b)  Describe the following two types of User Interface.

Command-line Interface (CLI) :

⇒  The Interface which provides a way to type-in the Commands or Instructions on the screen to get something done by the computer.

Graphical User Interface (GUI) :

⇒  The Interface which provides Commands or Instructions in Graphical form to the user like, Icons, pull-down Menus, Windows and Pointer to select and interact with computer.

c)  State three  advantages for using GUI  (Graphical User Interface).

1. It is User-friendly / Easy to select.
2. It avoids Typing errors / No need to type command.
3. No need to remember commands.
4. Selecting item using mouse is faster than entering commands.
5. Allows Multitasking (several programs can be opened at the same time).

d)  In human-computer interaction, what computer term  WIMP  stands for?

WIMP is an acronym for Windows, Icons, Menus and Pointers, which denotes the style of interaction using these elements of the user interface.

WIMP best describes Graphical User Interface like, - Microsoft Windows for PCs, MacOs for Apple Macintosh, UNIX, etc.

Q10.  Explain the functions of each of the following features of the operating system.

a)   Memory management 

1. Keep track of the status of each memory locations free and allocated.
2. Checks that each process have enough memory allocated to them.
3. Manages the transfer of pages between Virtual memory and RAM.
4. Make sure that two process don't try to access the same memory location.

b)   Security management 

1. Its main function is to ensure the integrity, confidentiality and availability of data.
2. Prevent illegal intrusion and maintain access rights by providing user privileges, through User-ID and password to ensure the privacy of data.
3. Ensure that anti-virus software is always up to date.
4. Use firewall to check all incoming and outgoing traffic of the computer.
5. Update operating system whenever they become available.
6. It offers the ability to restore the system and recover data when it has been lost or corrupted.

c)   Management of user accounts 

1. Allows more than one user to log onto the computer system.
2. Each person is given a user account protected by a user name and password.
3. Each user's data is stored in separate parts of the memory to ensure data privacy.
4. It allows each user to customize their screen layout and other settings.
5. The user with administrator privilege can only create, delete and restrict user account.

d)   Hardware management 

1. Communicates with all Input and Output devices using device drivers.
2. Use a device driver to take data from a file and translates it into a format that the input/output device can understand.
3. Ensures each hardware resource has a priority so that they can be used and released as required.
4. Manages input/output devices by controlling queues and buffers.

e)   File management 

1. Allows application software to create, open, close, delete, rename, copy and move files.
2. It ensures the name of the file is appropriate according to the rules of naming files. (like, filename <= 255 characters and extension name <=4)
3. Maintain the directory structures to read and write files in HDD/SSD.
4. Provides file access control mechanisms like, access rights to files for editing and locking them using password protection.

f)   Multi-tasking 

1. Multitasking allows more than one program or process to run at a time.
2. Operating system (OS) allocates CPU timing for each process to do its task.
3. Each process shares the hardware resources, with effective use of CPU time, controlled by OS.
4. Each process is given a priority level, so it can have resources according to its priority.
5. Automatically interrupts the running program, saving its state and loading the saved state of another program and transferring control to it.

Q11. a)  Describe what is meant by  Virtual memory .

⇒  Virtual memory is a volatile physical memory RAM created temporarily on the secondary storage drive HDD/SSD.

⇒  It is created when a computer is running many processes at once and RAM is running low or out of space.

⇒  It is used to compensate the storage space of RAM, by transferring pages of data from RAM to secondary storage HDD/SSD.

⇒  It is a memory management technique of Operating System that creates an illusion of having a large physical memory RAM.

b)  Describe  Disk thrashing  and give reason why does it occur.

✬  Disk thrashing is a problem that may occur when virtual memory is being used.

✬  The swapping of data between RAM and Hard disk causes a very high rate of hard disk read/write head movement.

✬  If more time is spent on moving data in and out of memory, then the speed of processing data will be considerably reduced.

✬  It can also lead to premature failure of a hard disk drive.

Q12. a)  Describe what is meant by  Buffer  with example.

✬  Buffer is a temporary memory usually in RAM that holds data right before it is used.

✬  It is used to compensate the difference in processing speed of CPU and peripheral devices.

✬  It allows the processor to perform other tasks while waiting to receive or send data to input/output devices.

Example :

1. Buffer is used when streaming an audio or video file from the Internet. First around 20% of the file is downloaded and stored in the Buffer memory before it begins to play. This ensures that the video playback doesn't stop and wait for data from the internet. While the clip plays back, the computer continually downloads the rest of the clip and stores it in the buffer.
2. Print Buffer is used hold data before it is sent to the Printer. It allows the processor to perform other tasks while data is being printed.
3. Data Buffer is used to hold data before it is stored in Secondary storage device. It helps to compensate the difference in transmitting speed of processed data and Read/Write speed of Secondary storage.

b)  What does  Spooling  mean?

✬  Spooling is the process of putting multiple jobs in a buffer, a special area in memory or on a disk where a device can access them when it is ready.

✬  Spooling is a combination of buffering and queueing, useful because devices access data at different rates.

Example : Print Spooling enables you to send large document files or a series of different files in temporary memory before it is Printed.

Q13. a)  Describe what is meant by  Interrupt  with example.

✬  An Interrupt is a signal sent from a device or from software to the processor.

✬  It causes the processor to temporarily stop its current task and serves the interrupt.

✬  The purpose of interrupt is to get the attention of CPU.

✬  When an Interrupt is generated it is put in a queue called IRQ (Interrupt request Queue) according to its priority.

Example : Interrupts can occur when -

1. the user has pressed a key to interrupt the current process.
2. an error has occurred, such as a paper jam in a printer.
3. a software generate error message or if it crashes.

b)  Give two ways that  hardware   can cause an  interrupt  to occur.

1. Printer can cause an interrupt and produce error when a paper jam in a printer.
2. Key-board can cause an interrupt to halt the current process of CPU and execute command driven by keypress, like <Break>, <Pause>, <Esc>, . . . etc.
3. Moving the mouse trigger hardware interrupts that cause the processor to read the mouse position.

c)  Give two ways that  software   can cause an  interrupt  to occur.

1. Software interrupts are generated and stops the program with error message when something goes wrong or it crashes.
2. Software Interrupts are generated by programs when they want to request a system call to be performed by the operating system. A software interrupt only communicates with the Operating system (kernel) and indirectly interrupts the CPU.

d)  A printer sends an interrupt to the computer to say that it is out of paper.

Describe the stages involved in the processor handling the interrupt

✬  When the Interrupt signal is sent to CPU, microprocessor checks its priority index in the Interrupt Request Queue (IRQ).

✬  If the priority index of the interrupt received is higher than the current task, then CPU stops and stores the current process.

✬  Checks the source of the Interrupt and call the relevant Interrupt Service Routine (ISR) to serve the Interrupt request.

✬  After finishing the Interrupt request, CPU restores and continue with the stored process.

Q14.  Describe what is meant by  Interrupt Request Line (IRQL). 

✬  Interrupt Request Line is the Priority Index of an interrupt request from a device or software.

✬  IRQ lines are pre-assigned for particular devices when it is installed on the computer.

✬  All interrupts are not treated equally, CPU has to get its attention first to the device with priority index-1 usually the key-board.

✬  It serves the interrupts of a device or software according to its priority index that are pre-assigned in Interrupt request line (IRQ) for all peripheral devices.

Q15.  Describe  Polling  with example.

✬  Polling refers to the continuous checking the status of an external device by CPU or a client program.

✬  If it is ready, the computer will serve its request or send the data, and if not, the computer will return to a different task.

Example :  When a printer is connected via a parallel port, the computer continually interrogates the printer whether it is ready to receive the data or not.

Q16.  Describe  how buffers and interrupts are used  when a document is sent to a printer.

1. A portion of data from the document to be printed is sent to the printer buffer from the computer memory.
2. Processor continues with other job.
3. Printer buffer is emptied by sending the contents to the printer.
4. When print buffer is empty an Interrupt signal sent to processor requesting further data to be sent to buffer.
5. Processor stops its present job to refill buffer.
6. The process continues until the whole file is printed.

Q17.  Describe  how buffers and interrupts are used  when sending data to secondary memories such as Hard disk, DVDs or Solid state drive.

1. Microprocessor fills the buffer with data.
2. Processor continues with other job.
3. Buffer is emptied by sending the data to storage device.
4. When print buffer is empty an Interrupt signal sent to processor requesting further data to be sent to buffer.
5. Processor stops its present job to refill buffer.
6. The process continues until the whole file is written to the Hard disk, DVD or SSD.

Q18. a)  Describe what is meant by  BIOS  and state its function ?

⇒  BIOS stands for Basic Input-Output System.

⇒  BIOS program stored in special type of ROM chip called EEPROM, whereas BIOS settings are stored on a CMOS Chip (Complementary Metal Oxide Semi-conductor).

⇒  The microprocessor needs BIOS program to start up the computer system after it is powered ON.

⇒  BIOS acts as a mediator between microprocessor and Input-Output device.

⇒  It allows CPU to locate all necessary Input-Output devices and check if they all are properly functional.

⇒  It locates the Operating system and loads the key parts of OS in RAM memory from the Hard disk or SSD.

⇒  Operating system is required to provide a platform on which the application programs can run successfully.

b)  What is the task of BIOS when a computer is first powered up?

1. BIOS first determines whether all the necessary hardware and peripheral devices are in place and operational called Power-on Self- test (POST).
2. It locates the Operating system and loads the key parts of OS in RAM memory from the Hard disk or SSD.
3. It locates and loads the hardware device drivers that interface with the Operating system.
4. It allows to store the BIOS settings like system data/time and hardware settings in CMOS chip powered by a battery on the motherboard.

c)  BIOS software and BIOS settings are different.

Describe the different types of memory needs for both the software and its settings. In your explanation state why both types of memory are used.

⇒  BIOS is firmware stored in EEPROM and BIOS settings are stored on a CMOS chip.

⇒  EEPROM (Electrically Erasable Programmable ROM) is a special type of ROM; a flash memory chip, which retains data even when the computer is powered OFF. It means technically BIOS can be rewritten, updated or even deleted by the user.

⇒  CMOS (Complementary Metal Oxide Semi-conductor) is a chip that need power all the time to retain data, the power is provided by a battery on the motherboard. If battery is removed, then CMOS will lose all hardware settings and system configuration and will rest to default settings of BIOS.

⇒  BIOS program access BIOS setting to start up the computer system when it is powered ON. BIOS settings stores and maintains the system date/time, customized hardware settings and system configuration.