5.1 Operating Systems
AS Level · 13 questions found
What this topic covers
Section titled “What this topic covers”- Why a computer system needs an OS
- OS management tasks: memory, file, security, hardware (I/O), process management
- Utility software: disk formatter, virus checker, defragmenter, file compression, backup software
- Program libraries and DLL files: benefits to developers
Past paper questions
Section titled “Past paper questions”The Operating System (OS) is responsible for hardware and security management in a computer system.
(a) (i) State two tasks that are performed by hardware management. 2 marks
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(ii) State two tasks that are performed by security management. 2 marks
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(b) (i) Describe one benefit of using library routines when developing software. 2 marks
(ii) Describe one drawback of using library routines when developing software. 2 marks
(c) Identify two presentation features found in a typical Integrated Development Environment (IDE). 2 marks
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Show mark scheme
5(a)(i) [2 marks]
1 mark per bullet point, max 2 marks • Installs driver software for devices connected to external ports • Manages communication between devices • Manages hardware interrupts
5(a)(ii) [2 marks]
1 mark per bullet point, max 2 marks • Prevents unauthorised access • ... by providing authentication // by validating users and processes • Implements access rights and permissions • Makes provision for recovery of lost data • Carries out Operating System security updates as available • Carries out auditing and keeps logs of activity
5(b)(i) [2 marks]
One mark for benefit , one mark for appropriate matching expansion e.g. • Less code needs to be developed as code is pre-written • … thereby reducing the time to write a program • The library routine will be pre-tested and documented • ... reducing the time taken to test a program // giving confidence that the routine works as it should • The code for the library routine can written in a different programming language • … which allows the use of special features of that language • The user’s source code is more readable • ... as the library routine is simply called in the source code rather than being written out in full • The library could contain the code for complex routines • ... thus allowing the programmer to include modules they might not be able to code
5(b)(ii) [2 marks]
1 mark for drawback, 1 mark for appropriate matching expansion e.g. • Compatibility issues • … the library routine may not work with current program • Not guaranteed to be thoroughly tested • ... there could be unexpected problems (bugs/virus) • The library routine may not match needs exactly // The library routine may give unexpected results • … so it will need to be edited and tested • If the library routine is later edited or changed (by someone else) • … there could be unexpected errors or results
5(c) [2 marks]
1 mark per bullet point, max 2 marks • Prettyprint • Expanding and collapsing code blocks • Automatic / smart indentation / formatting
A restaurant accesses software and stores data using cloud computing.
(a) (i) Give two benefits of storing data using cloud computing. 2 marks
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(ii) Give two drawbacks of using cloud computing. 2 marks
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(b) The restaurant uses touchscreens as input devices to allow staff to select items from a menu.
(i) Explain how a touchscreen converts the point of touch to a selection from the menu. 4 marks
(ii) The image files that are displayed on the touchscreen have been corrupted. 2 marks
Identify two examples of utility software that could be used to recover the images.
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8(a)(i) [2 marks]
1 mark per bullet point, max 2 marks • Cloud storage can be free of charge for a limited amount • There is no need for personal storage devices • The data can be accessed from any computer with an internet connection • Cloud data services usually include data backup and recovery services • It is easier to share data / collaborate with colleagues • Cloud storage capacity can be quickly and easily increased if needed
8(a)(ii) [2 marks]
1 mark per bullet point, max 2 marks • The storage/cloud can only be accessed with an internet connection • There may be no backups // possibly no control over backups // reliance on third party for backups • Uploading / downloading data could take a long time • Potential issues with the cloud storage company impacting access e.g. downtime or technical problems • Potential compatibility issues if wanting to move the data • Limited storage availability without paying extra • … meaning (possibly) more expensive in the long term • Possibly security issues
8(b)(i) [4 marks]
1 mark per bullet point, max 4 marks Methods to determine point of touch ( Max 2) • Resistive // two layers of material make contact and complete a circuit • Capacitive // contact with the screen creates a change in charge • Infrared // the beams are broken by the pointing device • Optical imaging // a shadow is created when the surface is touched • Acoustic pulse // the acoustic wave is absorbed by the pointing device • Selection from the menu ( Max 2 ) • The point of touch is used to determine the x and y coordinates • The menu item corresponding to the coordinate position is recognised and the menu item is added to the order
8(b)(ii) [2 marks]
1 mark per bullet point, max 2 marks • Disk repair / disk contents analysis • Back-up software
A student uses a laptop to write a program that is saved as a text file.
(a) The laptop has utility software and an Operating System (OS).
(i) Describe the file management tasks carried out by an OS. 2 marks
(ii) Explain the need for back-up software. 2 marks
(b) The student compresses the file before it is emailed to their teacher as an attachment.
(i) Explain the benefits to the teacher of the attachment being a compressed file. 3 marks
(ii) Describe one lossless method of compressing a text file. 3 marks
(c) The student used a program library when writing their program. 3 marks
Explain the benefits to the student of using library files when writing a program.
(d) The program code is written using an Integrated Development Environment (IDE).
(i) One presentation feature found in a typical IDE is prettyprint. 2 marks
Identify and describe one other presentation feature found in a typical IDE.
Feature
Description
(ii) One debugging feature found in a typical IDE is single stepping. 2 marks
Identify and describe one other debugging feature found in a typical IDE.
Feature
Description
Show mark scheme
4(a)(i) [2 marks]
1 mark for each bullet point ( max 2 ) e.g. • Secondary storage space is divided into file allocation units • Space on secondary storage is allocated to particular files • Maintains/creates directory structures • Specifies the logical method of file storage e.g. FAT or NTFS • Provides file naming conventions • Controls user access // implements access rights //implements password protection // Makes file sharing possible • Controls access to the file by other software • Specifies tasks that can be performed on a file e.g. open, close, delete, copy, create, move, etc • Allows searching for a file
4(a)(ii) [2 marks]
1 mark for each bullet point ( max 2 ) • To allow data to be retrieved / restored when lost • To automatically make a duplicate copy of data… • …so the user does not have to remember to backup data • To make regular duplicate copies of data
4(b)(i) [3 marks]
1 mark for each bullet point ( max 3 ) e.g. • Less of the teacher’s storage space is used • ... so more student work can be stored • Transmission time is reduced • … so the teacher does not have to wait as long for it to arrive • Bandwidth usage is reduced • … so other transmissions are not adversely affected • Less data allowance is used on the teacher’s email system
4(b)(ii) [3 marks]
1 mark for each bullet point ( max 3 ) • Run-Length Encoding // RLE • Repeated sequences of the same characters are replaced by • ... a single copy of the character • ... and a count of the number of characters
4(c) [3 marks]
1 mark for each bullet point ( max 3 ) e.g. • It saves development time for the student • … by using pre-written code • There is less testing to do // the routines are more likely to work correctly • … because they have already been tested and are error-free • It results in a more robust program • Subroutines can be used that they do not have the skill to write • … which enables a more complex program to be written
4(d)(i) [2 marks]
1 mark for correct name, 1 mark for matching description • Expand/collapse code blocks… • … sections of source code that are part of the same block can be expanded to see the content or collapsed so that the overall code is seen • Auto-indentation // auto-formatting... • ... automatically indents/formats code as the user types so that the structure is clear // aids readability
4(d)(ii) [2 marks]
1 mark for correct name, 1 mark for matching description • Breakpoints … • … stops the code running on a set line to view the current status/variable contents/program flow • Report window // variable watch window … • … shows the values in variables/data structures and how they change when each line is run
A computer has an Operating System (OS).
Memory management and process management are two OS tasks.
Explain how memory management and process management support multi-tasking. 4 marks
Show mark scheme
6 [1 mark]
1 mark each to max 4 Max 3 marks for each management task: Memory management: Max 3 marks Stores data from all currently running programs concurrently in RAM Stops the data from overwriting each other in RAM/primary storage Decides which processes should be in main memory Makes efficient use of memory Process management: Max 3 marks Allows one process to be paused whilst another process can be actioned Decides which process is to be run next Switches between processes to allow them to share the use of the processor Identification/description of scheduling
A computer has an Operating System (OS).
(a) State one purpose of the Operating System. 1 mark
(b) The Operating System has utility software. 3 marks
The purpose of some utility software is to improve security.
Identify one example of utility software that is not intended to improve security.
Explain why this software is needed.
Utility software
Explanation
(c) An optical disc reader/writer is connected to the computer.
(i) Give the name of one port that can provide a connection for the optical disc reader/writer. 1 mark
(ii) Describe the roles of the address bus, the data bus and buffers in the process of writing data to the optical disc reader/writer. 3 marks
Show mark scheme
8(a) [1 mark]
1 mark for each bullet point ( max 1 ) • To hide the complexities of the hardware from the user • To provide a platform for software to run • To provide a user interface
8(b) [3 marks]
1 mark for the name of the utility software 2 marks for the explanation • Defragmentation software • … because over time saving and deleting of small files fragments the disk • ... the software makes (individual) files contiguous • … so access time to the files is improved • … because head movement is reduced • Disk contents analysis/disk repair software • … to identify and mark bad sectors • ... to restore corrupted files • ... to recover lost data (due to hardware failure) • File compression • … to reduce the size of files • ... which saves storage and memory space // by example • ... and reduces transmission time // by example • Disk formatter • … to prepare a disk for use // set up the file system • ... to partition the disc • ... to delete all the data from the disc
8(c)(i) [1 mark]
1 mark for each bullet point ( max 1 ) • USB / Universal Serial Bus • HDMI
8(c)(ii) [3 marks]
1 mark for each component ( max 3 ) Buffers • A buffer temporarily holds data until it is ready to be transmitted to the device Address Bus • The address of the data to be written to the device (in RAM) is carried on the address bus Data Bus • All data to be written to the device / buffer is carried on the data bus
A programmer uses an Integrated Development Environment (IDE) to develop a program that monitors air quality.
(a) Describe the following features of a typical IDE. 4 marks
Context‑sensitive prompts
Single stepping
(b) The program is distributed by downloading the source code and its library files from a web server.
(i) Explain the reasons for compressing the files. 2 marks
(ii) The program files are stored on a new hard disk after they have been downloaded. 3 marks
Describe the reasons why a hard disk formatter is needed for the new hard disk.
Show mark scheme
5(a) [4 marks]
1 mark for each bullet point ( max 2 for each feature). Context-sensitive prompts: • As the code is being written • …the options to complete the statement are shown Single stepping: • allows the programmer to execute the program one line at a time • …so that the effects of each statement can be seen
5(b)(i) [2 marks]
1 mark for each bullet point ( max 2 ). • To reduce the time it takes to download the program files from the web server // to upload them to the server in the first place • To reduce the amount of storage space used on the web server // user’s device
5(b)(ii) [3 marks]
1 mark for each bullet point ( max 3 ). • Disk needs to be prepared for initial use • Disk needs to be checked for errors • A new file system needs to be generated on the disk • The file allocation table needs to be set up
A computer has an Operating System (OS).
(a) Describe how the Operating System manages the peripheral hardware devices of the computer. 4 marks
(b) Hardware management is one key management task carried out by the Operating System. 2 marks
Identify two other key management tasks carried out by the Operating System.
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(c) The Operating System has utility software including defragmentation software. 3 marks
Explain how defragmentation can improve the performance of the computer.
(d) The computer stores data in binary form.
(i) State the difference between a kibibyte and a kilobyte. 1 mark
(ii) Convert the denary number 964 into Binary Coded Decimal (BCD). 1 mark
(iii) Convert the positive binary integer 11110010 into hexadecimal. 1 mark
(iv) Give the smallest and largest two’s complement binary number that can be represented using 8 bits. 2 marks
Smallest
Largest
(v) Add the following two binary integers using binary addition. Show your working. 2 marks
1 0 1 1 0 0 0 0 + 0 0 0 1 1 0 1 1
(vi) Show the result of a 3‑place right logical shift on the binary number: 1 mark
11001100
Show mark scheme
3(a) [4 marks]
1 mark each to max 4 Examples: Installs device drivers … to allow communication between peripherals and computer Sends data and receives data to and from peripherals … such as to an output device and from an input device/by example Handles buffers for transfer of data … to ensure smooth transfer between devices that transmit and receive at different speeds Manages interrupts / signals from the device
3(b) [2 marks]
1 mark each to max 2 Memory management File management Security management Process management Error checking and recovery
3(c) [1 mark]
1 mark each to max 3 Rearranges blocks of individual files (on the HDD) so they are contiguous // moves the free space together Accessing each file is faster …because there is no need to search for the next fragment / block of the file …so less head movement is needed
3(d)(i)
1 mark from Kibibyte is 1024 bytes and kilobyte is 1000 bytes Kibibyte is binary prefix and kilobyte is denary prefix
3(d)(ii) [1 mark]
1001 0110 0100
3(d)(iii) [1 mark]
F2
3(d)(iv) [2 marks]
Smallest: 10000000 Largest: 01111111
3(d)(v)
1 mark for working 1 mark for answer 1 0 1 1 0 0 0 0
- 0 0 0 1 1 0 1 1 1 1 0 0 1 0 1 1 1 1
3(d)(vi) [2 marks]
00011001
A student has purchased a new laptop.
(a) The laptop is designed using the Von Neumann model for a computer system. 2 marks
Identify two types of signal that a control bus can transfer.
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(b) Describe two ways the hardware of a laptop can be upgraded to improve the performance and explain how each upgrade improves the performance. 4 marks
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(c) Peripherals are connected to the laptop using ports.
(i) A printer is connected to a Universal Serial Bus (USB) port. 1 mark
Describe how data is transmitted through a USB port.
(ii) A monitor is connected to the laptop using a different type of port. 1 mark
Identify one other type of port that can be used to connect the monitor.
(d) The laptop has systems software.
(i) Describe how the Operating System (OS) manages processes in the computer. 5 marks
(ii) Describe the purpose of utility software in a computer. 2 marks
Show mark scheme
5(a) [2 marks]
1 mark each to max 2 Examples: Interrupt Timing Read Write
5(b) [4 marks]
1 mark for description; 1 mark for corresponding explanation Examples Increase number of cores Each core can independently carry out a process at the same time // so that more instructions are performed in parallel Increase RAM capacity ... allowing more applications to reside in memory at the same time, saving disk access times Increase cache memory More data can be stored in fast access so less time is spent accessing from RAM Increase clock speed More Fetch-Decode-Execute (FDE) cycles can run each second / per unit time
5(c)(i) [1 mark]
1 mark for a correct answer 1 bit is transferred at a time Can be synchronous or asynchronous earlier versions are half-duplex USB-3 is full duplex and
5(c)(ii) [1 mark]
1 mark for identification of a suitable port Examples HDMI DisplayPort
5(d)(i) [5 marks]
1 mark each to max 5 Manages the scheduling of processes // decides which order to run processes Manages which resources the processes require … such as allocating memory Enables processes to share data Prevents interference between processes // resolution of conflicts Handles the process queue It allows multi-tasking / multi-processing ... by ensuring fair access, handling priorities and handling interrupts
5(d)(ii) [2 marks]
1 mark each to max 2 To help users to set-up / configure / analyse / optimise / maintain the computer ... ... by for example, making memory allocation more efficient ... by for example, checking the system for faults
(a) State two benefits to a programmer of using Dynamic Link Library (DLL) files. 2 marks
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(b) Memory management is one of the tasks performed by an Operating System (OS). 2 marks
Describe the ways in which memory management organises and allocates Random Access Memory (RAM).
(c) An Operating System may include a utility program to compress text files. 3 marks
Describe one appropriate method of compressing a text file.
(d) Explain the reasons why increasing the amount of cache memory can improve the performance of a CPU. 2 marks
(e) State the name of a peripheral device port that provides a physical connection in the computer for each of these peripherals. 2 marks
3D printer
Monitor
Show mark scheme
7(a) [2 marks]
1 mark for each benefit ( max 2 ): • (main) memory requirements for program are reduced as dynamic link library is loaded only once / when required • the executable file size is smaller because the executable does not contain all the library routines • maintenance not needed to be done by the programmer because the DLL is separate from program • no need to recompile the main program when changes are made to DLL because changes / improvements/ error correction to the DLL file code are done independently of the main program
7(b) [2 marks]
1 mark for each bullet point ( max 2 ): • RAM is assigned into blocks • dynamic allocation of RAM to programs / processes • reclaims unused blocks of RAM • prevents two programs / processes occupying the same area of RAM at the same time • moves data from secondary storage when needed // manages paging, segmentation and virtual memory
7(c) [3 marks]
1 mark for each bullet point ( max 3 ): • lossless compression • Run Length Encoding • repeated sequences of characters are replaced by • ... a single copy of the character • ... and a counter of the number of characters
7(d) [2 marks]
1 mark for each bullet point ( max 2 ): • cache is fast access memory (close to the CPU) • cache stores frequently used instructions / data • ... more cache means more instructions / data can be transferred faster • ... less swapping between RAM and cache • prevents the CPU idling while waiting for data
7(e) [2 marks]
1 mark for each device. • 3D printer : USB port / COM port • Monitor : HDMI / VGA / USB / DisplayPort
A computer has system software including an operating system.
(a) Describe the key management tasks of an operating system. 4 marks
(b) Utility software is a type of system software.
(i) Describe the purpose of back-up software and defragmentation software. 4 marks
Back-up software
Defragmentation software
(ii) Give one other example of utility software. 1 mark
Show mark scheme
4(a) [4 marks]
1 mark for identifying task, max 2 for each description Max 2 for only identifying tasks without descriptions e.g. Memory management Controls the movement of data between RAM, processor, VM etc allocates memory to processes File management Creates files/folders Renames file/folders Security management Creates accounts/passwords Provide /upgrade firewall / anti-malware Hardware management Receives data from input devices ///sends data to output device Use of device drivers Process management Decides which process to run next supports multitasking
4(b)(i)
1 mark per point to max 2 for each Back-up To make a copy of data at regular intervals So that if it is lost/corrupted it can be retrieved Defragmentation Make individual files occupy contiguous blocks // move free space together Improve disk access times // Data/files can be loaded faster
4(b)(ii) [1 mark]
1 mark from e.g. Compression software (Hard) disk formatter Virus checker Disk analysis software Disk repair software
A computer has system software.
(a) The Operating System handles interrupts. 3 marks
| Tick () one box in each row to identify interrupt or a software interrupt. | whether each event is | s an example of a hardw |
|---|---|---|
| Event | Hardware interrupt | Software interrupt |
| Buffer full | ||
| Printer is out of paper | ||
| User has pressed a key on the keyboard | ||
| Division by zero | ||
| Power failure | ||
| Stack overflow |
(b) Describe the file management tasks that an Operating System performs. 4 marks
(c) Identify two utility programs that can be used to improve the performance of a computer and state how they improve the performance. 4 marks
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Show mark scheme
7(a) [3 marks]
1 mark per pair of rows (shaded & unshaded) Event Hardware Software Interrupt Interrupt Buffer full 1 Printer is out of paper User has pressed a key on the keyboard 1 Division by zero Power failure 1 Stack overflow
7(b) [4 marks]
1 mark for each bullet point to max 4 Storage space is divided into file allocation units • Space is allocated to particular files • Maintains / creates directory structures • Specifies the logical method of file storage (e.g. FAT or NTFS) • Provides file naming conventions • Controls access // implements access rights // implements password • protection // Makes file sharing possible Specifies tasks that can be performed on a file (e.g. open, close, delete, • copy, create, move etc.)
7(c) [4 marks]
1 mark for identifying program 1 mark for description, max 2 per program e.g. Defragmentation • Less time is taken to access files because each one is contiguous so • there is less head movement Virus checker • makes more RAM available for programs to run • ... because it removes software that might be taking up memory / • replicating Disk repair / Disk contents analysis • preventing bad sectors being used because it identifies / marks them • reduces access times by optimising storage • Disk/system clean up • releases storage by removing unwanted / temporary files •
Bingwen’s computer comes with an Operating System and utility software.
(a) Draw one line from each utility software to its correct description. 4 marks
Utility software Description
Scans software for errors and repairs the problems
Disk formatter
Defragmentation
Back-up
Disk repair
Moves parts of files so that each file is contiguous in memory
Creates a copy of data that is no longer required
Sets up a disk so it is ready to store files
Scans for errors in a disk and corrects them
Creates a copy of data in case the original is lost
(b) Identify four key management tasks that the Operating System will perform. 4 marks
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Show mark scheme
2(a) [4 marks]
1 mark for each correct line
2(b) [5 marks]
1 mark per bullet point to max 4 memory management • file management • security management • hardware / device / peripheral / resources management • input/output management • process management • error checking and recovery • provision of a platform for software • provision of a user interface •
Bingwen’s computer comes with an Operating System and utility software.
(a) Draw one line from each utility software to its correct description. 4 marks
Utility software Description
Scans software for errors and repairs the problems
Disk formatter
Defragmentation
Back-up
Disk repair
Moves parts of files so that each file is contiguous in memory
Creates a copy of data that is no longer required
Sets up a disk so it is ready to store files
Scans for errors in a disk and corrects them
Creates a copy of data in case the original is lost
(b) Identify four key management tasks that the Operating System will perform. 4 marks
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Show mark scheme
2(a) [4 marks]
1 mark for each correct line
2(b) [5 marks]
1 mark per bullet point to max 4 memory management • file management • security management • hardware / device / peripheral / resources management • input/output management • process management • error checking and recovery • provision of a platform for software • provision of a user interface •