Jigsaw — 5 System Software
Syllabus content for 9618 Topic 5, rebuilt bullet by bullet, with every tested angle mapped onto it.
Legend
Already examined in 9618
Tested in a 9618 paper (2021 onwards). Latest question ID given.
9608 only (not yet in 9618)
Tested under the old 9608 syllabus, still inside the 9618 syllabus wording.
Not yet tested — inference
In syllabus, not yet asked in either series (or only asked in a much narrower form). Justification given.
From the Save My Exams notes
Content the SME revision notes teach that no past question above covers.
The IDE bullet is new in 9618
The 9608 Legend has no questions at all under Describe features found in a typical IDE. Yet 9618 has examined it eleven times since 2021 — more than any other bullet in this chapter. It is 9618-only and heavily tested; treat 5.2.4 as a guaranteed topic, not an afterthought.
5.1 Operating Systems
5.1.1 Why a computer system requires an Operating System
Success
To provide a user interface … so that the user is able to communicate with the hardware · to manage memory … so that data can be stored and accessed, and multitasking is possible · to manage files … allowing the user to create, edit, update and delete files and folders · to manage inputs and outputs from hardware/peripherals · to handle processes … to make sure each process has fair access.
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Success
To hide the complexities of the hardware from the user · to provide a platform for software to run · to provide a user interface.
9618_w23_qp_12_sc_8.a
Warning
The hardware cannot be used without it // the computer would not function · it acts as an interface between the user and the hardware · it provides a platform on which application software can run.
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Warning
Given a description, name the software type: operating system, utility program, application software, compiler / translator. Tests the boundary between system software and application software.
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Types of user interface
“Provide a user interface” is credited in both questions, but no 9618 question asks what kind of interface — CLI, GUI, menu, natural language — or which suits which user. This is standard content elsewhere in the subject and sits directly under “why a computer requires an OS”.
What happens without an OS
Both questions ask for the OS’s purpose positively. The inverse — a machine with no OS would require every program to manage the hardware itself, with no multitasking, no file system and no common interface — has not been asked, in either series.
The interface types, with examples
CLI — text-based commands, used by advanced users (MS-DOS, Raspbian) · GUI — windows, icons, menus, pointers (WIMP), optimised for mouse and touch (Windows, Android, macOS) · Menu — successive menus with a single option at each stage (chip-and-PIN machines, vending machines, streaming services) · Natural language (NLI) — responds to spoken or textual input (Alexa, Siri, search engines). The one-line justification SME gives for the whole bullet is the cleanest available: a user does not need to know where on secondary storage data is kept, just that it is saved for when they want it again.
5.1.2 Key management tasks carried out by the Operating System
Success
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.
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Success
Manages the scheduling of processes // decides which process is to be run next · 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 · allows multi-tasking / multi-processing … by ensuring fair access, handling priorities and handling interrupts.
9618_s23_qp_12_sc_5.d.i;9618_w24_qp_12_sc_3.c
Success
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 // password protection // makes file sharing possible · specifies the tasks that can be performed on a file (open, close, delete, copy, create, move) · allows searching for a file.
9618_w21_qp_12_sc_7.b;9618_w24_qp_11_sc_4.a.i
Success
Installs device drivers … to allow communication between peripherals and computer · sends data to and receives data from peripherals … such as to an output device and from an input device · 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.
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Success
Installs driver software for devices connected to external ports · manages communication between devices · manages hardware interrupts.
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Success
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 OS security updates as available · carries out auditing and keeps logs of activity.
9618_w25_qp_11_sc_5.a.ii
Success
RAM is assigned into blocks · dynamic allocation of RAM to programs / processes · reclaims unused blocks of RAM · prevents two programs occupying the same area of RAM at the same time · moves data from secondary storage when needed // manages paging, segmentation and virtual memory.
9618_w22_qp_11_sc_7.b
Success
Memory management (max 3): stores data from all currently running programs concurrently in RAM · stops the data from overwriting each other in RAM · decides which processes should be in main memory · makes efficient use of memory. Process management (max 3): allows one process to be paused whilst another is actioned · decides which process is to be run next · switches between processes to let them share the processor · identification/description of scheduling.
9618_s24_qp_12_sc_6
Success
Hardware management → installs programs for devices connected to external ports · security management → validates user and process authenticity · memory management → dynamically allocates memory to processes · process management → allows processes to transfer data to and from each other. (Distractor: marks unallocated file storage for availability = file management.)
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Warning
Max 4 for each task. Process management — scheduling / decides which process runs next · allocates resources to processes · handles interrupts · prevents processes interfering with each other · enables multi-tasking by giving each process a share of processor time. User interface — allows the user to communicate with the computer · hides the complexity of the hardware · allows the user to run software, and to manage files and folders.
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State three tasks carried out by memory management [3]
Allocates memory to programs and data · keeps track of which memory is in use and which is free · deallocates memory when a process finishes · protects one program’s memory from another · allocates virtual memory, using paging or segmentation · moves data between main memory and backing store.
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State two tasks carried out by input/output device management [2]
Sends data to and receives data from peripherals · manages device drivers · manages buffers and queues for devices · handles interrupts raised by devices · detects devices as they are connected · keeps track of the status of each device · handles power management for devices.
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State three tasks carried out by error detection and recovery [3]
Deals with interrupts · deals with run-time errors · deals with hardware faults · produces error diagnostic messages for the user · deadlock detection and recovery · allows safe-mode boot-up · performs a controlled system shutdown · maintains and uses restore points.
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Warning
Match task to description across memory, file, device, security and interrupt processing.
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State three tasks carried out by file management [3]
Creates, opens, reads, writes, closes and deletes files · organises files into folders/directories · maintains the file directory structure and keeps track of where each file is stored · manages access rights to files · moves, copies and renames files.
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Warning
Max 2 marks per task. The 9608 format asks the candidate to select the tasks — so any two of memory, file, device, process, security must be describable to two marks each, not just nameable.
9608_w16_qp_12_sc_7
Warning
An 8-mark sequencing question: the application requests the file · the OS file management looks up the file in the directory · it finds the physical address (surface/track/sector) · device management issues the read to the disk controller via the device driver · the disk head is moved to the track, the sector is read into a buffer · an interrupt signals the transfer is complete · memory management allocates main memory for the data · the data is copied from the buffer into that memory and control returns to the application. The longest single question in the chapter in either series.
9608_w16_qp_12_sc_3
Paging, segmentation and virtual memory
Credited once, as an alternative mark point in
w22_qp_11_sc_7.b. Virtual memory also appears in the Chapter 4 RAM-performance mark scheme. But no question in either series asks what virtual memory is or how paging works — and virtual memory is the mechanism that connects memory management to system performance.
Error checking and recovery
Listed as a creditable answer in
s21_qp_11_sc_2.bands23_qp_11_sc_3.b, but never described. It is the only named management task with no descriptive question against it.
Scheduling described rather than named
“Manages the scheduling of processes” is a mark point in three separate questions; “identification/description of scheduling” is explicitly creditable in
s24_qp_12_sc_6. Yet no question asks how scheduling works — time slices, priorities, the ready queue. Given the tariff on process management questions (4–5 marks), this is the natural place for a harder question.
The five key tasks, as SME frames them
Memory management — allocating main memory (RAM) between programs open at the same time; copying programs and data from secondary to primary storage as needed. File management · Security management · Hardware management · Process management — as in the mark schemes above. Note the 9618 mark schemes also credit input/output management, error checking and recovery, provision of a platform for software and provision of a user interface as “key management tasks”, so the list is longer than SME’s five.
5.1.3 The need for typical utility software
Success
Virus checker → to scan for malicious program code · disk formatter → to initialise a disk · backup → to create copies of files in case the original is lost · disk repair → to check for and fix inconsistencies on a disk · defragmentation → to reorganise files so they are contiguous. (Distractor: to decrease the file size = file compression.)
9618_w22_qp_12_sc_1.a
Success
Defragmentation — over time saving and deleting small files fragments the disk; the software makes individual files contiguous; so access time is improved, because head movement is reduced. Disk contents analysis / disk repair — to identify and mark bad sectors; to restore corrupted files; to recover lost data. File compression — to reduce the size of files; saving storage and memory space; reducing transmission time. Disk formatter — to prepare a disk for use // set up the file system; to partition the disc; to delete all data from the disc.
9618_w23_qp_12_sc_8.b
Success
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 of the file · so less head movement is needed.
9618_s23_qp_11_sc_3.c
Success
The disk needs to be prepared for initial use · the 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.
9618_w23_qp_13_sc_5.b.ii
Success
Defragmentation — less time taken to access files because each one is contiguous, so less head movement · Virus checker — makes more RAM available for programs to run, because it removes software that might be taking up memory or replicating · Disk repair / disk contents analysis — prevents bad sectors being used because it identifies and marks them; reduces access times by optimising storage · Disk / system clean up — releases storage by removing unwanted or temporary files.
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Success
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 back up · to make regular duplicate copies of data.
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Success
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.
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Success
Disk repair / disk contents analysis · back-up software.
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Warning
Two marks per program: one for naming it, one for what it does. Disk defragmenter · back-up · virus checker / anti-malware · disk formatter · disk repair · file compression · system clean-up · firewall · encryption.
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Warning
The distractors matter: a translator, an IDE, graphics software and a spreadsheet are not utility programs.
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Warning
Back-up — a second copy exists if data is lost, corrupted or the hardware fails, so it can be restored. Defragmenter — files stored in scattered blocks are rearranged into contiguous blocks, so read/access time falls. Disk repair — scans the disk for bad sectors and corrupted files, marks bad sectors unusable and recovers what it can.
9608_s21_qp_12_sc_7.a.i–iii
Warning
The formatter organises the disk into tracks and sectors and builds the file system · the contents-analysis software scans the disk to identify used, free, bad and corrupted areas · the repair software then fixes or marks those areas so the disk remains usable.
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Warning
Checks the disk for errors and bad sectors · attempts to recover data from damaged areas · marks bad sectors so they are not used again · repairs the file system / directory so files can be found.
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Warning
Max 3 for each. Virus checker — scans files and memory for known virus signatures and for suspicious behaviour (heuristics) · quarantines or deletes infected files · must be kept up to date · can scan on demand or in real time. Back-up — makes a copy of files, on a schedule or on demand, to a separate medium or the cloud, so data can be restored after loss, corruption or hardware failure.
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Warning
Continuously in the background / in real time as files are opened or downloaded · on a scheduled full scan · whenever new external media is connected · immediately after the definitions are updated.
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Warning
Automatic, scheduled back-ups so a recent copy always exists · the back-up is kept on a separate device or off-site, so a local failure does not destroy it · restore points allow the system to be rolled back.
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File compression in its own right
Named in the syllabus notes and credited as one option inside
w23_qp_12_sc_8.b, but never the subject of its own question in 9618 — unlike defragmentation (three questions), disk formatter (two) and backup (two). Lossless vs lossy is Chapter 1 content, so a Chapter 5 question would be about why a utility for it is provided: saves storage, reduces transmission time, allows more files in the same space.
Virus checker described as a utility
Virus checkers are examined thoroughly in Chapter 6 as a security measure, and appear in Chapter 5 only as one line of a matching exercise and one mark point about freeing RAM. A question asking how a virus checker works as a utility provided with the OS would sit in both chapters.
Why defragmentation does not help an SSD
Every defragmentation mark scheme talks about head movement — which only exists on a magnetic hard disk. That defragmentation is pointless (and harmful) on solid state storage is never asked, despite Chapter 3 examining SSDs repeatedly.
Disk formatter, in full
Prepares a storage device for use by creating a file system and organising the space into sectors and tracks. Needed to wipe and re-initialise a disk before use, to change the file system format (e.g. FAT32, NTFS), and to remove all data and errors before installing a new OS or reusing a drive.
Virus checker — two detection approaches
Use a list of known malware signatures to block immediately, or monitor the behaviour of programs for suspicious activity — rapid deletion or modification of files, attempts to access sensitive data, communication with known malicious servers. Virus checkers also check for updates to the signature database. The behavioural-detection method is absent from every mark scheme in both chapters and is the more modern answer.
Why fragmentation happens
As programs and data are added to a new hard disk they are stored in order; over time, deleting files leaves gaps, and new data fills those gaps, so files end up split. Defragmentation can only be used on magnetic storage — the content for the
!infogap above.
5.1.4 Program libraries
Success
A set of pre-written / pre-compiled / pre-tested subroutines · which can be called in other programs · by installing / importing the library.
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Success
Programming time is saved as code does not have to be written from scratch · testing time is saved as code is already tested / documented · a library routine is more likely to work, as the code is already tested · library routines automatically update if they are changed or improved · the programmer can use library routines to perform complex functions they may not be able to write themselves.
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Success
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 testing time // giving confidence that the routine works · the code can be 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 routine is simply called rather than written out in full · the library could contain complex routines … allowing the programmer to include modules they might not be able to code.
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Describe one drawback of using library routines, with expansion [2]
Compatibility issues … the library routine may not work with the current program · not guaranteed to be thoroughly tested … there could be unexpected problems (bugs / virus) · the routine may not match needs exactly // may give unexpected results … so it will need to be edited and tested · if the routine is later edited or changed by someone else … there could be unexpected errors or results.
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Describe the benefits of creating a program library [3]
Subroutines can be shared / reused … between team members working independently … without having to rewrite or re-test them, saving the programmers’ time · a program library provides continuity between programs and programmers · individual programmers can contribute their specialisms to the library, or use the specialisms of others.
9618_w24_qp_12_sc_4.b
Explain two benefits of creating a Dynamic Link Library (DLL) [4]
Memory requirements are reduced … as the DLL is loaded only once / only when required · the executable file size is smaller … because the executable does not contain all the library routines · maintenance is not needed by the programmer … because the DLL is separate from the program · no need to recompile the main program when changes are made to the DLL … because changes, improvements and error corrections to the DLL are done independently of the main program · a single DLL can be made available to several application programs … saving memory.
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Success
Program libraries store pre-written functions and routines · the library can be referenced / imported · the functions/routines can then be called in her own program.
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Warning
The routines are already written and tested, so development is faster · they are reliable / error-free because they have been used many times · the programmer does not need specialist knowledge of that area · they can be reused in many programs · they may be optimised and so run efficiently.
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Warning
The DLL is only loaded into memory when it is needed, so memory use is lower · the executable is smaller · the DLL can be shared by several programs at once · the DLL can be updated or replaced without recompiling the main program.
9608_s20_qp_13_sc_4.a.i;9608_w16_qp_12_sc_8.b.i
State two reasons why a program might not use DLL files [2]
The program will not work if the DLL is corrupted · an external change to the DLL (by another program or a user) could stop the program working · the DLL must be present at run time — the executable is not self-contained (“unable to find X.dll”) · a malicious change to a DLL could introduce a virus.
9608_s20_qp_13_sc_4.a.ii;9608_w16_qp_12_sc_8.b.ii
Warning
Library routine — a pre-written, pre-tested block of code that performs a common task, stored in a library and called by a program. DLL — a file of one or more routines that is not included in the executable at compile time but is linked and loaded at run time, and can be shared between programs.
9608_s19_qp_11_sc_3.a.ii;9608_w18_qp_12_sc_6.b.i;9608_w16_qp_13_sc_2.c
Warning
Two marks each — point plus expansion. Benefit — already written and tested … so development time is cut and fewer errors are introduced. Drawback — the programmer cannot see or change the source code … so the routine may do more than is needed, be inefficient, or not fit the problem exactly.
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Drawbacks of a DLL
The benefits of DLLs have been examined three times (2, 4 and 4 marks). The drawbacks — version conflicts if a newer DLL is incompatible, the program failing to run if a required DLL is missing, security risk from a malicious or altered DLL, and errors being harder to trace across programs — have never been asked, even though
w25_qp_11_sc_5.b.iishows the examiners are willing to ask for library drawbacks.
Static linking versus dynamic linking
Every DLL mark scheme contrasts the DLL with “a library that does not include DLL files”, but the term static library is never used and the contrast is never asked for directly: a static library is compiled into the executable, making it larger but self-contained; a DLL is linked at run time.
Extra library advantages
Promotes code reuse — well-tested routines used in multiple programs, reducing duplication · improves reliability — routines are thoroughly tested and debugged · easier maintenance — updates to a routine benefit all programs that use it, especially with DLLs · efficient memory usage — DLLs are loaded only when needed at run time · standardisation — promotes consistency in how common tasks such as file handling and sorting are implemented. Typical library tasks: sorting, displaying graphics, playing sounds, managing data.
DLL drawbacks — the content for the untested bullet
Version conflicts if a newer DLL is not compatible · the program may fail to run if a required DLL is missing · security risk — a malicious or altered DLL can be substituted · debugging is harder — errors inside a DLL can be difficult to trace across the multiple programs that use it.
5.2 Language Translators
5.2.1 The need for an assembler, a compiler and an interpreter
Success
Compilers are used when a high-level program is complete; they translate all the code at once and produce executable / .exe / object code files that run without the source code. Interpreters translate one line at a time and then run that line, most useful while developing because errors can be corrected and the program continues from that line. Assemblers translate assembly code into binary / machine code.
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Success
A compiler checks all the code before attempting to translate; if any errors are found they are all reported at the same time and the program does not translate or run. If there are no errors the compiler produces an executable file / .exe which can run without access to the source / program code. An interpreter translates one line and runs it before moving on; if the line has an error the interpreter stops and displays the error; the programmer can correct the error immediately / in real time and the interpreter continues translating from that point.
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Success
Interpreter: use it while writing/coding the program … to test/debug the partially completed program … because errors can be corrected and processing continues from where execution stopped // errors are identified one at a time. Compiler: use it after the program is complete … to create an executable file so the source code is not seen … use it to repeatedly test the same completed section without having to re-interpret every time. (Max 2 each.)
9618_w25_qp_12_sc_10.a;9618_s21_qp_12_sc_7.b.i(max 3 each)
Warning
A four-row tick table across assembler, compiler and interpreter.
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Warning
Purpose — to convert program code written in one language (usually source code in a high-level or assembly language) into another form, usually machine code, so the processor can execute it. Other translators — assembler, compiler, interpreter.
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The assembler in its own right
Assembler is named in the syllabus bullet alongside compiler and interpreter, but appears in 9618 only as one gap in one cloze (
w21_qp_11_sc_4.d). Every other question in this bullet is compiler-vs-interpreter. “Explain the need for assembler software” — one mnemonic instruction maps to one machine code instruction, so a simple translator suffices, and assembly cannot be executed directly — has never been asked.
Why a high-level language needs translating at all
Implied throughout but never asked: the processor can only execute machine code, and a high-level statement corresponds to many machine code instructions.
The three translators compared
Assembler — translates mnemonics in assembly (low-level) into machine code; each line of assembly assembles into a single machine code instruction. Advantages: speed of execution; optimises the code; original source code will not be seen. Disadvantages: difficult to write due to limited, hard-to-understand commands; changes mean it must be reassembled; designed solely for one specific processor. Compiler — translates a high-level language into machine code all in one go, producing a distributable executable. Advantages: speed of execution; optimises the code; source code not seen. Disadvantages: can be memory intensive; difficult to debug; changes mean recompiling; designed for one specific processor. Interpreter — translates and executes one line at a time, stopping at the first error; does not generate machine code directly, but calls the appropriate machine code subroutines. Advantages: stops at a specific syntax error; easier to debug; requires less RAM. Disadvantages: slower execution; must be translated every time it is run; no optimisation. The “calls machine code subroutines rather than generating machine code” point and the RAM point appear in no mark scheme.
5.2.2 Benefits and drawbacks of a compiler or interpreter, and justifying each
Success
Easier to debug the program · because it translates line-by-line and stops when an error is found, whereas the compiler translates the whole program at once · only reporting one error at a time · which allows the error to be corrected in real time, whereas with a compiler the program must be corrected and recompiled · the program can restart at the same point where the error occurred, whereas with a compiler it must be re-run · the effect of any changes can be seen immediately · a partially completed program can be translated and tested on its own, which a compiler cannot do.
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Success
Large amounts of source code take time to compile · it can be slower to produce the object code than an interpreter · the code must be recompiled when it is changed · the program cannot run if there are errors · it is not possible to correct errors in real time · one error can cause false reporting of multiple further errors · sections of code / unfinished code cannot easily be tested.
9618_w25_qp_13_sc_8.a;9618_w22_qp_12_sc_1.b.i
Success
The program can be distributed without the source code … so it cannot be edited, stolen or plagiarised · users do not require the translator to run the program … so time is not spent retranslating by the user.
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Success
The compiler produces an executable file … so the user cannot access, edit or sell the code … and users do not need the translator to run the game · the game can be compiled for different hardware specifications … and then used to generate more income for the programmer · the program can be tested multiple times without having to retranslate each time.
9618_s23_qp_13_sc_5.a.ii
Success
The interpreter stops when an error is found … so the error can be corrected in real time, and the result of changes is seen immediately · only one error is displayed at a time … so there are fewer errors to correct simultaneously and no dependent errors.
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Success
Creates an executable file … so the code can be tested multiple times without having to recompile … so repeated testing takes less time.
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Success
No mark for the choice — all marks are in the justification. Interpreter: allows real-time changes … so the program can be debugged at each stage … the effect of changes is seen immediately · the developer can test when incomplete … so small parts can be tested without testing the rest … if one section does not work others can still be tested · to avoid dependent errors. Compiler: the developer can debug multiple errors simultaneously · produces an executable file … so the program can be tested multiple times without recompiling.
9618_s23_qp_12_sc_7.b
Success
The programmer can test sections of the code without every part working or being written · can debug in real time … so errors can be fixed and the program continued from that point · the effect of any changes can be seen immediately · to avoid dependent errors.
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Warning
Max 3 for each side. Interpreter — used while developing, because it stops at the first error and reports it with its line, errors are easier to find and correct, and no full recompilation is needed after every change. Compiler — used once the program is complete, to produce an executable that runs faster, runs without the translator present, can be distributed without the source code, and can be cross-compiled for a different platform.
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Warning
Errors are reported one at a time, as they are met, with the line number · the program can be run and tested without waiting for a full compilation · partially written programs can be run · it is easier to trace and debug · the same source can run on any machine with that interpreter.
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Warning
The source code is needed every time the program runs · no executable file is produced · the translator must be present on the machine · execution is slower, because each line is translated every time it is met (including on every loop pass).
9608_w21_qp_11_sc_10.b
Warning
The whole program must be compiled before it can be run · errors are reported only at the end, as a list, so debugging is slower · the source must be recompiled after every change · the object code is machine/platform specific · compilation of a large program takes a long time and uses memory.
9608_s21_qp_13_sc_7.a
Warning
A five-row comparison table — the densest single translator question in either series.
9608_w15_qp_13_sc_11
Warning
The code is sent as source to the client and must run on any browser / platform, so it cannot be pre-compiled to one machine code · it is interpreted by the browser as the page loads, so it runs immediately without a separate build step.
9608_w19_qp_11_sc_2.d
Advantages of a compiler asked positively
Nine questions in this bullet, and every one is either “advantages of the interpreter”, “disadvantages of the compiler”, or “why use a compiler at the end”. A plain “state two advantages of using a compiler” — faster execution of the finished program, optimised code, no translator needed at run time, source code protected — has not been set, even though all those points are credited elsewhere.
Disadvantages of an interpreter
Likewise untested as a question in its own right: slower execution because translation happens every run, the translator must be present on the user’s machine, the source code is exposed, and no optimisation is performed.
Execution speed of the finished program
Every 9618 question is about the development stage. The runtime difference — compiled code runs faster because it is already machine code, whereas interpreted code is retranslated line by line every time it runs — is the single most important compiler advantage and appears in no 9618 mark scheme in this bullet.
5.2.3 Programs partially compiled and partially interpreted
Success
Partially compiled programs can be used on different platforms, as they are interpreted when run · code is optimised for the CPU, as machine code is generated at run time · source code does not need recompiling, so it is more efficient to run.
9618_w23_qp_11_sc_6.b;9618_w22_qp_12_sc_1.b.ii
Warning
It has already been translated into machine code / an executable · so the processor can run it directly, and no translator is required on the customer’s computer (which also keeps the source code hidden).
9608_s20_qp_11_sc_8.b
The mechanism, not just the reason
Both 9618 questions ask why. Neither asks how: the source is compiled to an intermediate bytecode, which is then interpreted by a virtual machine on each platform. The syllabus names Java (console mode) explicitly, and the words bytecode and virtual machine appear in no 9618 mark scheme for this bullet — the nearest is “machine code is generated at run time”.
Java named in a question
The syllabus notes say “such as Java (console mode)“. Neither 9618 question names a language; both are generic. A question set in a named language context has not appeared.
Drawbacks of the hybrid approach
Untested: slower than fully compiled code because the intermediate code is still interpreted, and the target machine must have the virtual machine installed.
5.2.4 Features found in a typical Integrated Development Environment (IDE)
No 9608 questions, eleven 9618 questions
The most heavily examined bullet in this chapter, and entirely new in 9618. The syllabus notes group the features under four headings — coding, initial error detection, presentation, debugging — and 9618 questions almost always ask by heading, so learn them grouped, not as one list.
Success
For coding — Context-sensitive prompts: gives suggestions for code as the user types instead of having to write or remember the code. For coding — Auto-correct: corrects spelling mistakes so the user has fewer errors to correct. For presentation — Pretty-printing: colour codes keywords so the user can identify any errors. For presentation — Expand/collapse code blocks: the user can hide code they are not currently working on. For debugging — Single stepping: run the code one line at a time // shows the effect of each line of code. For debugging — Breakpoints: stop the code running at a set point to check the flow or variable contents. (1 mark feature + 1 mark matching description, ×3.)
9618_s24_qp_12_sc_8.b
Success
Single stepping — run the program one line at a time … and check the variable contents / program flow // show the effect of each line of code · Set breakpoints — run the code up to a set line … and then check the status · Variable / report watch window — view how the data changes as the program is running.
9618_w24_qp_12_sc_4.a
Success
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. (Max 2 per feature.)
9618_w23_qp_13_sc_5.a
Success
Breakpoints — stop the code at a specific line to check the current progress / values · Dynamic syntax checks — highlight / underline / colour syntax errors as the code is entered · Context-sensitive prompts — suggest the code to add // automatically complete statements · Single stepping — run the code one line at a time so the values can be checked.
9618_s23_qp_12_sc_7.c
Identify and describe one other presentation feature [2]
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 the overall code is seen · Auto-indentation / auto-formatting … automatically indents or formats code as the user types so the structure is clear // aids readability.
9618_w24_qp_11_sc_4.d.i
Identify and describe one other debugging feature [2]
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 and data structures and how they change when each line is run.
9618_w24_qp_11_sc_4.d.ii
Success
Prettyprint · expand/collapse code blocks · auto indentation / formatting.
9618_w25_qp_11_sc_5.c;9618_w23_qp_11_sc_6.c.i
Success
Single stepping · breakpoints · report window · variable expressions.
9618_w23_qp_11_sc_6.c.ii;9618_s21_qp_12_sc_7.b.ii
Identify three tools that support the writing of a program [3]
Colour coding // pretty printing · auto-complete · auto-correct · context-sensitive prompts · expand and collapse code blocks.
9618_w21_qp_11_sc_4.b.ii
Dynamic syntax checks as their own question
The syllabus notes give “initial error detection, including dynamic syntax checks” its own heading, alongside coding, presentation and debugging. It has appeared once, as one row of the
s23_qp_12_sc_7.ctable — whereas presentation and debugging have four questions each. It is the least-examined of the four headings and the most likely next target.
The IDE's built-in translators as a feature
s24_qp_12_sc_8.bexplicitly says “do not give translator as one of your features”, which tells you examiners consider it an obvious answer. Two other questions (s21_qp_12_sc_7.b.i,s24_qp_12_sc_8.a) treat the built-in compiler and interpreter as IDE features. The link — that an IDE bundles editor, translators and debugger in one environment — is never asked directly.
Why an IDE is used at all
Every question names features. “Explain the benefits to a programmer of using an IDE rather than a plain text editor” — errors caught as you type, no switching between tools, debugging without extra software, faster and more accurate coding — has not been set.
The four headings, with every feature the notes name
For coding: context-sensitive prompts (suggests completions as you type); auto-complete (e.g. closing brackets added automatically); auto-correct (fixes common typing errors). For initial error detection: dynamic syntax checks — errors highlighted as the code is entered, so mistakes are caught instantly. For presentation: prettyprint / syntax highlighting (distinct colours for keywords, strings, comments, variables); expand and collapse code blocks; auto-indentation; code comments, which are not executed but document the code’s purpose. For debugging: single stepping; breakpoints; report window / variable watch window; variable expressions. SME’s definition of an IDE is worth having for a “what is an IDE” opener: software providing a comprehensive, integrated platform to write, edit, compile, debug and manage code efficiently — it may be a downloaded app or web-based.