System Software: practice questions

Question 1

A user's hard disk drive has been used for several years to save, edit and delete many different files. As a result, the data belonging to some files is no longer stored in one continuous section of the disk. Instead, each of these files has been split into several smaller piece…

Accepted Answer

B

Question 2

Which one of the following is NOT a management function carried out by a computer's operating system?

Accepted Answer

C

Question 3

Riverbank College's library has a single shared computer that runs a multitasking operating system. One afternoon, a student called Elif logs in and opens a web browser, a word processor and a spreadsheet program all at the same time, switching between them as she researches and…

Accepted Answer

((a)) The operating system keeps track of which areas of main memory are free, allocates a separate area of memory to each of the three programs when it starts, and prevents one program from accessing or overwriting the memory allocated to another. This is why the three programs can r…  ((b)) The operating system's process management rapidly switches the processor between the three running processes, giving each one a short turn of processor time in quick succession, so that each program appears to run continuously even though only one is actually being executed at a…  ((c)) The operating system places each print job into a queue (spools it), and sends the queued jobs to the printer one at a time, in the order they were received, so Tom's document prints first, followed in full by Elif's document, instead of the two being merged or one being lost.  ((d)) The interface lets a user start a task, such as printing a document, by clicking an icon, button or menu option, without needing to know any low-level hardware detail, such as the printer's specific control commands or how data is transferred to it.

Question 4

Jamal shares a family laptop with his younger sister Aisha. Each of them logs in to their own separate user account, protected by its own password. Jamal keeps his growing collection of coursework documents organised inside several folders on the laptop's hard disk, but he has n…

Accepted Answer

((a)) The operating system's file management lets Jamal create named folders and store files inside them, building up an organised folder structure. It keeps a record of each file's name and its exact location on the hard disk, so that when Jamal later wants to open a file, the operat…  ((b)) The operating system keeps track of which user account is currently logged in, and links access rights to that specific account. Files created under Jamal's account are only accessible when Jamal himself is logged in; when Aisha logs in under her own separate account, she is not…  ((c)) Backup software. It makes a copy of Jamal's files (or the whole system) onto separate storage, such as an external hard disk or cloud storage, at regular intervals, so that if the laptop's own hard disk fails or the files are lost, deleted or corrupted, Jamal can restore his cou…  ((d)) A program library is a collection of pre-written, already-tested subroutines/routines that provide common functionality, which a programmer can call from within their own program instead of writing that code themselves. Jamal uses the ready-made graphics routine because it saves…

Question 5

Priya is writing a new game in a high-level programming language. While she is still developing and testing the game, she runs her code through an interpreter, so that she can try out small changes immediately. Once the game is finished, she instead uses a compiler to produce a…

Accepted Answer

((a)) An assembler translates a program written in assembly language into machine code (object code) that the processor can execute directly.  ((b)) The compiler translates the entire source code of Priya's finished game into object code (machine code) in one go, before the game is ever run, producing a stand-alone executable file. Once compiled, this object-code file can be run directly by the processor without the compiler…  ((c)) The interpreter translates Priya's source code one statement at a time: it translates a single statement, immediately executes it, and only then moves on to translate and execute the next statement. It does not produce or save a separate object-code file; the interpreter and the…  ((d)) Three valid differences: (1) a compiler translates the whole program before any of it runs, while an interpreter translates and executes one statement at a time as the program runs; (2) a compiler collects and reports all the syntax errors it finds across the whole program toget…

Question 6

Aiden has just bought a brand-new external hard disk drive. It has never been used before and currently has no file system on it at all, so his computer's operating system cannot yet use it to store any files.

Which utility program must Aiden run on the new disk before he can start saving files onto it?

Accepted Answer

A

Question 7

A small design studio buys a new graphics tablet, a peripheral device that lets an artist draw directly onto the screen instead of using a mouse. When the tablet is first connected to a computer, the operating system cannot yet control it correctly, until a particular piece of s…

Accepted Answer

((a)) A device driver (driver software).  ((b)) Different types of peripheral device work in different, specific ways and need different low-level control signals to operate correctly. A generic command that suits one device might not be understood, or might not work correctly, on a completely different type of device, so a s…  ((c)) Even though both are graphics tablets, different makes are built differently internally and expect different specific control signals. A device driver is written for one particular device, so it does not know the specific commands needed by a different make of tablet, and would…  ((d)) The operating system lets application software make a generic request, such as reading position input from a tablet, without needing to know the low-level detail of each specific tablet model. The correct device driver, once installed for a particular tablet, translates this gen…

Question 8

Bilal receives an email from an address he does not recognise, with a file attached that he was not expecting. Before opening the attachment, he lets his antivirus utility scan the file first. (a) Describe how an antivirus utility can identify that a downloaded file contains mal…

Accepted Answer

((a)) The antivirus utility holds a database of virus signatures, short, distinctive patterns of code taken from known malware. It scans the downloaded file's own code and compares it against every signature stored in this database; if a matching pattern is found, the file is identifi…  ((b)) Any two of: quarantine the file (isolate it in a secure area so it cannot run or affect the rest of the disk); delete the file; warn/alert the user and prevent the file from being opened or run.  ((c)) New malware is being written constantly, and each new piece of malware has its own new signature pattern that will not yet be in an older database. If the database were never updated, the antivirus utility could only recognise older, already-known malware, so it needs regular up…  ((d)) For example, a file downloaded from a website, or a file copied from a USB flash drive. Scanning only email attachments would not fully protect Bilal's computer because malware can reach a computer through many other routes too, such as a website download or removable storage, s…

Question 9

Some high-level programming languages, such as Java, are described as "partially compiled and partially interpreted", rather than being purely compiled or purely interpreted.

Which of the following best describes what actually happens when a program written in such a language is translated and run?

Accepted Answer

A

Question 10

Farah is a first-year student teaching herself to program, using an Integrated Development Environment (IDE) rather than typing code straight into a plain text editor. (a) Farah starts typing the name of a built-in function, and the IDE immediately shows her a list of matching f…

Accepted Answer

((a)) This is a context-sensitive prompt (code completion). It helps Farah by showing her a list of valid matching function names and the parameters each one expects as she types, without her needing to look them up separately, which speeds up writing code and helps her call the funct…  ((b)) This is an example of initial error detection (dynamic/real-time syntax checking). It has detected a syntax error, code that breaks the grammatical rules of the programming language, and flags this immediately as Farah types, rather than only being found later when she tries to…  ((c)) Two presentation features: prettyprint, which automatically re-indents code and applies consistent colour-coding to keywords, variable names, and so on, to make it easier to read; and code folding, which lets Farah collapse (hide) a block of code, such as the inside of a procedu…  ((d)) Farah sets a breakpoint on a line of code where she suspects the problem might already have occurred; when she runs the program, execution automatically pauses at that line rather than running straight to completion, letting her inspect the current values of her variables at tha…

System Software: Computer Science 9618 (Cambridge International AS & A Level)

Syllabus coverage

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10