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3. Advanced Theory
A section of Computer Science, 9608
Listing 10 of 228 questions
An operating system (OS) uses a memory management technique called paging. Explain what is meant by the following terms. Page Page frame Page table Explain why an operating system needs to use scheduling algorithms. State what is meant by an interrupt. For a computer system using multi-programming, the low-level scheduler decides which process will get next use of the processor. One algorithm could be a round-robin, which means every process gets use of the processor in sequence for a fixed amount of time (time-slice). For a round-robin algorithm, five processes are currently loaded and get the use of the processor in the sequence: JOB21 – JOBSS – JOBPT – JOB32 – JOB42, then return to JOB21 Process JOB32 has just completed its time-slice. The following paragraph describes what happens next. Complete the paragraph by inserting the missing processes. Interrupt received from the low-level scheduler. Save all register contents for . Copy the saved registers for to the CPU. The processor will now process .
9608_w19_qp_31
THEORY
2019
Paper 3, Variant 1
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An operating system (OS) uses a memory management technique called paging. Explain what is meant by the following terms. Page Page frame Page table Explain why an operating system needs to use scheduling algorithms. State what is meant by an interrupt. For a computer system using multi-programming, the low-level scheduler decides which process will get next use of the processor. One algorithm could be a round-robin, which means every process gets use of the processor in sequence for a fixed amount of time (time-slice). For a round-robin algorithm, five processes are currently loaded and get the use of the processor in the sequence: JOB21 – JOBSS – JOBPT – JOB32 – JOB42, then return to JOB21 Process JOB32 has just completed its time-slice. The following paragraph describes what happens next. Complete the paragraph by inserting the missing processes. Interrupt received from the low-level scheduler. Save all register contents for . Copy the saved registers for to the CPU. The processor will now process .
9608_w19_qp_33
THEORY
2019
Paper 3, Variant 3
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This diagram shows how applications P, Q and a software development environment can be run on a virtual machine system. Application P Application Q Software development environment A operating system 1 Virtual machine software / virtual machine monitor B operating system Hardware A operating system 2 State the operating systems labelled A and B in the diagram. A B Application P is executing and requests data from a file. Describe what happens after A operating system 1 has received the data request from the application. A software development company uses virtual machines to produce software. State one benefit to the company. Explain two limitations of this approach. Limitation 1 Limitation 2
9608_w17_qp_32
THEORY
2017
Paper 3, Variant 2
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The following syntax diagrams, for a particular programming language, show the syntax of: • an assignment statement • a variable • a number • a letter • a digit • an operator Variable Assignment statement Variable Digit := Variable Operator Number Letter Number Number Digit Letter A B C Operator + – / The following assignment statements are invalid. Give a reason in each case. A2 = B3 + 123 Reason B3 := B3 – 203 Reason A2414 := A3 * B Reason Complete the Backus-Naur Form (BNF) for the syntax diagrams shown on the opposite page. has been done for you. ::= ::= ::= ::= A | B | C ::= ::= A company develops software. It provides virtual machines for its software developers. The company has a large number of clients who use a wide range of hardware and software. Explain the term virtual machine. Ensure that your answer includes the terms hardware and software. Give one benefit to the company of using virtual machines. Give one drawback to the company of using virtual machines.
9608_s15_qp_33
THEORY
2015
Paper 3, Variant 3
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Questions Discovered
228