Describe a scheduling algorithm with the following properties:…Describe a scheduling algorithm with the following properties: favours I/O-intensive processes responds dynamically when processes change their behaviour: e.g. enter a compute-bound or I/O-intensive phase has acceptable context switching overhead avoids inde?nite overlook (starvation) of a process[7 marks](b) In order to carry out its functions, a ?ling system holds metadata on each stored object.(i) What is this metadata likely to comprise? [6 marks](ii) Describe the directory service functions of a ?ling system, including how the metadata is used. [7 marks](a) For Single Precision in the IEEE binary ?oating-point standard (IEEE 754) the precision is de?ned as 24, and the exponent requires 8 bits of storage. With reference to IEEE Single Precision, explain the terms exponent, signi?cand, precision, sign bit, normalised number denormal number. [6 marks](b) Explain the term hidden bit. What are the values of the hidden bit for normalised and denormal numbers? How is the exponent stored and why? How are the exponent, signi?cand and sign bit arranged in memory? [4 marks](c) Let x* denote the ?oating-point representation of a number x. De?ne the terms absolute error (ex) and relative error (dx) in representing x. How are ex and dx related? De?ne machine epsilon (em). [3 marks](d) Assume dx = dy = dz = em. Using worst-case analysis, estimate dxy, exy. Find an expression for dw where w = z-xy. [4 marks] (e) Working to 4 signi?cant decimal digits only, compute w* when x* = 2.018, y* = 2.008,z* = 4.058. Given em ‘ 0.5×10-3, how many signi?cant decimal digits of w* can be relied on? [3 marks]8 Mathematics for Computation TheoryLet A,B,C be sets. De?ne the Cartesian product (A×B) and the disjoint union (A + B). [3 marks]Let f ? (A×B),g ? (B×C) be relations between A and B, B and C respectively. De?ne the inverse relation f-1 between B and A and the product relation (f ?g) between A and C. [3 marks]What conditions must be satis?ed for the relation f to be a function f : A ? B? [2 marks]Write that (A ? B) for the set of all functions from A to B. If A,B are both ?nite, |A| = a,|B| = b, how many elements are there in (A×B), (A + B), (A ? B)? [2 marks] If f and f-1 are both functions, we say that f is a bijection, and we write A ~ = B. If A,B are both ?nite and f : A ? B is a bijection, prove that a = b. (?) [2 marks] Establish explicit bijections between the following pairs of sets:(a) A ? (B×C), (A ? B)×(A ? C); [3 marks] (b) (A + B) ? C, (A ? C)×(B ? C). [4 marks] If A, B, C are all ?nite, verify that the cardinality condition (?) above is satis?ed in each case. [1 mark]9 Computation Theory(a) What is Turing’s Thesis? [2 marks](b) Explain the action of a Turing machine that is speci?ed by a quintuplet description. [4 marks](c) De?ne the con?guration of a Turing machine at step t, and establish equations that specify the con?guration of a k-symbol Turing machine at step (t +1) in terms of the con?guration at the previous step t. [6 marks]?(d) Explain how you would use your equations to simulate a speci?c Turing machine by a register machine whose program encodes the quintuplet description. To what extent does this support Turing’s Thesis? [Explicit program for a register machine is not required.] [8 marks]Describe an algorithm for performing scan conversion of a set of 3D polygons, including details of clipping, projection, and the underlying 2D polygon scan conversion algorithm. You may assume that you are given the colour of each polygon and that no lighting calculations are required. Please state any additional assumptions that you need to make. Ray tracing is not an acceptable answer to this question. [20 marks]11 Introduction to Security(a) Explain brie?y mechanisms that software on a desktop computer can use to securely generate secret keys for use in cryptographic protocols. [5 marks](b) Give two di?erent ways of implementing residual information protection in an operating system and explain the threat addressed by each. [5 marks](c) Consider the standard POSIX ?le-system access control mechanism:(i) Under which conditions can ?les and subdirectories be removed from a parent directory? [2 marks](ii) Many Unix variants implement an extension known as the “sticky bit”. What is its function? [2 marks](iii) On a POSIX system that lacks support for the “sticky bit”, how could you achieve an equivalent e?ect? [2 marks]Consider the following four documents that would have improved projects such as the Cambridge University CAPSA project or the London Ambulance Service system:(a) a plan for managing development risk;(b) a safety and reliability speci?cation;(c) a user requirements document;(d) a test speci?cation.Describe each of these four documents, including how you would gather the data to write the document; the main sections of the document; who must read that document; who should approve the document; and how the CAPSA and London Ambulance Service projects di?er in the e?ect this document would have had. Computer ScienceEngineering & TechnologyObject-Oriented Programming FIN 650
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