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answer all questions.

2 Computer Architecture Give the circuit diagram and describe the operation of the following types of memory cell: (a) bipolar memory cell (static) [5 marks] (b) MOS memory cell (static) [5 marks] Give the key characteristics of each of the following types of memory: DRAM, ROM, PROM, EPROM and EEPROM. [2 marks each] CST.96.13.2 3 Digital Communication I Operations of similar functionality can be performed at different layers of a protocol stack. Discuss this in relation to (c) error recovery [4 marks] (d) flow control [4 marks] (e) synchronization [4 marks] 4 Graphics What are homogeneous coordinates? [5 marks] How can they be used in computer graphics to model (a) translation? [5 marks] (b) simple perspective? [10 marks] 5 Business Studies What is meant by SWOT analysis? [5 marks] A small computer company with strong and innovative hardware expertise is considering manufacturing a network interface computer (NIC). The device, which would sell for about half the current price of a PC, is based on games console technology, with a built-in modem. It would allow a user to convert his or her television to a web-browser. Apart from a small amount of parameter storage, the proposed device contains no disc or other long-term memory. How would you determine the market for such a device? [5 marks] Perform an analysis of this opportunity. What advice would you give the company? [5 marks] Comment on changes to the business model that may be expected to be caused by the rapid development of the Internet. [5 marks] CST.96.13.3 6 Programming in C and C++ A grand debate is being planned by a society that has among its members a large number of computer professionals and working programmers. The motion to be put is "That the languages C and C++ should be consigned to outer darkness and their use banned in all serious computer projects". Prepare as your answer to this question a briefing document that could explain to people intending to attend the debate what the major points both for and against C and C++ will be, and the lines of arguments that are liable to be used to show how important they are. You are not required to come down either in favour of or against the languages (but may if you wish). [20 marks] 7 Compiler Construction Programming languages are usually compiled into the machine code of the target computer, but sometimes an interpretive system is used. Discuss the relative merits of these two approaches. [7 marks] Outline the key features of the design of an interpretive code that would be suitable for an implementation of the C programming language and describe the overall structure of an interpreter for it. [7 marks] What techniques could be used to improve (a) the space efficiency, and (b) the time efficiency of interpretive codes? [6 marks] 8 Prolog for Artificial Intelligence Describe how lists that are represented by difference lists may be concatenated (or "appended") in constant time. [6 marks] Define a procedure rotate(X,Y) where both X and Y are represented by difference lists, and Y is formed by rotating X to the left by one element. [14 marks] Data Science (djw1005) (a) In a COVID vaccine trial, n0 subjects were given a placebo and n1 were given the vaccine; x0 of the placebo subjects developed the disease and x1 of the vaccinated subjects. Considering the probability model Xk Binomial(nk, pk), the vaccine efficacy is defined to be e = 1 p1/p0. (i) State the maximum likelihood estimators for p0 and p1. Give a formula for the maximum likelihood estimator for e. [2 marks] (ii) Explain how to compute a 95% confidence interval for e. Also explain how to test whether e > 0.5. [7 marks] (b) Further data about the trial has been made available, and we learn that subjects weren't all enrolled for the same length of time. We are given a full dataset consisting of three features, the predictor variable di and the response variables (ti , ci) for subject i. Here di = 1 if the subject received the vaccine and di = 0 otherwise; ci = 1 if the subject developed the disease and ci = 0 otherwise; and ti is the day on which the subject developed the disease if ci = 1, and the number of days enrolled in the trial otherwise. Consider the following probability model. Among vaccinated subjects, the vaccine is effective with probability f and ineffective otherwise. Effectively vaccinated subjects never get the disease. For ineffectively vaccinated subjects, and for subjects on placebo, each day there is a probability q of developing the disease. The parameters f and q are unknown. (i) For a subject i who received placebo, give an expression for the likelihood of the pair (ti , ci). [4 marks] (ii) For a subject i who received the vaccine, give an expression for the likelihood of the pair (ti , ci). [4 marks] (iii) Give an expression for the log likelihood of the entire dataset. [3 marks] [Note: Your answers to this question should be symbolic. But you may like to know that in the low-dose part of the Oxford-AstraZeneca trial, n0 = 1374, n1 = 1367, x0 = 30, and x1 = 3.]

1. Define analog transmission. 2. Define carrier signal and its role in analog transmission. 3. Describe digital-to-analog conversion. 4. Which characteristics of an analog signal are changed to represent the digital signal in each of the following digital-to-analog conversion? a. ASK b. FSK c. PSK d. QAM 5. Which of the four digital-to-analog conversion techniques (ASK, FSK, PSK or QAM) is the most susceptible to noise? Juxtapose your answer. 6. Define constellation diagram and its role in analog transmission. 7. What are the two components of a signal when the signal is represented on a constellation diagram? Which component is shown on the horizontal axis? Which is shown on the vertical axis? Data Science (djw1005) (a) Let xt be the number of new COVID infections on date t. We anticipate approximately exponential growth or decay, xt+1 (1 + )xt , and we would like to estimate from a dataset (x1, . . . , xT ). (i) Find the maximum likelihood estimator for for the model Xt+1 Poisson

(a) For IPv4 ISPs, each domestic installation typically gets a /32 network. You have a complicated configuration requiring NAT and multiple IPv4 subnets. (i) Why would an IPv6 based provider allocate four /64 networks for your premises when each /64 represents 264 addresses? [2 marks] (ii) A colleague has IPv6 with another provider; they only allow one /64 for each domestic installation. In the past your colleague has used a NAT and many IPv4 private address blocks, but keenly adopted IPv6 permitting them to upgrade their home network. They are now using blocks of the allocated /64 and a router in their home to interconnect the subnets. Not everything is working as they hoped; for example, sometimes IoT devices can't connect to the Internet to update and your colleague can not connect to their front-door camera when at work. Explain what sort of problems your colleague may face along with methods by which they could verify the root cause. [6 marks] (iii) Explain to your colleague why you might not be able to lend them one of your /64 allocations, even though the /64 blocks (provided to you by your ISP) are each globally routable addresses. [2 marks] (b) A local area network may carry several different LANs simultaneously; such a network would be designated for known sets of HomePlug devices. Describe a physical line coding approach for the HomePlug devices that: allows two or more simultaneous virtual local area networks to fairly share the same physical channel, but does not permit trivial interception of network traffic. Outline your approach along with its benefits and drawbacks, comparing it with the simplest use of VLAN tags in Ethernet. [10 marks]

Propose a cause of this fault and outline a test-strategy that could be used automatically to detect such a fault. [4 marks] (b) A user would like to infer the path between two hosts; they suggest using the utility ping. Make your argument for why traceroute is the more appropriate utility, comparing and contrasting their operation. [4 marks] (c) Consider the test network below; Y and Z are two unix IPv4 hosts, while nodes A through E represent fully-conformant IPv4 routers providing the only connectivity between the two hosts. Y Z A E B D C Per-packet load balancing by A and E means packets may be sent on any valid path. No firewalls or packet filtering is used anywhere in the network. (i) Using traceroute infers the following paths: (Y-A-B-C-E-Z), (Y-A-D-E-Z), (Y-A-B-D-E-Z), and (Y-A-B-E-E-Z) Explain (with diagrams as appropriate) why these results have occurred and identify the two true and two false results; [8 marks] (ii) A firmware upgrade for routers A and E means they now do per-flow and not per-packet load balancing. Despite the functions of the flow-based load balancing, traceroute results have not changed; two false paths are inferred along with two true paths. Explain this outcome and a strategy to identify only true paths. [4 marks]