UNIVERSITY OF MALTA THE MATRICULATION CERTIFICATE EXAMINATION INTERMEDIATE LEVEL COMPUTING May 2011 MARKING SCHEME MATRICULATION AND SECONDARY EDUCATION CERTIFICATE EXAMINATIONS BOARD 1 A1 a. 1 mark per correct line A B C D 0 0 1 1 0 1 0 1 0 1 1 0 0 0 0 1 1 1 1 1 b. A Half-Adder. A2 A3 1 c. Adds two bits received at A and B and produces the sum at C and the 1 carry at D. a. A+B using either a Karnaugh map or Boolean algebra (Distributive law, 4 Laws of Tautology, Laws of Absorption) b. A B 2 a. 3 Three from: • Batch – controls a job from beginning to end; • Online – controls Internet-based applications; • Multi-access – controls multiple users accessing same resource; • Real time – controls the immediate processing of data. b. Outline of the interaction of any one of the above. Eg. Batch – no 3 interaction whatsoever because all data that is required for processing is available in system. A4 a. Components of CPU are the CU, ALU and Registers. 3 3 b. Main memory Register Register Secondary storage A5 a. Sort practical example mainly involves the efficiency to search. b. Insertion sort introduces an item at a time ensuring it’s correct place. 2 2 2 Bubble sort compares neighbouring items and swaps them if necessary. A6 A7 A8 a. i. System and Application. ii. System – controls how the computer works + suitable example. Application – performs productive tasks + suitable example. 2 1 1 1 a. 1 A form of learning (education) through the use of computers connected to the Internet. ii. Advantage – Students move at their own pace or other relevant advantage. Disadvantage – No tutor-student interaction or other relevant disadvantage. b. Example - WebCT, Moodle or other relevant example (1 mark) + description (1 mark). c. Remote access is the ability to get access to a computer or a network from a remote distance. i. a. a. 2 2 1 i. -128 to 127 ii. -12 = 11110100 95 = 01011111 i. A law to protect personal information that needs to be processed either manually or by a computer. ii. Data protection commissioner – person who enforces the act. Data controller – legal person who controls and is responsible for the keeping and use of personal information. 1 2 1 Internet – large network of networks i.e. connects millions of computers together globally (the hardware infrastructure). WWW – way of accessing the information over the Internet. 1 1 1 1 b. URL – global address of some information on the WWW + example. 2 c. 1 1 A10 a. i. Server – a computer system or program running a service/s. ii. Proxy server – server that acts as an intermediary for requests from clients seeking resources from other servers • • • • Improved data consistency and portability. Control over data redundancy. Greater security. Less need of maintenance. b. Flat - any database which exists in a single file in the form of rows and columns, with no relationships. Relational – database with tables linked together. B1 1 b. Data within the range + valid example Data outside the range + valid example Data at the boundaries of the range + valid example b. A9 2 a. 1 1 1 1 1 1 The SDLC gives the developer a methodical and sequential well-defined 2 set of well-tested and proven-to-work sequence of stepwise activities and responsibilities that build on top of each other 3 b B2 Top-down approach – breaking down of a system to gain insight into its compositional sub-systems. Bottom-up approach – pieces together small systems to give rise to grander systems, thus making the original systems sub-systems of the emergent system. Pseudo-code method – compact and informal high-level description of a computer programming algorithm that uses the structural conventions of a programming language, but is intended for human reading rather than machine reading. Flowchart method – is a type of diagram that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting these with arrows. c. Three from: • Reuse; • Manageable; • Maintainable; • Defined responsibilities; • Individual component testing; • Ease to manage. d Two stages before from: Domain research, requirements specification and Functional analysis + purpose of each stage Two stages after from: Implementation, testing and maintenance. + purpose of each stage a. LAN – office, school, etc. MAN – city, large campus, etc. WAN – country to country, etc b. i. Physical design of a network and how data is actually transferred in a network. ii. Bus: Each computer or server is connected to the single bus cable through some kind of connector. Ring: Set up in a circular way where data travels around the ring in one direction and each device on the right acts as a repeater to keep the signal strong as it travels. Star: Each network host is connected to a central hub. Mesh: Whose nodes are all connected to each other. iii. Bus: If the network cable breaks, the entire network will be down. Ring: The network is dependent on the ability of the signal to travel around the ring. Star: The central hub represents a single point of failure. Mesh: Too costly and complex. c. i. A way of sub-dividing a communications system into smaller parts called layers. ii. 1 1 1 1 6 4 4 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • Physical Layer: defines the electrical and physical specifications for devices. Data unit: Bit. 1 4 • • • • • • Data Link Layer: provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical Layer. Data unit: Frame. Network Layer: provides the functional and procedural means of transferring variable length data sequences from a source host on one network to a destination host on a different network. Data unit: Packet. Transport Layer: provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. Data unit: Segments. Session Layer: controls the connections between computers. Data unit: Data. Presentation Layer: establishes context between Application Layer entities, in which the higher-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. Data unit: Data. Application Layer: interacts with software applications that implement a communicating component. Data unit: Data. 1 1 1 1 1 5