BCS Level 4 Certificate in IT
Computer and Network Technology
This report is for Sections A and B of the paper. It consists of two sections: 1. Overall comments
2. Detailed questions’ report
1. Overall comments
As in previous sittings, many candidates did not follow instructions and accordingly did not encircle the question numbers at the front of their scripts. Candidates failed to write the question number at the top of every page of the scripts. Centres and course providers must impress this rule on their candidates as omission of vital information causes problems during marking. The level of English was bad in some centres, hence the inability for candidates to express themselves clearly.
While marking scripts from various centres, it was felt that candidates did not seem to have studied the various topics well. Course providers must endeavour to explore this syllabus in depth. Computer and Network Technology is a core aspect of an IT Professional. Gaps in knowledge with regards to this area can pose serious problems in understanding more advanced and specialist IT concepts. If in doubt, course providers must seek clarification from the BCS examinations office.
It was also noted that many candidates did not attempt the correct number of questions. Consequently, they were not able to score enough marks to achieve a pass grade. 2. Detailed questions’ report
It is very unfortunate to note that many candidates and course providers did not analyse past trends for this paper. Some elements of the paper have been examined during previous sittings. If candidates had paid attention to this, they would have been better prepared, and accordingly written good answers. It is also worth mentioning that candidates seemed to ignore the amount of marks allocated to questions in section A and B. When writing answers, candidates must carefully keep in mind that questions 1, 2, 3 and 4 each carries 30 marks. Accordingly, candidates must write sufficiently in-depth answers to attract these marks. Short answers which lack depth did not enable candidates to score well in section A.
The stored program von Neumann digital computer executes instructions in a two-phase fetch/execute mode. Explain what we mean by the expressions stored program and fetch/execute used in this statement.
With the aid of a diagram describe the structure of a digital computer (in terms of registers, buses, and functional units) and explain how instructions are executed. (12 marks)
Describe the machine (assembly language) instructions that are executed by a typical computer. The computer may be a commercially available machine or a conceptual machine that you have studied on your course. Illustrate your answer with several different types (or class) of assembly language instruction to demonstrate the range of operations these instructions may carry out. (12 marks)
a) A stored program computer is a machine in which the program and data share the same memory. The notion of a stored program computer dates back to the mid 1940s and is associated with von Neumann (von Neumann and stored program computer are interchangeable). Most computers we use today are stored program machines. However, because data and instructions are cached in separate memories in high-performance microprocessors, some people could say that today’s computers are no longer truly stored program machines.
Because data and program (instructions) reside in the same memory it is necessary for a computer first to read an instruction from memory, to decode it, and then to read and data it needs from memory (or write a result back to memory). Thus, you can say that each instruction has a fetch phase and an execute phase requiring two accesses to memory per instruction. This mode of operation gives rise to the so-called von Neumann bottleneck because of...