OCR A2 Computing: Unit 2509 - Systems Software Mechanisms, Machine Architecture, Database Theory and Programming Paradigms

5.4.1

The Function of Operating Systems

a. Features of operating systems

describe the main features of operating systems: for example, memory management,
scheduling algorithms

b. Scheduling

Job queues and priorities

define and explain the purpose of scheduling, job queues, priorities and how they are used to manage job throughput

c. Interrupt handling

explain how interrupts are used to obtain processor time and how processing of
interrupted jobs may later be resumed, (typical sources of interrupts should be
identified and any algorithms and data structures should be described)

d. Memory management

explain how memory is managed in a typical modern computer system, (virtual
memory, paging and segmentation should be described along with some of the problems which could occur such as disk threshing)

e. Spooling

describe spooling, explaining why it is used

f. Modern personal computer operating systems

describe the main components of a typical desktop PC operating system, including the file allocation table and how it is used, and the purpose of the boot file

describe the main components of a network operating system including transparency,
directory services, security and network printing

5.4.2

The function and purpose of translators

a. Types of translators

describe the difference between interpretation and compilation;

b. Lexical analysis

describe what happens during lexical analysis;

c. Syntax analysis

describe what happens during syntax analysis, explaining how errors are handled

d. Code generation and optimisation

explain the code generation phase and understand the need for optimisation

e. Linkers and loaders

explain the purpose of linkers and loaders

5.4.3

Computer architectures and the fetch-execute cycle

a. Von Neumann architecture

describe basic Von Neumann architecture, identifying the need for, and the uses of,
special registers in the functioning of a processor;

b. Registers: purpose and use

c. Fetch-execute cycle

describe, in simple terms, the fetch/decode/execute/reset cycle, and the effects of the stages of the cycle on specific registers

d. Other machine architectures

discuss other machine architectures including parallel processor systems, their uses, advantages and disadvantages.

5.4.4

Data representation, data structures and data manipulation

a. Floating point binary

demonstrate an understanding of floating point representation of a real binary number

b. Normalisation of floating point binary numbers

normalise a real binary number

c.accuracy and range

discuss the trade-off between accuracy and range when representing numbers

d. Implementation of data structures, including lists, stacks, queues and trees

explain the difference between static and dynamic implementation of data structures, highlighting the advantages and disadvantages of each

describe algorithms for the insertion, deletion and amendment of data items stored in
list, stack, queue and tree structures

e. Searching and sorting

explain the difference between binary searching and serial searching, highlighting the advantages and disadvantages of each

explain the concept of algorithms for implementing a binary search and serial search

explain the difference between the sort/merge methods insertion, quick sort and merging, highlighting the characteristics, advantages and disadvantages of each

describe algorithms for implementing insertion, quick sort and merging methods

5.4.5

Programming paradigms

Types of languages and typical applications

identify a variety of programming paradigms (low level, object-orientated, declarative, procedural and functional)

Features of different types of language

explain with examples, the terms object-oriented, declarative, procedural, and
functional as applied to high level languages, showing an understanding of typical uses

Methods for defining syntax

explain how functions, procedures and their related variables may be used to develop a program in a structured way, using stepwise refinement, Jackson structured programming (JSP) or other similar top-down techniques

describe the use of parameters, local and global variables as standard programming
techniques

explain how a stack is used to handle procedure calling and parameter passing

discuss the concepts, and using examples, show an understanding, of data
encapsulation, classes and derived classes, and inheritance when referring to objectoriented languages

discuss the concepts, and using examples, show an understanding, of backtracking,
instantiation, predicate logic and satisfying goals when referring to declarative
languages

discuss the concepts, and using examples, show an understanding, of list processing,
head and tail recursion when referring to functional languages

explain the concepts, and using examples, demonstrate an understanding of the use of
the accumulator, registers, program counter. Direct, indirect and indexed addressing of
memory when referring to low level languages

using examples, describe the nature and purpose of 3rd and 4th generation
languages

explain the need for, and be able to apply, BNF (Backus-Naur form) and syntax
diagrams.

Note: Candidates will not be expected to use any particular form to present algorithms, but
should be able to write procedural algorithms in some form.
Candidates will not be expected to write or interpret the meaning of simple segments of low
level language code.
A detailed knowledge of the syntax of programming languages is not required

5.4.6

Databases

Database design

describe flat files, network, hierarchical and relational databases

analyse and size a database application

explain the advantages that using a relational database gives over flat files

utilise formalised techniques for designing databases: entity-relationships
diagrams/entity life history

define, and explain the purpose of, primary, secondary and foreign keys

Normalisation and data modelling

design a simple relational database to the third normal form (3NF), defining tables and
views of data

draw entity-relationship (E-R) diagrams to represent diagrammatically the data model

Methods and tools for analysing and implementing database design

design forms for input, deletion, modification and querying of a database

describe the structure of a data base management system (DMBS), including the
function and purpose of the data dictionary, data description language (DDL) and data
manipulation language (DML)

Control of access to relational database elements

explain the importance of varying the access allowed to database elements at different
times and for different categories of user

File access methods

Access rights/ Access control