F453 Computer Hardware Unit
Contents
Introduction .............................................................................................................................. 1
About ........................................................................................Error! Bookmark not defined.
Functions of Operating Systems (3.1) ................................................................................... 2
Symbols used in this book: .................................................................................................. 2
A) Features of Operating Systems ................................................................................... 3
Fetch Execute Cycle ........................................................................................................... 4
B) Interrupt Handling............................................................................................................ 5
C/D) Memory Management .............................................................................................. 6
Extension Questions: ............................................................................................................ 9
F) File Management .......................................................................................................... 10
Boot Files.............................................................................................................................. 10
ROM and the Boot File ...................................................................................................... 11
File Management .............................................................................................................. 11
File Allocation Tables ......................................................................................................... 12
The Directory Table ........................................................................................................ 12
End of Unit Recap.................................................................................................................. 13
Additional Notes ................................................................................................................ 13
Introduction
This book is designed to teach the F453 unit of the OCR Specification. I have used the marking
criteria from the OCR Scheme of Work to highlight the areas that you need to know. You should
use this book alongside the classroom activities to complete.
IT IS NOT a full and complete guide, in a number of places you will see extension tasks which are
designed for higher grades to make sure you thoroughly understand a topic, if you want a grade
higher than a B, I suggest you do these.
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F453 Computer Hardware Unit
Functions of Operating Systems (3.1)
By the end of this section you should be able to describe:
A. describe the main features of operating systems – for example, memory management,
scheduling algorithms;
B. 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);
C. define and explain the purpose of scheduling, job queues, priorities and how they are used
to manage job throughput;
D. 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. describe spooling, explaining why it is used;
F. describe the main components of a typical desktop PC operating system, including the file
allocation table (FAT) and how it is used, and the purpose of the boot file.
Symbols used in this book:
Whenever you see this image it is a dictionary definition or keyword
you need for this course
When you see this image, it requires you to find definitions from the
internet, but also describe what this term means in your own words/full
sentences.
When you see this image, this is a class activity that you must
complete, usually a diagram and a definition.
This is an extension task. It is optional, but will help you in the exam
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F453 Computer Hardware Unit
A) Features of Operating Systems
All computers need an operating system to run. After looking at the powerpoint, complete the
tasks below.
Define: What is an Operating System
Define: The main features of an operating system
Revision: types of Operating System. Use the worksheet to complete the descriptions of the
different types of operating system. Different operating systems can be used for different tasks,
you can’t use Windows for everything, it is important to remember that.
Operating System Type
Batch Processing
Interactive
Processing
Real Time
Network
File Management
Disk Operation
System
Single User
Multi Programming
Multi User
Multi Tasking
Distributed
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Description
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F453 Computer Hardware Unit
Fetch Execute Cycle
All Operating Systems have to adhere to the Fetch Execute cycle of the processor. The job of the
operating system is to make best use of the processing type available.
In the space below, draw out the steps of the fetch-execute flowchart
For Next Lesson (Research the purpose of Interrupts in the operating system)
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F453 Computer Hardware Unit
B) Interrupt Handling
What is the purpose of an interrupt?
Name the 5 different types of interrupt service routine (ISR)
No
Type
Description
1
2
3
4
5
In the space below, draw out the steps of the Interrupt Service Routine. Make sure that you
explain the key points and key terms.
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F453 Computer Hardware Unit
C/D) Memory Management
Describe how memory looks in the computer when filled with tasks
My Memory Block
Description
Define the following terms:
Disk Thrashing/Threshing
Virtual Memory
What is the difference between memory and disk storage?
Memory
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Disk Storage
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F453 Computer Hardware Unit
What is the purpose of memory Management?
Methods of Memory Management
Describe in the space below the different ways that the operating system manages memory.
Partition Memory
Description of how it works
Diagram (If needed)
Paging
Description of how it works
Diagram (If needed)
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F453 Computer Hardware Unit
Time Slicing
Description of how it works
Diagram (If needed)
Segmentation
Description of how it works
Diagram (If needed)
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F453 Computer Hardware Unit
Spooling
Description of how it works
Diagram (If needed)
Extension Questions:
What would happen if the operating system did not contain memory
management features?
Why are there different methods of Memory Management?
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F453 Computer Hardware Unit
F) File Management
Revision: Label the structure of the hard drive.
Boot Files
Boot files are used for when you start the computer, they are a set of commands used to tell the
computer what to do. Kind of like a simple computer program that points to the right files. Look at
the following Boot file and describe what it is doing:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
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F453 Computer Hardware Unit
ROM and the Boot File
There is a big difference between ROM and the Boot file. ROM is the hardware check. It is there to
establish what each of the parts of the computer hardware is and what it does.
Go into the BIOS in your computer at home (usually by pressing F10 or ESC), have
a look at it and detail below what kind of things are in there (Don’t change
anything unless you want a broken computer!)
File Management
File Management is a way of organising all the storage that we have so that it is easier for people
to find information.
What ways can you think of to store information so you can find it more easily.
Challenge:
You are the network manager in a school with 800 students and 50 teacher and you have been
given a hard drive to partition to make sure there is enough space to store all the data on the
network. You have 100gb to organise and have the following sections:
 Boot and server files
 Programs (this is software that is distributed to the rest of the network)
 User Profiles
 User Data
 Print Spooling Files
If any of these becomes overloaded, the server will crash, so you have to be careful of how you
allocate your space.
Define: Tree Structure
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F453 Computer Hardware Unit
File Allocation Tables
File allocation Tables are not part of the processor and hardware, but part of the Operating
System. They are used to manipulate the Hardware to make it more effective. There are lots of
different file allocation tables, e.g. NTFS, FAT, FAT32 but they all have the same principals.
The idea is that data is stored all over the hard drive; the purpose of the FAT is to number each
cluster of memory so that data can be accessed quickly.
Write the structure of a File Allocation Table
The Directory Table
Cluster 30030
myfile
.doc
Hidden,
system,
archive,
directory, R/O,
Volume
23/05/1979
30 Kb
What is the difference between the directory table and the file allocation table
Directory Table
File Allocation Table(FAT)
Extra task
Find out why we have different File Storage Methods. What is the difference between NTFS, FAT
and FAT 32 and what is the point?
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F453 Computer Hardware Unit
End of Unit Recap
The main focus of this unit is how the hardware and the software work together to organise
themselves to make the computer the most efficient it can be. There is no use buying the most
amazing hard drive, if the Operating System can’t talk to it in a way it understand, this is the battle
between hardware and software.
Additional Notes
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F453 Computer Hardware Unit
End of Unit Extension Tasks
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F453 Computer Hardware Unit
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F453 Computer Hardware Unit
http://abstrusegoose.com/470
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