Computer System Architecture and Components

This report delves into the intricacies of computer system architecture, covering topics such as data representation, processor operations, and memory types. It explains concepts like RISC and CISC architectures, polling, interrupts, and the fetch-execute cycle.

Computer system Architecture

Contents
Introduction.................................................................................................................................. 3
LO1Understand how data can be represented within computer systems.....................................4
P1 explain using examples how numeric and alphanumeric data can be coded within a
computer system......................................................................................................................4
P3 convert numeric data between different number systems including floating point...............8
P4. Carry out Boolean logic operations..................................................................................12
LO2Understand the functions of computer system components................................................13
P5 illustrate the key computer system components and how they interact.............................13
P6 explain the different types of memory that can be attached to a processor.......................18
P7 explain how polling and interrupts are used to allow communication between processor
and peripherals...................................................................................................................... 21
LO3 Understand the principles of processor operations............................................................22
P8 compare Reduced Instruction Set Computer (RISC) chips and Complex Instruction Set
Computer (CISC) chips..........................................................................................................22
P9 illustrate the use of the different processor registers in the fetch-execute cycle................25
Conclusion................................................................................................................................. 28
References................................................................................................................................ 30
List of figures:
Figure 1 Boolean logic operations..............................................................................................12
Figure 2 Block diagram of Computer system component...........................................................14
Figure 3 input unit...................................................................................................................... 15
Figure 4 output unit.................................................................................................................... 16
Figure 5 memory unit................................................................................................................. 17
Figure 6 CPU............................................................................................................................. 18
Figure 7 different types of memory............................................................................................19

Figure 8 RISC and CISC architecture........................................................................................23
Figure 9 fetch-execute cycle......................................................................................................26
Introduction
In this report, I will discuss how alphanumeric and numerical data will be encoded in a
computer system. I will discuss numeric data, alphanumeric data and how the computer
understands the given instruction. I will discuss character encoding-ASCII.
Further, I will discuss how different types of data will be stored on the computer. I will
discuss how graphics, images, audio, the video will be stored in a computer system.
This report will contain how numeric data will be converted to different data type like
how binary number change to octal, hexadecimal, floating point. This report will also
contain details about Boolean logic gates and according to that, a truth table will be
generated. A brief discussion will carry about computer system architecture and its
components. After that different types of computer memory will be discussed,
information about interrupts occur when peripheral device interact with each other. I will
discuss different type of instruction set RISC and CISC and will also discuss fetch-
execute cycle.

LO1Understand how data can be represented within computer
systems
P1 explain using examples how numeric and alphanumeric data can be
coded within a computer system
Alphanumeric data are the type of data that contains digits as well as alphabets.
Alphanumerical data is a combination of numerals and alphabets. Alphanumerical data
allows 26 alphabets and 10 numerals for alphanumerical data. We cannot perform
mathematical operations on alphanumerical data. Alphanumerical data is used to store
passwords as they allow writing both numbers and alphabets it makes our password
strong. We can also write some characters in alphanumerical data. For example xy62,
hy65, yu5#
ASCII Code-
Another way of representing the alphanumeric data is using ASCII code. For example,
for A the ASCII code is 65. The computer understands only machine language.
Two's complement
It is a method which is used to change a positive integer number to negative integer
number. This method works as first we calculate one’s complement and then add
one.Example 12 represents 1100 in binary form.Two's complement of 12 is 0100.
Numeric data-
Numeric data are the type of data that contains only digits. Numeric data is always in
form of digits so any form of mathematical operations can be performed on numerical
data like subtraction, addition, division, and multiplication. Numerical data can be
arranged in ascended or descended from. For example 1234, 54 these all are numeric
data.
Binary number-
A binary number is a number which is presented in 0 and 1 form. As computer
understands only 0 and 1 form.

Example 24 represents 11000 in binary form.
Decimal number-
A decimal number is base -10 systems. In decimal number system it has 10 distinct
digits (0-9) for representing any number.
Example 256 is represented in the decimal system as 2*102+5*101+6=200+50+6.
Octal number
An octal number is a representation of number for representing long digit number in
form of a binary number as 0 and 1.It is a base-8 system that uses digits between 0 –
7.Example 8768 is an octal number which has a base-8.
Hexadecimal number
A hexadecimal number is a representation of number for representing long digit number
in form of a binary number as 0 and 1.It contains digits 0 -9 and letters A – F. The
alphabets A –F represents a value from 10 – 15.Example AA is a hexadecimal number
which is equal 10101010 in the binary number system. (Bbc, n.d).

P2 explain using examples how different types of data can be converted
and stored in computer systems
Basically, there are two types of data that are digital and analog data. Digital data is a
discrete type of data whereas analog data is the continuous type of data. Computers
use digital data and in the natural world, analog data are used. In computer system data
is non-continuous for example binary data that is non-continuous.
Graphics and images stored in different resolutions and formats. These all are stored in
form of digital information.An image is transferred in form of digital code and then it
again converted into an image for display. The image is made up of pixels. Pixels are
made up of binary numbers. 1 is for black and 0 is for white. An image is then made up
of binary. To create any image computer first know in advance the size of the image.
This advanced information is known as metadata. For example, if the image is to be
created as 8X8 it means 8 pixels across and 8 pixels down. Image supports many
formats jpeg, png. Png stands for Portable Network Graphics and Jpeg stands for Joint
Photographic Experts Group. Jpeg mostly used for photographs whereas on the other
end png used for an image which is related to the text, lines. Jpeg does not support for
transparency whereas png supports the transparency. For storing the sound in the computer
it needs to be converted into binary for this it needs to convert into a digital signal. The sound is
captured by the microphone and then it converts into a digital signal. Sound quality is dependent
on the time samples between data. As the time sample are close together it increases the
sound quality.The sample rate is defined as the frequency at which samples are taken.It is
measured in terms of hertz (Hz). When static images are played at a high rate a digital image is
formed.Usually, 24 frames per second are for digital frames. It can be up to 100 frames or more.
Digital films are measured in terms of frames rates per second (fps). It can also be measured in
terms of hertz (Hz). It is almost similar to sample rate. The total audio and image processed are
called bit rate. Sometimes it is necessary to compress the video.It can be done by reducing the
resolution, reducing the size, reducing the bit rate. Compression reduces the video quality. This
loss in quality is called artifacts. Compression is usually done to reduce the storage size and
processing time. It reduces the transfer time of the files. If compression is not performed then it
takes a lot of time to upload and download the video files, audio files, text files. Usually,
compression is of two type’s lossless and lossy compression. Lossy compression is

compression where data is lost during compression while lossless compression is the type of
compression where loss of data is not there (Eehawaii, n.d).

P3 convert numeric data between different number systems including
floating point
Decimal to binary
A decimal number includes 10 digits (0 - 9) whereas in the binary system there are only
two digits 0 and 1.
Steps to convert decimal to a binary number:
a. First, write down the decimal number as quotient and divide the quotient by 2.
b. Write down the remainder that is either 0 or 1.
c. Repeat the process until quotient becomes zero.
d. Starting from bottom to up the new number formed is a binary number.
Example 40
Number Remainder
40/2 0
20/2 0
10/2 0
5/2 1
2/2 0
1 1
The binary formed is 101000.
Binary to decimal
Steps to convert binary to decimal number:-
a. First, write down the binary as 0 and 1.
b. Starting from right to left write the power of 2.Start as 20.
c. Increase exponent by one every time as we move from right to left.
d. Continue until when the list is equal to no of digits in the binary number.

e. Write down the value of each exponent.
f. Add those values which have corresponding 1.
g. The final value after addition is decimal number.
Example 10100.
1 0 1 0 0
24 23 22 21 20
16 8 4 2 1
16+4=20
101002=20
Decimal to hexadecimal
Hexadecimal number includes sixteen numeral system. A, B, C, D, E, F,
0,1,2,3,4,5,6,7,8,9.
Steps to convert decimal to the hexadecimal number system.
a. Divide the decimal number by 16 until remainder less than 16 obtains.
b. Convert the remainder directly to hex as remainder<16.
c. The answer is then again divided by 16.
d. repeat until the answer is less than 16.
e. From bottom to top write the number that will be a hexadecimal number.
Example 256
255/16=15 remainder=15
The hex number is FF.
Hexadecimal to decimal

Steps to convert hexadecimal to decimal:-
a. First, write down the hexadecimal number.
b. Starting from right to left write the power of 16.Start as 160.
c. Increase exponent by one every time as we move from right to left.
d. Continue until when the list is equal to no of digits in the hexadecimal number.
e. Write down the value of each exponent.
f. Multiply each digit by a hexadecimal number by corresponding exponent 16.
g. The final value after addition is decimal number.
Binary to Floating point
Steps to convert binary to floating point:-
Example 2.25
a. The integral part is easy, 210 = 102. For the fractional part:
0.250 × 2 = 0.5 0 Generate 1 and continue.
0.50 × 2 = 1.0 1 Generate 0 and continue.
b. So 0.25010 = 0.102, and 2.62510 = 10.012.
c. Add an exponental part: 10.012 = 10.012 × 20.
d. Normalize the mantissa part: 10.012 × 20 = 1.0012 × 21.
e. Mantissa: 001
f. Exponent: 1 + 3 = 4 = 1002.
g. Sign bit = 0.
2.25 represents as 4116

Floating to binary
Steps to convert floating to binary
a. Integral part is directly converted to binary.
b. Fractional part is converted as
0.250 × 2 = 0.5 0 Generate 1 and continue.
0.50 × 2 = 1.0 1 Generate 0 and continue.
c. And then it is reversed.
Example 4.5
4=1002
.5*2=1
4.5=100.12 (Cs ).

P4. Carry out Boolean logic operations.
Figure 1 Boolean logic operations
.A B C D E
0 0 0 0 1
0 0 1 0 1
0 1 0 0 1
0 1 1 0 1
1 0 0 0 1
1 0 1 0 1
1 1 0 0 1
1 1 1 1 0
In the first operation and gate output is 0 then it is operated with 0 the whole output is
0.Then it is pass to nor gate so result E become 1.
Same for other 6 operations the output is 1 (Bbc, 2018).
For eight operations the first and gate operation result is 1.Then it is operated in second
and gate the result is 1.Then it is passing to nor does gate the result become 0 (Doc,
2016).

LO2Understand the functions of computer system components
P5 illustrate the key computer system components and how they interact
Computer System
It can be termed as the fusion of hardware and software. The software part completely
relies on the configuration of the hardware. Some basic terms:
1. Hardware – These are the physical electrical units which consist of the Input
device, Output device, CPU (Central Processing Unit) and storage devices.
2. Software – Hardware is just the outer electrical piece, software is the thing which
gives the hardware its use. Without software hardware in a computer system is of
no use. The software is a general computer program which performs tasks like
gaming, websites, videos etc. (Mkhisalg, 2018).
Computer System Components –
The architectural design of computer system is different from one model to another but
their basic organization of components is same which also known as functional units.
The complete Computer Architecture design was given by John von Neumann in 1945
(Computer Science GCSE GURU, 2018).
The computer system architecture components as per Von Neumann architecture are –
1. Input unit
2. Output unit
3. Memory unit
4. Registers
5. Central Processing Unit (CPU)
6. Arithmetic and Logical unit (ALU)

Figure 2 Block diagram of Computer system component
1. Input Unit – This is the unit which creates a link between outer environment
source to the inner computer system. The data entered into the system must not
be computed before. The data which is entered depends on the input device from
which it is entered. Further, this input is converted in binary codes which are
understandable by the system's primary memory. This transformation is done by
the input interfaces.
Tasks performed by Input unit –
 Accept or read the data entered by user
 Convert the data to the desired transformation
 Have to forward the transformed data to system

Figure 3 input unit
2. Output Unit – It's the opposite of Input unit. It's the link between inner computer
systems to the outer source environment. The result calculated by the CPU &
ALU is passed to the output unit. It then transforms the data to user
understandable form.
Tasks performed by Output unit –
 Accept or read result by computer
 Convert the result into user understandable form
 Forward the transformed data to Output device

Figure 4 output unit
3. Memory Unit – The result of input units is stored before passing it to the
computer system, similarly the result generated by the computer system is stored
before passing it to the output unit. And the intermediate results produced by
CPU & ALU are also preserved to be computed. It is done by the Storage unit or
primary or system's main memory.
Tasks performed by storage unit –
 Storing data received by the input unit
 Storing the intermediate data
 Storing the result before passing it to output unit

Figure 5 memory unit
4. Registers – These are the smallest and high in speed units for storing the data.
The always must be stored in registers first before it is processed.
Types of registers –
 Memory Address Register (MAR) – It contains the address of memory
location of that data that needs to be processed.
 Accumulator (AC) – Here the result from the logic and arithmetic
processes are stored.
 Memory Data Register (MDR) – It contains the actual data which is being
transferred from or to memory.
 Current Instruction Register (CIR) – It holds the current or present
instruction which is in process.
 Program Counter (PC) – It holds next instruction’s address in it.
5. CPU (Central Processing Unit) – Central Processing Unit is the brain. It’s the
core of any computer system. Its responsible for events and processes. Control
external and internal devices, and does the ALU operations. The microprocessor
performs the instruction set. The control unit and ALU combine called CPU. The
CPU operations are dependent on the processor used like if the instruction set is
complex the processor will become slower.

Figure 6 CPU
6. Arithmetic & Logic Unit (ALU) – The arithmetic & logic unit is the place where
the instruction's execution takes place while processing. Here calculations,
decision, and comparisons are made. It contains various circuits which perform
calculations like addition, subtraction, multiplication, division, comparisons etc. on
data received from the storage unit. The data stored in the storage unit is used
by the ALU, operations are done then if there are intermediate results calculated
then these are sent back to the storage unit for future need.
P6 explain the different types of memory that can be attached to a
processor
Different types of memory –
Memory in computer system plays a vital part for the obvious reasons for storing the
data. A computer would be of no use unless a memory is not connected. The computer
system’s performance depends upon the size of the memory allotted to it (Agrawal,
2012). It is of two type:
1. Primary / Volatile memory
2. Secondary / Non-Volatile memory

Figure 7 different types of memory
1. Primary / Volatile memory – The primary memory is the internal memory of the
system like ROM &RAM, they both form part of system memory. The primary
memory of a system provides the space for the system to process. Included terms in
primary memory are:
 Random Access Memory (RAM) – It's a read-write memory. This memory
randomly a lots any location in the memory and can be used to directly store or
retrieve data. The storage in the RAM is totally random and temporary, if the
system gets shut down the data inside the RAM is gone.
 Read Only Memory (ROM) - Here the storage by the program is permanent. It
stores limited standard data of the program given by the manufacturers for
operating the PC. It can only be read not write by the CPU.
 Programmable Read Only Memory (PROM) – We know that ROM cannot be
changed but in case of PROM a program can be stored in PROM. Once the
programming is done in PROM it cannot be changed.
 Erasable Programmable Read Only Memory (EPROM) – It resolves the
problem faced in the ROM & EPROM. It is like PROM but here one can delete
the information that exists on the EPROM and again rewrite the program. It is
done with the help of Ultraviolet rays which deletes the information in EPROM.
 Cache memory – The speed of the memory in the computer is slower than the
speed of the CPU, that's why the occurrence of mismatch in clock speed can be
there. To overcome this problem a small memory unit is installed between CPU
and main memory. The speed of cache memory is a bit similar to that of CPU.
Cache memory is very fast then the RAM.

 Registers – These are the small delivery units. Registers not part of main
memory. Registers are the units which deliver data from CPU to different units.
2. Secondary /Non-Volatile memory – These are the permanent and external
memory. Secondary memory can be stored in various devices like floppy, hard disk,
CD etc.
 Magnetic tape – These are used for big computers like mainframe computers
where a huge amount of data is to be stored. Here cassettes like devices are
used having magnetic tape to store the data
 Magnetic Disk – It consists of a magnetic disk inside a device which revolves
and the data is stored onto it. Example – hard disk, floppy disks etc.
 Optical Disk – The optical disk are circular disks which hold a large amount of
data onto them. Examples – CD-ROM, WROM

P7 explain how polling and interrupts are used to allow communication
between processor and peripherals
Polling & Interrupt –
Polling – In polling method, a microcontroller must have to access by itself to the
device and should expect information which is needed to be processed. In the polling
method, the external devices are completely dependent on the microcontroller. It is the
process where the controller waits for the connected external device to check for its
state. The drawback of such method is that microcontroller has to wait for the external
device to check its state and to see that there is any new information or not. Continuous
monitoring of a device is done by the microcontroller. The microcontroller performs
checking of each and every device in Round Robin technique, whenever a device’s
condition is met it performs the task and then move on to another device (Milosavljevic,
2011).
Interrupt – The interrupt is a very different method from polling. In this method, a signal
is generated and sent to the microprocessor to mark an event for it. If a device needs
processor it sends interrupt signal to the microprocessor to stop all the ongoing
processes and execute the special code requested by the device. Interrupt Service
Routine (ISR) is the program which is requested to execute by a device (Milosavljevic,
2011).
The biggest advantage of Interrupt is that one microcontroller can give services to
many devices. When an interrupt occurs the microcontroller stores all the ongoing
processes and executes the respective ISR after the completion of ISR microcontroller
again restores and resolves the earlier processes. For each interrupt, there is an
allocation of memory that contains the address of the respected ISR.

LO3 Understand the principles of processor operations
P8 compare Reduced Instruction Set Computer (RISC) chips and Complex
Instruction Set Computer (CISC) chips
The two architectures presently used in computer architecture are CISC (complex
instruction set computer) and RISC (reduced instruction set computer) and the
dissimilarity between this two architecture are their instruction set. CISC computer
architecture has a small instruction set but the instructions are simple to understand
whereas RISC computer architecture has a large instruction set but as the instruction
set is large the instructions are very complex to understand. The main difference
between RISC and CISC is the computer cycles. In CISC architecture the instruction set
is small many instructions are written more than once so the architecture is inefficient
whereas in RISC the instructions are written only once in the code so it is reusable in
the code. CISC is easier to understand but the inefficiency is very high the computer
cycles are wasted as one instruction are written more than once, on the other hand, the
RISC architecture the efficiency is high compared to CISC as the instructions are not
repeated in code.
RISC and CISC architecture have different applications. RISC is preferred when
computer cycles are short.RISC is used in smartphones, tablets whereas CISC is used
in a computer. The implementations of CISC instructions are tough as compare to RISC
architecture.

Figure 8 RISC and CISC architecture
Clock speed also refers to as processor speed. It is defined as the frequency at which
CPU (central processing unit) works.
The Performance Equation
to perform computer’s ability the equation is as follows:-
The CISC tries to reduce instructions per program and ignores a number of cycles
whereas in RISC architecture the number of cycles is reduced and ignores the size of
instructions per program.
The address bus is the computer system architecture that is used to transfer data
among devices which have some physical address (in memory).
In computer system architecture there are many addressing modes:-
1. Immediate addressing mode.

2. Address register direct.
3. Implicit addressing mode
4. Address register indirect mode
a. Immediate addressing mode
In this mode, the operand is written in the instruction itself.
MVI A, 06H
In this instruction, the content 06H is moved to register A.
b. Address Register Direct
In this mode, the content of one register is copied to another register directly.
MOVE A1, A2
In this instruction, the contents of the A2 register is copied to register A1.
c. Implicit addressing mode
In this mode when we have source and destination address fixed we use implicit
addressing mode.
CMA
CMA is the instruction used for the compliment.
d. Address register indirect mode
In this mode, the address of operand field is mentioned in register pair.
MOV A, M
In this instruction the M is registered pair like H-L pair, A is the destination and MOV is
the move instruction.

These all modes are used for transferring data among registers to registers, registers to
memory, memory to register, memory to memory (Techopedia, 2013).

P9 illustrate the use of the different processor registers in the fetch-
execute cycle.
Fetch-execute cycle
This cycle is also known as the instruction cycle. The aim of a CPU is to always execute
the tasks or programs which are assigned to it. This is done by Fetch-execute cycle.
The cycle begins to work as you switch on the computer. To perform the program, it is
first copied to main memory of the system from secondary memory. The program
counter (PC) of the system is first set to the memory address of the program's first
instruction to be run. The program execution begins.
Every instruction of machine code takes a block of memory. Each block of memory has
a unique memory address. All the instruction's address in the program is stored in
program counter and these program counters tell the CPU what to execute and when to
execute. While the program is in execution mode the CPU performs the fetch-execute
cycle which repeats in a loop until a STOP instruction is reached (Bbc, 2018).
Figure 9 fetch-execute cycle
Components used –

1. The program counter (PC) – A program counter is that register which stores
the next program step or instruction’s address which is going to be executed.
2. Memory Address Register (MAR) – The MAR register contains the address of
the memory from which it's reading or writing.
3. Memory Data Register (MDR) – The MDR register is the actual register which
holds the data of the program.
4. Instruction Register (IR) – It’s a temporary register holding the instruction
which is just fetched.
5. Control Unit (CU) – The program instructions are decoded in this register and
stored into IR, it selects the machine resources.
6. Arithmetic and Logic Unit (ALU) – It performs the actual execution of
multiplication, division, subtraction, addition, comparison and logical
operations.
7. Floating Point Unit (FPU) – It does the Floating point operations.
Steps included in Fetch Execute Cycle –
1. Fetch Instruction – In this the next instruction of the program is fetched from the
address of memory which is stored in the program counter to the Instruction
Register. The program counter directs toward next instruction in the queue which
will be used in next cycle at the end of a fetch operation.
2. Decode the Instruction – In this the encoded code in the instruction register are
interpreted and decoded.
3. Execute – In this, the control unit of CPU passes decoded instruction as a set of
the control signal of the relevant function of the processor. Sometimes the
instruction's operation may need Arithmetic Logic Unit (ALU) to perform the tasks
so in such case the registers pass the data which are given to ALU and after the
operation is done the new value is set over the register (Ayomaonline.com,
2011).

After the steps are done the CPU reaches back to the Program Counter for any
further instructions if there are any instructions then the cycle repeats else the STOP
condition is met and the cycle terminates.

Conclusion
I have explained details of computer system architecture and its components. The
teacher will be easily able to understand about computer system architecture and can
teach students easily through this report. This report carries details about input-output
devices. Also, carry information about alphanumeric and numerical data and how it is
stored in a computer system.
In this report, different types of data conversion are explained with an example of how
decimal number convert to binary or how binary number convert to floating point value.
Also, carry description about Boolean gates and a figure is made carry different types of
gate and according to figure a truth table is generated. CISC and RISC instruction set is
also discussed. Fetch-execute cycle is also discussed in this report. This report carries
a detailed description of the computer system and its components.

References
 Bbc (2018). BBC Bitesize - KS3 Computer Science - Representing text, images and
sound - Revision 4. [online] Bbc. Available at:
https://www.bbc.co.uk/education/guides/zpfdwmn/revision/4 [Accessed 15 Jan.
2018].
 Bbc (2018). BBC Bitesize - GCSE Computer Science - Boolean logic - Revision 3.
[online]Bbc.. Available at:
https://www.bbc.co.uk/education/guides/zc4bb9q/revision/3 [Accessed 15 Jan.
2018].
 Do (2016). Boolean gates. [online] Doc. Available at:
http://www.doc.ic.ac.uk/~dfg/hardware/HardwareLecture02.pdf [Accessed 15 Jan.
2018].
 Cs (n.d.).Conversion [online] Cs. Available at:
http://www.cs.ucr.edu/~ehwang/courses/cs120a/00winter/binary.pdf [Accessed 15
Jan. 2018]
 Eehawaii, H. (n.d.). 4.1.1 The ASCII Character Set. [online] Ee.hawaii. Available at:
http://ee.hawaii.edu/~tep/EE160/Book/chap4/subsection2.1.1.1.html [Accessed 15
Jan. 2018].
 Mkhisalg (2018). Types and components of computer system. [online]
Slideshare.net. Available at: https://www.slideshare.net/mkhisalg/types-and-
components-of-computer-system [Accessed 13 Jan. 2018].
 Computer Science GCSE GURU.(2018). Von Neumann Architecture - Computer
Science GCSE GURU. [online] Available at:
https://www.computerscience.gcse.guru/theory/von-neumann-architecture
[Accessed 13 Jan. 2018].
 Agrawal, S. (2012). Computer Memory ? Different Types Of Memory In Computer
With Examples. [online] Successnotes4u.blogspot.in. Available at:
http://successnotes4u.blogspot.in/2012/02/computer-memory-different-types-of.html
[Accessed 13 Jan. 2018].

 Milosavljevic, V. (2018). Polling vs. Interrupt. [online] Electronics-base.com.
Available at: http://www.electronics-base.com/useful-info/software-related/90-polling-
vs-interrupt [Accessed 13 Jan. 2018].
 Techopedia (n.d.).What is an Address Bus? - Definition from Techopedia. [online]
Techopedia. Available at: https://www.techopedia.com/definition/292/address-bus
[Accessed 15 Jan. 2018].
 Cs.stanford (2012).RISC vs. CISC. [online] Cs.stanford. Available at:
https://cs.stanford.edu/people/eroberts/courses/soco/projects/risc/risccisc/
[Accessed 15 Jan. 2018].
 Bbc.co.uk. (2018). BBC Bitesize - GCSE Computer Science - Instructions - Revision
5. [online] Available at: https://www.bbc.co.uk/education/guides/z2342hv/revision/5
[Accessed 15 Jan. 2018].
 Ayomaonline.com. (2011). Fetch-execute cycle and impact of operation types.
[online] Available at: http://www.ayomaonline.com/academic/fetch-execute-cycle/
[Accessed 15 Jan. 2018].