USING GAMES IN THE TEACHING OF DIGITAL SYSTEMS

AND OF COMPUTERS ARCHITECTURE

Pedro José Guerra de Araújo

IT - Institute of Telecommunications, Department of Computer Science, University of Beira Interior

Av. Marquês d’Àvila e Bolama 1, 6200 Covilhã, Portugal

João Vieira Baptista

IESIG – Instituto de Estudos Superiores Isidoro da Graça, São Vicente, Cabo Verde

Keywords: Computer science, learning methodologies, computer games.

Abstract: This work presents a pedagogic experience regarding the use of games as support examples on Digital

Systems and Computers Architecture teaching. For this work it is not the game itself that is important, but

the technologies involved in the construction of the game. Examples of each one of these technologies are

presented here through the construction of three different versions of the same game. The first version is

totally made in hardware using digital integrated circuits, the following is accomplished by programming

using the Assembly language and finally a third version using a high-level language. The importance of

these examples lies in the fact that each one of these versions allows one to exemplify techniques that can

also be found in other types of computer programs. Besides capturing the attention and the students' interest

immediately, the games are good examples to serve as support to the concepts’ exposition done by the

teacher in the classroom.

1 INTRODUCTION

Just as it happens in other scientific areas, the

computer science teaching faces great challenges.

Nowadays, the educational system has to compete

with simplified forms of obtaining knowledge such

as magazines, television and the Internet.

The diffusion of these media and the easy access

to several equipments (PC's, pocket calculators,

game machines, mobile phones) frequently creates

the illusion in the students that it is not necessary to

dominate the theoretical knowledge that it is in the

base of the operation of those technologies.

Seemingly, what is necessary is to know how to use,

instead of knowing how to do. Another problem is

that, due to time constraints, the examples used in

the classroom are just isolated fragments of larger

programs, or they are simplified versions of more

complex digital circuits, unable to attract the

attention and the students' interest. In a simpler way,

using the Internet, the students can easily obtain

complete systems at zero cost. This creates great

challenges to the teacher on how to convince the

students about the importance of the matters that

they should learn.

The games are good examples to help to change

this situation. Indeed, in terms of computers

technology, games present important challenges.

They force the use of sophisticated programming

techniques and the interface with the hardware, often

leading to the development of new devices for data

acquisition and information visualization, as well as

new and better processing algorithms and data

structures, more efficient in terms of time and space.

This means that the development of games involves

the deep knowledge of the physical structure of the

machines and of related programming techniques.

Besides the technical knowledge, games appeal to

the imagination mainly in the phase of objectives

and rules definition, being an activity which is very

appreciated by the students.

This way, the games are excellent examples that

help the teacher to expose the subjects to the

students, in a “learning-by-doing” process.

José Guerra de Araújo P. and Vieira Baptista J. (2007).

USING GAMES IN THE TEACHING OF DIGITAL SYSTEMS AND OF COMPUTERS ARCHITECTURE.

In Proceedings of the Ninth International Conference on Enterprise Information Systems - HCI, pages 5-10

DOI: 10.5220/0002379900050010

 SciTePress

2 TEACHING METHODOLOGIES

Bormida et al., 1997, pointed four applied

methodologies on the digital logic and computers

architecture teaching: expositive, demonstrative,

interactive and practical.

In the expositive methodology, the presentation

of theory, concepts and other information is based

on multimedia hypertext making use of animations.

In the demonstrative methodology, the concepts

previously introduced are reinforced through

examples of practical implementations. A simulator

can be used, which can be controlled by the student

by setting the values of some of the input variables

and to observe the behaviour of the outputs. In the

interactive methodology the student make choices,

describe or calculate something. They therefore

imply an evaluation of the student's answers. Finally,

in the practical methodology, the student should

accomplish a project to acquire design capabilities.

Conceiving circuits and systems is generally more

difficult than understanding and analyzing them and

requires different and complementary skills.

In the expositive and demonstrative approaches,

the student might go through the subjects without

paying the necessary level of attention to assimilate

the topics presented. Instead, in the case of

interactive and practical methodologies, they are

forced to make decisions, leading to a larger

involvement in the study. The use of tests and

exercises with the aid of simulators is a good

methodology to evaluate if the knowledge was really

learned. In agreement with those authors, the use of

simpler tools is the most appropriate. As the

conclusion of their study shows, the students

generally prefer the experimental practice instead of

reading hypertextual material or watching simple

animation.

The development of games is an excellent

process to put into practice each of these

methodologies. As a matter of fact it is possible to

use games for to exemplify most of the techniques

involved in the development of many other types of

computer programs. Besides the hardware, these

techniques include the study and the control of

input/output devices, of the interaction between the

software and the hardware, of the organization of the

central processing units, of the memory

management, of the algorithms and data structures,

of the graphics programming, etc.

In the next chapters a small game is used to

explain these ideas.

3 THE SUM/SUBTRACTION

GAME (SSG)

This game has two main objectives, the first is the

construction of the game itself and the second is its

use. From the construction’s point of view, the game

exemplifies each one of the methodologies presented

in the previous paragraphs. It helps the teacher in the

exhibition of the concepts concerning digital logic

and simultaneously allows the concepts’

demonstration. Afterwards the students are invited to

accomplish the game in a simulator to test its

operation and to correct some mistakes. Next, they

should implement the circuit using several

technologies.

From the point of view of its use, the game

intends to be an auxiliary to the students' training in

binary arithmetic. Namely, it allows the practice of

conversions from binary to decimal and from

decimal to binary, but also the training of the

arithmetic operations sum and subtraction using the

two's complement notation. To win the game, the

player must be able to quickly do these calculations

and conversions.

Figure 1 show the components of the game,

which rules are:

• After the "Start" button is pressed, the circuit

generates an hexadecimal random value in the

range from - Fh (-15) to Fh(15), that is shown

in the "Number" display;

• Since that moment, the player has a short

interval of time to introduce in "Binary Value"

input the value in binary code corresponding to

the symmetric of the "Number" value

(including the sign bit); the length of time to

introduce the answer is controlled by the

"Speed" selector;

• After pressing the "Test" button the circuit adds

the values in "Number" and in "Binary Value"

("Number" + "Binary Value"), and then:

¾ if the value of the sum is zero (correct

answer) the circuit marks a point in "Ok"

in favour of the player and also increases

the total number of attempts in "Total";

¾ if the value of the sum is not zero (wrong

answer), or if the time to answer was

elapsed without player's answer, only the

total number of attempts in "Total" is

increased;

• The difference between the "Total” value and

the "Ok" value indicates the number of wrong

answers.

ICEIS 2007 - International Conference on Enterprise Information Systems

Figure 1: Components of SSG (Sum/Subtraction Game).

From now on the construction of the game will

allow one to exemplify almost all of the concepts

related with the operation of a personal computer, at

hardware and software levels. It also serves to show

the implementation of a same idea using different

technologies. For that, the game will be initially

implemented in hardware, using integrated circuits,

followed by an implementation in machine language

and finally, using a high-level language. In the next

paragraphs the contributions of these different

implementations of the game on computer

technologies’ teaching will be discussed.

3.1 Learning Digital Systems

One of the most common techniques used on the

teaching of digital systems is the use of simulators,

that there are several examples (Ferreira et al.,

2003). They allow the modelling of digital circuits

as logic gates, counters, registers and memory, and

also reproduce real systems such as elevators, traffic

lights or the doors and windows of a house. By using

them it is possible to develop small and medium size

projects such as elevators controllers, traffic lights

management systems or residential alarm systems.

The example of the game here presented was

built using the simulator Digital Works (WWW1,

2006). Although being a quite simple simulator, it

allows modelling most of the concepts presented in

an introductory course to digital systems. The

schematic diagram of the circuit is presented in

figure 2, while figure 3 shows the picture of the

correspondent hardware implementation.

By analyzing the circuit it can be seen that

although the game’s objective is very simple, it uses

most of the digital components found in more

complex systems. The components used by the game

are, among others, logic gates, counters, registers,

memory, input/output devices (switches, leds and

seven-segments displays), decoders, multiplexes,

arithmetic circuits (sum/subtraction), comparators,

clock generator and frequency dividers. The interest

of the game comes from the fact that with only one

circuit the operation of all these components can be

explained.

3.2 Learning Computer Architecture

Another important subject is the teaching of the

Assembly language. For that, several simulators

exist (Ferreira et al., 2003). Once acquired the

essential concepts on digital circuits, the students

should understand how these circuits are

interconnected to form larger blocks, such as central

processing units (CPU), memory controllers,

communication channels (buses), input/output ports

and finally a complete personal computer (PC).

They should also understand that those blocks

dialogue between them using a low-level language

formed by groups of binary digits, called machine

language.

The knowledge and the practice of this language

allow the students to understand the data flows that

circulate inside the machine as well as the way they

are processed. By this way, the students consolidate

their knowledge about circuits’ operation which

allows them to develop techniques for programs’

optimization.

The programming of the SSG game in Assembly

language was made using the NASM Assembler

(WWW2, 2006). The program makes use of

concepts such as dialogue with the operating system

and the input/output system (calls to the OS and of

the BIOS), routines for generation of random

numbers, low-level manipulation of the keyboard, of

the mouse and of the video, graphics programming,

etc. Figure 4 presents the screen of the game.

Binar

Value

Start S

eed

slow

fas

Test

Ela

sed Time

Number OK Total

USING GAMES IN THE TEACHING OF DIGITAL SYSTEMS AND OF COMPUTERS ARCHITECTURE

Figure 2: Schematic Diagram of SSG.

Figure 3: The hardware of SSG.

ICEIS 2007 - International Conference on Enterprise Information Systems

Figure 4: SSG done in Assembly (NASM).

3.3 Learning High-level Languages

Most of the first year students of an engineering

course are already familiarized with some high-level

programming language, like C or Pascal. But for

many of them the relationship between the

instructions of these languages and its execution by

the hardware is unknown, even mysterious.

After the two previous versions of the game have

been accomplished (in hardware and in machine

language), the students have a better idea about that

relationship. Namely, they already understand how

the software controls the hardware.

The next step is to understand that the high-level

languages are closer to the human languages and at

that they provide a set of enlarged capacities

including better control and data structures, much

more efficient instructions and improved error

handling. Besides, they hide from the programmer

the complex details of the operating systems as well

as the details of the hardware.

The programming of the SSG game in a high-

level language was made in Object Pascal using the

integrated development environment (IDE) Delphi

from Borland/Inprise (WWW3, 2006). The program

allows exemplifying the drawing of user interfaces,

through the use of visual components as buttons and

dialogue boxes, but it also exemplifies the use of

special components as timers. Figure 5 presents the

screen of the game.

4 CONCLUSIONS

Games constitute an excellent way to teach hardware

and software technologies. The construction of a

game involves the use of several techniques, such as

the control of hardware for data acquisition, as well

as the use of several data processing algorithms and

of information visualization.

They allow the capture of the students' interest

on the concepts required in its accomplishment.

Firstly, the development of the original idea and the

definition of the rules of the game. Secondly, the

study of models and algorithms to be used (could

include mathematics and physics knowledge up to

now without apparent usefulness). Thirdly, the

development phase of hardware and/or software and

finally the user interface.

The creation of games is a task that motivates the

students, easing the understanding of the concepts

transmitted by the teacher in the classroom. They

stimulate the students' imagination, making them

propose new improvements and new functionalities.

The games are also incentives in professional terms,

because the students know that they constitute

important business opportunities.

USING GAMES IN THE TEACHING OF DIGITAL SYSTEMS AND OF COMPUTERS ARCHITECTURE

Figure 5: SSG done in Borland DELPHI.

REFERENCES

Bormida, G. D., Ponta, D., and Donzellini, G., 1997.

Methodologies and tools for learning digital

electronics. IEEE Transaction in Education, 40(4).

Ferreira R., Chieppe U., Freitas G., Biancardi C., 2003.

Software Livre no Ensino de Sistemas Digitais e

Arquitectura de Computadores, Universidade Federal

de Viçosa, Departamento de Ciência da Computação.

WWW1 (2006). Digital Works,

http://www.spsu.edu/cs/faculty/bbrown/circuits/

WWW2 (2006). NASM, The Netwide Assembler,

http://sourceforge.net/projects/nasm/

WWW3 (2006). Delphi IDE, http://www.borland.com/

us/products/delphi/index.html

ICEIS 2007 - International Conference on Enterprise Information Systems