HCI Assignment

1. Jeddie Bere
HCI Assignment 1
Describe any 4 interaction devices in detail and explain the developments that occurred
on these devices over the years. What does the future hold for them?
1. A keyboard- Is a typewriter-style keyboard which uses an arrangement of buttons or keys
to act as mechanical levers or electronic switches. Following the decline of punch cards and
paper type, interaction via tele-printer style became the main input device for computers.
Despite the developments of alternative input devices such as the mouse, touch screen pen,
character recognition and voice recognition. The keyboard remains the most commonly
used and most versatile device used for direct human input into computers.
There are 2 types of keyboards namely,
a) MECHANICAL KEYSWITCH KEYBOARDS
This type uses an individual switch for each key. Pressing a key creates a connection
between 2 signal lines from the keyboard controller. When a connection is made the
keyboard controller sends a signal to the computer with information about the type of key
selected.
b)CAPACITATIVE
A keyboard will have 2 sheets of semi-conductive material separated by a thin sheet of
Mylar .When a key is pressed the plunger presses the 2 sheets of semi-conductive material
together , changing the total capacitance of the 2 sheets. The keyboard controller can tell
the key selected by the amount of capacitance.
A keyboard typically has characters engraved or printed on the keys and each press of keys
typically corresponds to a single written symbol. Most keyboard keys produce letters,
numbers or signs, other keys or simultaneous key presses can produce actions or computer
commands. In normal usage a keyboard is used to type text and number into word
processor, text editor or other programs. In a modern computer, the interpretation of key
presses is generally the left to the right software. Keyboards are the only way to enter
commands on a commandlineinterface.
The history of the keyboard –while typewriters are the definite ancestor of all key-based text
entry devices, the computer keyboard as a device for electromechanical data entry and
communication derives largely from the utility of two devices, tele-printers and keypunches.
It was through such devices that the modern computer keyboard inherited their layouts. In
1870s the keyboard on the tele-printer played a strong role in point to point and point to
multipoint communication while the keyboard on the keypunch device played a strong role
in data entry and storage.
The keyboard remained primarily, most integrated computer peripheral well into personal
computing until the introduction of a mouse as a consumer device in 1984. By this time text
exclusive user interfaces with sparse graphics gave way to comparatively graphics rich icons
on screen. However the keyboard remain control to human computer interaction to the

2. present , as even mobile personal computing devices such as smart phones and tablets
adapt the keyboard as an optional virtual touch screen based means of data entry.
Spectacular improvements have been developed for this device, a standard requirement for
all PCs, since it has first appeared.With all kind of embedded functions, but essentially
nothing has changed, at least up until now. However, things might take a different turn, with
the extraordinary wireless keyboardconceptdevelopedbythecompanyOptimus.
2. Monitor or display-is an electronic visual display for computers. Monitor comprises the
display device circuitry and an enclosure. The display device in modern monitors is typically
a thin film transistor liquid crystal display, while older monitors use a cathode ray tube about
as deep as the size screen size. Originally, computer monitors were used for data processing
while television receivers were used for entertainment. From 1980 onwards, computers and
their monitors have been used for both data processing and entertainment while television
has implemented some computer functionality.
The history of monitors- the first monitors used was cathode ray tubes. Until early 1980s,
they were known as video display terminal and were physically attached to the computer
and keyboard. The monitors were monochrome, flickered and the image quality was poor.
1981 IBM introduced the Colour Graphic Adapter which could display four colours. In 1984
Enhanced Graphics Adapter was introduced which was capable of producing 16million
colours and had a resolution of 640 by 350. CRT remained the standard for computer
monitors through the 1990s. CRT technology remained dominant in the personal computer
monitor market into the new millennium partly because it was cheaper to produce and
offered viewing angles close to 180 degrees.
The future vision is to create light weight, portable display surfaces that can be instantly
updated and are used for everything from videos to foldable computer screens to wall
paper. A research on paper-like displays focuses on investigating new materials and
manufacturing costs.
3. The mouse –is a pointing device that functions by detecting two dimensional motions
relative to its supporting surface. Physically, a mouse consists of an object held under one of
the user’s hands, with one or more buttons.
The mouse sometimes features other elements, such as "wheels", which allow the user to
perform various system-dependent operations, or extra buttons or features that can add
more control or dimensional input. The mouse's motion typically translates into the motion
of a pointer on a display, which allows for fine control of a graphical user interface
Computer mice began to appear in the early 1980s but many computers require an
additional expansion board or card to use them during this period of history. Many mice
were beige or white. In late 1980s a greater variety of IBM compatible computers began to
be sold with a serial port built in and Apple Macintosh system were among the first to be
sold with a mouse included. Most mice had either one or two buttons. Software was
generally designed so that it could be used with or without a pointing device. A disadvantage

3. of serial computer mouse is that they must be plugged when other serial accessories are
utilised on computers which have only one port of this type.
In early 1990s one mice button had become relatively cheap. Microsoft offered a bundled
mouse and windows 3.1 package, because of the significant advantage it provides in using
windows. Mice with scroll wheels or USB cables have become more wide spread. A greater
number of computers now have dark coloured exteriors and mice with similar coloration
have been provided to match them. In 1999, Apple dropped the use of ADB mouse ports and
replaced them with USB.
Overally, the history of the computer mice has frequently involved different ports, more
buttons and a trend in favour of including them with new systems. It remains to be seen
whether the mouse will continue to undergo such changes during the next ten years or
twenty years or if it will stay much the same. Mice might become obsolete, at least as far as
the mainstream segment is concerned. The main reason for this situation is the appearance
and rapid developments of touch screen technology and touch pads, which enable users to
carry out the same functions as the ones previously enabled by the mice.
4. Light pen – a light pen is an input device that is used with a cathode ray tube display to
point at items on the screen or to draw new items or modify existing ones. The light pen had
a photo sensor at the tip that responds to the peak illumination that occurs when the CRT
scanning spot passes its point of focus.
The display system correlated the timing of the pulse from the photo sensor with the item
being displayed to determine the position of the light pen. A light pen can work with any CRT
based display but not with LCD display. The light pen is used to draw items with the aid of a
tracking cross. As the light pen is moved across the screen, the part of the tracking cross
sensed changes thus allowing the direction of movement of the light pen to be ascertained.
The tracking cross can be redrawn to locate it at the expected new centre of the light pen’s
position and thus appears to follow the light pen. The user brings the pen button to make
contact.
The light pen is fairly easy to implement. The light pen works by sensing the sudden small
change in brightness of a point on the screen when the electron gun refreshes that spot. By
noting exactly where the scanning has reached at that moment, the X, Y position of the pen
can be resolved. This is usually achieved by the light pen causing an interrupt, at which point
the scan position can be read from a special register or computed from a counter or timer.
The pen position is updated on every refresh of the screen.
The history of the light pen- light pen became moderately popular during the early 1980s. It
was notable for its use in the Fair light Computer Music Instrument (CMI) was the first
polyphonic digital sampling synthesiser. It was designed in 1979 by the founders of Fairlight,

4. Peter Vogel and Kim Ryrie and based on a dual microprocessor computer designed by tony
Furse in Sydney, Australia.The first light pen was created around 1952 as part of the
Whirlwind Project.
While most people do majority of their writing on computers these days, there is still a huge
market for pens especially innovative ones. These creative innovations go a way beyond the
colourful pen or sparkly gel writers. There is a whole new genre of digital pens, for example,
that look like they will play significant roles in future. They allow people to write on any
surface, eliminating the need to destroy as the pen records motions digitally storing them
for future uploads on computers.