UNIVERSITY OF SOUTH AFRICA
College of Science, Engineering and Technology — School of Computing
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
INF1520: Human-Computer Interaction
Assignment 4 | Semester 2, 2026
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
INF1520
Module Code:
Human-Computer Interaction
Module Name:
Assignment 4: Questions 1–10
Essay Topic:
Assignment 4
Assignment Number:
INF1520/102/0/2026
Reference:
Submitted in partial fulfilment of the requirements for
INF1520: Human-Computer Interaction, UNISA 2026
,UNISA | INF1520 Human-Computer Interaction — Assignment 4
Question 1: The Four Eras of Computing Devices and HCI
[8]
The development of computing devices and of human-computer interaction as a discipline
is generally traced through four broad eras, each defined by a shift in the dominant hardware,
the style of interaction it permitted, and the kind of user it assumed.
1.1 The Mainframe / Batch-Processing Era
The earliest era of computing was dominated by large, room-sized mainframe computers op-
erated exclusively by trained specialists. Interaction was indirect: programs were submitted
as batches, typically on punched cards or paper tape, and results were only available after
the batch had been processed, often hours or days later (Dix, Finlay, Abowd and Beale, 2004).
There was no concept of a dialogue between user and machine; the "user" was effectively the
computer operator, and ordinary people had no direct contact with the system at all. Comput-
ers in this era were treated purely as calculating tools, not as communication partners.
1.2 The Command-Line / Time-Sharing Era
The invention of time-sharing operating systems allowed several users to interact with a
single mainframe or minicomputer through terminals, giving the impression of a dedicated,
conversational session. Interaction shifted to typed textual commands entered at a com-
mand line, with the system responding immediately rather than after a batch delay. This era
introduced the first real notion of a human-computer dialogue, but it still demanded that users
memorise exact command syntax, which restricted effective use to programmers and other
technically trained users (Preece, Rogers and Sharp, 2015).
1.3 The Graphical User Interface (GUI) / Personal Computing Era
The introduction of the personal computer, together with the WIMP paradigm (windows,
icons, menus, and pointers) pioneered at Xerox PARC and popularised by Apple and Mi-
crosoft, marked the third era. Direct manipulation replaced typed commands: users could
point, click, and drag visual representations of files and applications (Shneiderman, Plaisant,
Cohen, Jacobs and Elmqvist, 2016). Because the interface visualised the available options,
Page 2 of 18
, UNISA | INF1520 Human-Computer Interaction — Assignment 4
computers became usable by non-specialists for the first time, and HCI emerged as a formal
field of study concerned with making these graphical systems learnable and efficient.
1.4 The Web, Mobile, and Ubiquitous Computing Era
The current era is characterised by internet connectivity, mobile and touch-based devices, and
computing embedded in everyday objects (wearables, smart appliances, voice assistants).
Interaction is no longer confined to a desk; it is mobile, multimodal (touch, voice, gesture),
and often social, and it must accommodate a hugely diverse range of screen sizes, contexts
of use, and user populations (Shneiderman et al., 2016). HCI in this era focuses on context-
awareness, accessibility, and designing for continuous, embedded interaction rather than a
single seated session at a desktop machine.
Page 3 of 18
College of Science, Engineering and Technology — School of Computing
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
INF1520: Human-Computer Interaction
Assignment 4 | Semester 2, 2026
⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄ ⋄⋄
INF1520
Module Code:
Human-Computer Interaction
Module Name:
Assignment 4: Questions 1–10
Essay Topic:
Assignment 4
Assignment Number:
INF1520/102/0/2026
Reference:
Submitted in partial fulfilment of the requirements for
INF1520: Human-Computer Interaction, UNISA 2026
,UNISA | INF1520 Human-Computer Interaction — Assignment 4
Question 1: The Four Eras of Computing Devices and HCI
[8]
The development of computing devices and of human-computer interaction as a discipline
is generally traced through four broad eras, each defined by a shift in the dominant hardware,
the style of interaction it permitted, and the kind of user it assumed.
1.1 The Mainframe / Batch-Processing Era
The earliest era of computing was dominated by large, room-sized mainframe computers op-
erated exclusively by trained specialists. Interaction was indirect: programs were submitted
as batches, typically on punched cards or paper tape, and results were only available after
the batch had been processed, often hours or days later (Dix, Finlay, Abowd and Beale, 2004).
There was no concept of a dialogue between user and machine; the "user" was effectively the
computer operator, and ordinary people had no direct contact with the system at all. Comput-
ers in this era were treated purely as calculating tools, not as communication partners.
1.2 The Command-Line / Time-Sharing Era
The invention of time-sharing operating systems allowed several users to interact with a
single mainframe or minicomputer through terminals, giving the impression of a dedicated,
conversational session. Interaction shifted to typed textual commands entered at a com-
mand line, with the system responding immediately rather than after a batch delay. This era
introduced the first real notion of a human-computer dialogue, but it still demanded that users
memorise exact command syntax, which restricted effective use to programmers and other
technically trained users (Preece, Rogers and Sharp, 2015).
1.3 The Graphical User Interface (GUI) / Personal Computing Era
The introduction of the personal computer, together with the WIMP paradigm (windows,
icons, menus, and pointers) pioneered at Xerox PARC and popularised by Apple and Mi-
crosoft, marked the third era. Direct manipulation replaced typed commands: users could
point, click, and drag visual representations of files and applications (Shneiderman, Plaisant,
Cohen, Jacobs and Elmqvist, 2016). Because the interface visualised the available options,
Page 2 of 18
, UNISA | INF1520 Human-Computer Interaction — Assignment 4
computers became usable by non-specialists for the first time, and HCI emerged as a formal
field of study concerned with making these graphical systems learnable and efficient.
1.4 The Web, Mobile, and Ubiquitous Computing Era
The current era is characterised by internet connectivity, mobile and touch-based devices, and
computing embedded in everyday objects (wearables, smart appliances, voice assistants).
Interaction is no longer confined to a desk; it is mobile, multimodal (touch, voice, gesture),
and often social, and it must accommodate a hugely diverse range of screen sizes, contexts
of use, and user populations (Shneiderman et al., 2016). HCI in this era focuses on context-
awareness, accessibility, and designing for continuous, embedded interaction rather than a
single seated session at a desktop machine.
Page 3 of 18
