Transcript CSC 150 UNGRADED QUIZ - Concordia University Wisconsin

HUMAN-COMPUTER
INTERACTION II
A. INPUT UNITS.
B. OUTPUT ACTIVITIES
(Prepares for lab on Wednesday).
A. INPUT UNITS (H/W).
 (1) What is the purpose of input units?
 (2) How does character translation work?
 (3) What are the types of input unit?
1. What is the purpose of input
units?
 To translate real-world data (in a humanly
understandable form) into “computerese”
(binary).
 E.g. from last time: keyboard. We enter
characters, but computer only understands
binary, so keyboard translates characters
into binary sequences.
 But how?
2. How is a character translated
into binary?
 Each character is assigned a numeric code
using a coding scheme. 2 common schemes
are:
 ASCII
 EBCDIC
 For part of the ASCII Table, see Figure 4.3,
p. 128 in An Invitation to Computer
Science.
How are characters stored?
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Each character is stored in a “byte.”
A byte is a sequence of 8 bits.
A bit = a binary digit.
How many distinct characters can be
represented with 1 byte?
3. Types of input unit.
 Input units can be either general purpose or
special purpose.
 A general purpose unit will accept many
formats for data e.g. a keyboard will accept
any string of characters, a “point and click”
device (such as a mouse) enables you to
select any option.
General purpose input units.
 1. Keyboards. What happens when a key is
pressed on a keyboard?
 2. Point and click devices. How do they
work?
 3. Scanners. Translation from analog to
digital.
Special purpose input units.
 1. Optical scanners. E.g. Optical character
recognition (OCR) devices such as Bar
Code Scanners, connected to point of sale
(P.O.S.) terminals.
 2. Optical mark readers (OMR’s) e.g.
Scantron.
Special purpose units continued.
 3. Magnetic input units e.g.
 Magnetic Ink Character Recognition
(MICR).
 Magnetic Strip Readers e.g. Tyme, credit
card.
New trends:
 1. Specialized devices for those who are
disabled or have impaired senses. Use nonconventional input, e.g. input by puff of air
for paralyzed people, Braille keyboard for
the blind, etc.
 2. Voice activated. May need training
period and problems e.g.?
 Illness, impersonation via recording.
B. Output Activities.
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The purpose of output.
Types of representation:
(1) Reports,
(2) Graphics,
(3) Multimedia.
The Purpose of output.
 A. Output translates the binary in RAM
into a variety of meaningful representations
(reports, graphics, multimedia).
 B. Why have different types of
representation?
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Different types of representation are suited to
for different purposes e.g. do we need detail or
trends?
Example.
 1. For an audit or criminal investigation,
you need all the data, so a detail report is
appropriate.
 2. When doing marketing or analyzing
profitability, general trends may be more
helpful e.g. as shown on a bar chart.
(1) Reports.
 Reports consist of text and numbers.
Pictures might be included, e.g. a picture of
an employee, but they are not essential
information: the data is not being graphed
by the pictures.
 Types of report: (A) documents, (B) detail
reports, (C) summary reports, (D) exception
reports.
(A) Documents.
 These are “hardcopy,” e.g. internet pages,
word processed documents, emails, FAX’s
consisting largely of text (.TXT. .DOC).
 Disadvantage: data is not organized in a
 simple, visual format.
(B) Detail Reports.
 These typically show numeric and text
fields from a data file organized under
column headings e.g. Student ID, GPA.
 In a detail report, for every line of data,
there is one report line. E.G. a detailed sales
report.
 Advantages and disadvantages?
(C) Summary Reports.
 These show totals, averages, overall trends
e.g. not each individual car sale, but how
each model has been doing in total / on
average. Individual records are not shown,
 otherwise we cannot “see the forest for the
trees.”
(D) Exception Reports.
 These show only unusual data e.g. poorly
paid baseball players, honest politicians,
government workers etc.
 More seriously, they can be used to log
patients with unusual symptoms or invalid
entries in a data file.
(2) Graphics.
 Show data in a visual format with text only
as explanatory labels.
 Types of graphic include:
 A. Line graphs,
 B. Bar charts,
 C. Pie charts.
A. Line graphs.
 1. Very useful for direct comparisons of a
few variables e.g. comparing leading brands
for sales.
 2. Like a detail report, shows all individual
data points, but in a visual way.
B. Bar charts.
 1. Relate quantitative variables to
qualitative variables e.g. Sales
(quantitative), Department (Qualitative).
 2. Similar to a summary report: shows
totals, not individual data points.
C. Pie charts.
 1. Show the relation of parts to a whole.
 2. Good for proportions, percentages.
 3. Also summarizes data, but in a different
way.
(3) Multimedia.
 Trend in education to incorporate text,
graphics (including stills, animation and
video) and sound in one interactive package
e.g. Computer Concepts CD.
 E.g. PowerPoint, educational aids, games on
CD-ROM or laser disks.
 Advantages and disadvantages?