ACSC 155
System Analysis and Design
5. Input/Output Design
Dr. Stephania Loizidou Himona
1
 Input/Output Design
 User Interfaces
Dr. Stephania Loizidou Himona
2
Data Entry Methods and Devices
 Keyboard
– (QWERTY)
– Ergonomic
– Touch-sensitive
– Musical
 Mouse
Dr. Stephania Loizidou Himona
3
Keyless Data Entry
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OCR (optical character reader)
OMR (optical mark reader)
MICR (magnetic ink character reader)
Barcode readers
Pen Input
Scanners
Graphics Tablet
Microphones
Dr. Stephania Loizidou Himona
4
Output Methods and Devices
 Screens
 Printers
 Speakers
Dr. Stephania Loizidou Himona
5
Graphical User Interfaces (GUIs)
 A method of user communication with an
operating system. Basically, to give
commands.
 By selecting icons, buttons, bars or boxes.
 Quick and easy to learn.
 Promote standardisation of application
program interfaces.
 Reduce errors.
Dr. Stephania Loizidou Himona
6
System User Issues for Input Design
 Volume of input should be minimised
– Enter only variable data, do not enter constant data
– Do not input data that can be calculated or stored in
computer programs
– Use codes for appropriate attributes
 Source documents should be easy for
system users to complete
– Include instructions for completing the form
– Minimise the amount of handwriting
Dr. Stephania Loizidou Himona
7
 Design documents so that they can be easily
and quickly entered into the system
– Data to be entered should be sequenced
– Portions of the form that are not to be input are
placed in or about the lower right portion of the
source document
Dr. Stephania Loizidou Himona
8
System User Issues for Output
Design
 Computer outputs should be simple to read
and interpret
 The timing of computer outputs is important
 The distribution of computer outputs must
be sufficient to assist all relevant system
users
 The computer outputs must be acceptable
to the system users who will receive them
Dr. Stephania Loizidou Himona
9
Internal Controls for Inputs and
Outputs
 The number of inputs should be monitored
 Care must also be taken to ensure that the data is
valid
 The timing and volume of each output must be
precisely specified
 The distribution of all outputs must be specified
 Access controls are used to control accessibility of
video (on-line) outputs
 Control totals should be incorporated into all
reports
Dr. Stephania Loizidou Himona
10
 ISAM – Indexed sequential access method
– For storing data records on a physical storage
device in sequential order for sequential
processing
– Allows direct access to the particular record
 Batch mode versus On-line processing
 Methods of interacting with a system
- command language
- menu
- form
- object
- natural language
Dr. Stephania Loizidou Himona
11
Fourth-generation language
 Extremely sophisticated languages
 Little or no professional programming skills
 Categories (7):
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Query languages
Report generators
Graphics languages
Application generators
Very high-level programming languages
Application software packages
Microcomputer tools
Dr. Stephania Loizidou Himona
12
Testing and Debugging
 Testing
– Black box testing
– White box testing
– Alpha and Beta testing
– Selection of test data
Dr. Stephania Loizidou Himona
13
 Debugging (Errors or bugs)
– Translator diagnostics
– Cross-referencing, Traces, Variable dumps
– Dry runs
– Splitting the program
– Test strategies
Dr. Stephania Loizidou Himona
14
Installation - Integration
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Parallel running
Pilot running
Big bang, or direct change
Phasing
Dr. Stephania Loizidou Himona
15
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System Analysis and Design SUBJECT CODE: ACSC 155