types of software systems and their attributes Flashcards
paper 2
types of software
open source
bespoke
off-the-shelf
open source software
software whose source code is visible and can be modified by users
typically license terms promote collaboration and allows sharing for free
open source pros
usually free
if you can program, you can customise to your own needs
open source cons
no right to support it bugs exist
may not have as powerful features as paid for software
bespoke software
software that has been written to order for a specific client
bespoke pros
software can be customised to client’s exact needs
unique software provides unique competitive edge
bespoke cons
can be very expensive
software not immediately available - must be designed etc
off-the-shelf software
general purpose software typically purchased from a retailer
off-the-shelf pros
cheap
readily available on demand
lots of support should exist
off-the-shelf cons
may not solve the problem exactly as you wanted
users tend to pay for features they end up not using
what is a safety critical system
a system in which failure could result in injury or death
fail passive
may fail but has backup measures in place
eg autopilot fails then pilot takes control
fault tolerant systems
can continue to operate on an interim basis but with limited capacity
eg having a redundant system in place split into sections so if one section fails they can activate the redundant system temporarily
fail-safe systems
has manual overrides in place for if failure occurs - eg have a time delay and a warning that allows for human interaction before they become critical
eg medical devices
what is a control system
type of computer system that manages, commands and directs other devices/systems
can be used for:
safety
working remotely
precision
examples of control systems
traffic lights - uses sensors or set amount of time to changes
heating systems - temp sensors taking readings and turns on heating to alter temp
name 3 types of sensors
temperature
humidity
infra-red
smoke
sound
pressure
touch
safety related (critical) system features
redundancy - all components have backup features
expense - high costs due to extremely thorough testing
specialised - highly skilled workers to develop systems and specialised hardware custom-made for their purpose
expert system
a piece of software that uses AI to model the knowledge of a human expert
consists of:
knowledge base
inference engine
user interface
knowledge base
detailed database which contains enough data to allow the expert system to come to an educated conclusion
inference engine
consists of a set of rules which determines what question the user will be asked next based on the answers the user has provided thus far + based on searching the knowledge base.
user interface
presents the questions and feedback to the user and accepts input from the user
must be user friendly to avoid incorrect inputs
expert system uses (examples)
medical diagnosis
playing strategy games
expert system pros
available 24/7
no concern about bias
no travel costs
can be used as a training tool
doesn’t go on holiday
expert system cons
no common sense so can return ridiculous results
high initial costs
can promote digital divide as not everyone has relevant access
facts
facts/rules should be produced by a specialist with relevant expertise
results must be clearly understandable to user
list outputs in order of suitability or indicate a relative score
should explain its reasoning for reaching its decisions so accuracy can be evaluated
internet
worldwide interconnection of computers and networking hardware
intranet
network that is local to an organisation
can only be accessed by members
search engine
piece of software that allows a user to search for web pages and other docs
can search a website, an intranet or the whole internet
use web crawlers to scour all pages identifying key words in search
content is transmitted back to search engine and stored in an index to be presented
ranking (search engines)
search engines look through their index for highly relevant content and orders the content by relevance to searcher’s query
robotics
something in the physical world that is controlled by a computing system using sensors and actuators
robotics pros
can do dangerous jobs for humans
cheaper for manufacturing + can do repetitive jobs + output consistent (no mistakes)
can work 24/7
tech in weather forecasting
collecting quantitative numerical (eg rainfall, temp) data using sensors
predictions made based on current conditions + calculations performed on data to see how it will change over time
done by powerful computers with parallel/distributed processing to ensure calculations done quickly
what is computer aided design/manufacturing (CAD?CAM)
the process designing a product on a computer, testing it using simulations and then manufacturing thousands of copies in a factory
