The document discusses the importance of increasing reliability and safety in software and hardware development to avoid errors and system failures. It emphasizes that reliability and safety are distinct but interrelated concepts, often conflicting in complex systems, and outlines various causes of computer failures such as poor design, inadequate testing, and user errors. Solutions to enhance reliability and safety, as well as the risks associated with over-dependence on computers, are also examined.

1. INCREASING RELIABILITY AND SAFETY

2. BACKGROUND
Nowadays, increasing reliability and safety were very important in hardware and software development
to avoid errors. Reliability is the degree to which and assessment tool produces stable and consistent
result.
Safety is being protected from harm or other non-desirable outcomes. Roughly about increasing reliability
and safety is more about software that can perform their task consistently and safe from any harm that can
bring error in the software.

3. REASONS OF COMPUTER FAILURE
A- The job they are doing is naturally difficult
• At the beginning computer were made for simple daily
task like mathematical computation, providing straight
answer.
• Now the computer systems interact with the real world
(both machinery and unpredictable humans) and include
complex communications networks, numerous features
and interconnected subsystems and large ones.
B- The job is done poorly
This is happening from the system design and
implementation to the management and use.

4. INCREASING RELIABILITY AND SAFETY
is more about
SOFTWARE
That can
PERFORM THEIR TASK CONSISTENTLY
and...
SAFE FROM ANY HARM
that can bring error to the software.

5. BY INCREASING
RELIABILITY AND SAFETY
either in hardware or software
development it will
AVOID ERROR
issues to occur.

6. Safety vs. Reliability :
• Safety and reliability are NOT the same
— Sometimes increasing one can even decrease the other.
— Making all the components highly reliable will have no impact on system accidents.
• For relatively simple, electro-mechanical systems with primarily component failure accidents,
reliability engineering can increase safety
• For complex systems, need something more liar

8. Safety and reliability are DIFFERENT PROPERTIES
which may be supporting or conflicting.
Increasing the reliability of a safety function can make an ENTIRE SYSTEM SAFER.
The distinction is clearest if we may imagine NON-
SAFETY ways in which a system must be reliable.

9. For example:
An airplane needs to be available to fly.
It could be quite safe if it never took off, but that wouldn't be
considered reliable.
Alternatively, It could reliably transport passengers from place to place,
but kill one or two every flight. That would be reliable but not safe.

10. CAUSES AND IMPACTS:
CAUSES:
• Insufficient testing and debugging
• Poor safety design
• Software error
• Inadequate reporting and investigating of
accidents

11. System design and development:
 Inadequate attention to potential safety risks
 Interaction with physical devices that do not work as expected
 Incompatibility of software and hardware or of application software and the operating system.
 Reuse of software from another system without adequate checking
 Overconfidence in software
 Carelessness
 Management and use
 Data-Entry errors
 Inadequate training of users
 Errors in interpreting results or output
 Failure to keep information in databases up to date
 Overconfidence in software by users
 Insufficient planning for failures, no backup systems or procedures

12. IMPACTS
• System may contain some
error that been overlooked
• Design error lead to injury or death
• System failure occurs.
• Risk and problem of the system will not been identified by the
developers.

13. SOLUTION:
1.0perator cannot restart machine without re-entering information
2.ensuring that metal platies in place if x-ray beam is selected
3. Error messages will be made clearer
4. Dose administered clearly shown to operator
5. Limiting editing keys to limit any accidental type ins
6. All manuals rewritten to reflect new changes

14. CONCLUSION
 We are too dependent on computers
 We are exposing ourselves to tremendous risk
and dangers
 There is a real need to develop more proficient
systems that will make software more reliable
and flawless