Computing History


The objective of this discussion is to introduce the Therac-25 case, explain what happened in this historical event, discuss the ethical responsibilities of such individuals and organizations and at the end provide my viewpoint about this historical event.


The way as the software becomes more complex and usable, this is very common that scientists introduce the use of software to the medicine. Between June 1985 and January 1987 disasters occurred with a system named the Therac-25, which was a computerized radiation therapy machine. In the related period, six known accidents occurred with massive overdoses applied to the patients (Leveson & Turner, 1993).

As stated by the Leveson & Turner, 1993, the Therac-25 software was developed by only one person, using the assembly language, and it took many years to be completed. However, there wasn’t much documentation.

The technical aspect of the Therac-25 failure is that that software controlled by the operator if the operator used to trigger the buttons of the controller board slowly, the machine would operate fine, because while the development of the Therac-25 machine it was tested with slow command inputs. However the operators of this machines after operating thousands and thousands of patients became familiar with the controller board, they got used to the machine and used to type very and very faster, what used to trigger the bug, and the bug started to send massive radiations over the patients. (Udacity – Software testing Course, 2017).

In my viewpoint, it is more of a software testing failure, but of course, as software testing is part of software engineering, it needs to be considered an engineering failure.


In spite of having to know that software developed in the seventies and to do not have been properly tested, is a big failure in the procedures of the development of the critical health machine. But a machine of such complexity in my viewpoint, to be developed by a single person without documentation is also a big mistake by the company who created it. Unfortunately, the software engineering methods and studies we have today weren’t available at that time.

Just by the factor of the software to have minimal or none documentation puts all the responsibility to the developer: How can we build something we don’t know how it works since assembly code is very close to the machine code and all the other equipment were handled by this single software? How could understand the error codes provided by the software since there is no documentation?

If the error code showed that the problem was related to the operating timing while using the control board, the software could be easily repaired and the machine could continue to be used and to save lives.


Since technology is under development and it is not certainly free of problems and mistakes. According to the mistake evidenced in this documentation, in my opinion, it is not a case of cyberethics nor computer ethics, but a concern of professional ethics. I purely believe that because the operators of the Therac-25 had to be in a constant training environment of the use of such machines. Since the first case, that should be evidenced what was the mistake happened, what was the cause of that and why should we continue operating such machine since the first people who died because of the mistake which happened.


Spite of an engineering mistake mixed to an operative mistake, the development of software engineering and the advances of the medicine has, of course, much to improve the social quality of life in terms of the health. I consider many mistakes may have caused the Therac-25 case, but of course evicted. Spite of all the factors, it can be considered a software engineering failure, since the program was waiting for the perfect use of the software, the software had no documentation and the problems could not be fixed since it had no feedback of what was going on and could not help in the fix of such problem.


N.G. Leveson, C. T., 1993. An investigation of the Therac-25 accidents. IEEE Computer Society, 26(7), pp.18-41.

Udacity, 2017. YouTube. [Video Online] Available at: [Accessed 27 August 2017].

Today I am here to share with you something very interesting about what happened in the ’70s when the code was shared by hobbyists which used to develop software in the universities.

I just knew this after watching the movie Revolution OS (which is very nice indeed), and the purpose of this post is to show you who was the “enterprising” mind behind corporate software: Bill Gates — and I just don’t want to make the idea I am against him, of course not, since I believe he did a lot for computer science and Microsoft looks like is changing their minds to open source software since cloud computing took the scene.

There it follows the e-mail Bill Gates sent to the hobbyists encouraging them to make money with software and closing codes/patents — whatever:


p.s:  A very interesting movie to watch is the Revolution OS — a movie about Linux, which tells a bit about Linux, GNU the all the Open Source Software and initiatives. You can find it on


The main point to be covered in this discussion is the Target Corporation security breach that took place in 2013, which affected customers who swiped their credit and debit cards between Nov. 27/2013 and Dec. 15/2013, and became a very important topic in network security. This security issue was announced via a report written by the security researcher Brian Krebs, who published that Target had suffered a data breach and the customer’s card information was totally exposed and unsecured in 2013 (CNN Money, 2013).

About the Company

Target Corporation is the 2nd largest American retailing company having revenue of $72,596 in 2013 and taking the 29th place in the ranking on Fortune’s World Most Admired Companies List (Target Corporation, 2014).

Affected and Impacted Customers

The main fact is that in 2013 about 40 million credit and debit card information stored in the Target Corporation computers, was stolen by hackers and this information was used by bad-intentioned users, who possibly would use this information for self-benefit.

Technical Information and Causes

To understand a bit more about it, security experts said that hackers targeted the point-of-sale system, maybe infecting those computers with malware in the terminals or possibly collecting the data on route to the credit card processors (CNN Money, 2013).

Specialists said that the main problem is the obsolete technology used in American Credit and Debit card transactions. Comparing to the technology used abroad credit cards have a chip that creates a unique PIN for the transaction and is also more difficult to clone, different from the technology used in the USA, which the magnetic strip could be easily duplicated.

My personal critical thoughts

With my experience on developing software, first, a big mistake is probably the technique of storing the complete user’s credit card information since it is not necessary because there is the possibility of storing only a part of the credit card number and ask the user to fill it when necessary, so I would never encourage storing all the card information at any computing resource.

Based on my findings I can conclude that the main reason all the information being stolen is the use of obsolete technology not only in Target Corporation but also by all the American companies that use credit card related operations.


Computer security cannot be guaranteed with the kind of technology we have nowadays especially when we considering networks, which data can be intercepted and you do not have control to where this is information is being transferred and stored.

The Target Corporation case became very popular on the news, but this kind of security breach occurs frequently on the Internet and so much information is stolen every day, nevertheless, it is possibly never come to the news.


CNN Money. 2013. Target: 40 million credit cards compromised. [ONLINE] Available at: [Accessed 03 August 14].

Target Corporation. 2014. Corporate Overview. [ONLINE] Available at: [Accessed 03 August 14].

CNN Money. 2013. Target credit card hack: What you need to know. [ONLINE] Available at: [Accessed 03 August 14].

Think Progress. 2013. Why Target’s Security Breach Was Bound To Happen. [ONLINE] Available at: [Accessed 03 August 14].