W#08-Computer System Reliability Computer System Reliability depends on hardware, software, and users. As computer scientists, we must design safe hardware that can be given commands by software that executes intentional action. We must be careful in the specification of our intent, since it is the behavior for which we alone are accountable. Many guidelines for ethical conduct in professional fields includes various statements of the rule: "First, Do No Harm." When we undertake the design of sophisticated computer-base medical systems we must understand the risks involved and design our systems to reduce those risks to the level of insignificance. This requires fail-safe systems for hardware, software, operators and patients. We must understand and control the behavior of all components. Our behavior as designers, developers, implementers, and users must be as near perfection as humanly possible. To approach perfection, we must be accurate observers, with the ability to explain all of the behaviors produced by a system and understand their implications. Unfortunately, human behavior always fails at some level of system design, development, implementation, use and maintenance. We can become the deciding factor in system success if we do not recognize our intrinsic imperfections, biases, motivations, goals and limitations. Depending on the consequences of system failure, we must exercise appropriate care, accuracy, and safety. Read the Therac-25 article contained in the Resource Section titled Reliability and Excellence. While reading, identify and categorize the behaviors of the creators, marketers, users and (unfortunately) victims of the Therac-25 computer controlled radiation therapy system. Each actor's behaviors establishes moral culpability. For instance, the decision to eliminate physical safety interlock systems and substitute software safety systems is ultimately an ethical decision that has profound moral consequences. After identifying all actors (programmers, designers, engineers, doctors, users, etc.) and behaviors, organize the identified behaviors into categories on the basis of the actors. Submit this itemization in a concise organized listing to be used to complete your final project of evaluating these behaviors by the computer science and software engineering code of ethics. This listing constitutes completion of W#08. Briefly introduce the system and its characteristics and problems, then present the listing of actors and behaviors concisely as a description of what was done and the subsequent material consequences. For example, management did not develop written software engineering standards and thus it was impossible to determine the evolutionary process that produced the Therac-25 software. Prepare your assignment using any word processor with grammar and spell-checking capability. Conciseness, focus and specificity in your response should be foremost in your writing. Limit the length of your response to no more than 500 words. You may use selected text from the article to facilitate your listing of events but indicate this material by either double quotes are indention. Submit your individual essay as a single uploaded rich text file, .doc or docx. Do not submit as PDF or exotic file types that are unreadable by Microsoft Word. Consult the Standards for Written Work contained in the Resources section of TRACS for this class.