Reading 05 Response
From the reading, the Therac-25 is a radiation therapy device that treats patients with either a beam of electrons or x-rays. The previous versions of this device had many manual controls to allow for a technician to set everything up with their hands, but the Therac-25 switched to software control in favor of hardware. The software had been the same since the first version of the Therac, so it was considered "battle tested" and did not need to be revised, but it turned out the switch to software dependance created some problems that were initially unreproducible when operation of the machine is done by hand. The determined problems with the Therac software were a race condition in the code which would not catch a switch in modes from x-ray to electron and a variable which determines whether the hardware is configured correctly had a byte overflow which caused the variable to display that there was no error when there in fact was. The reason for these trivial errors in such...