We need to discuss something that you will not see discussed in any other book about software development--what happens when two users work together?
The first mass-produced computers were called PCs, personal computers. The wording kind of gives it away--they were personal devices. When this term was first used, it was meant to distinguish them from the big mainframes that could have dozens of users at the same time. However, each job on the big machines was running for one user only, so there was little a user would note about the other users, besides a drop in performance.
The PC was not so different. The user has the machine to themselves, but since all work done on the mainframe was also ...
