You have to keep in mind this was a different time. There were no Free unixlike operating systems with full source code available, and no immensely powerful PCs

You have to keep in mind this was a different time. There were no Free unixlike operating systems with full source code available, and no immensely powerful PCs to run them on. There was no world wide web with every bit of information available. There were few practical ways of learning how computers worked except by breaking into them and studying them.