[onre]

"Another change since the original OSes were initially being built is the need for security"

I do not know what's referred to as "original OSes" but many old operating systems had actually pretty decent security architecture. MULTICS and VMS, for example, and many others too.

[thecombjelly]

It's true that some did. I was more referring to the history of most of the major OSes we use today and specifically when it came to the first microcomputers. Generally when they were first being used (and the OS was being expanded) security was not much of a concern.