[TUHS] advent of "modern" Unix OS

[John Cowan via TUHS]

On Sat, Apr 25, 2026 at 12:51 PM Larry McVoy via TUHS <tuhs at tuhs.org> wrote:

> On Sat, Apr 25, 2026 at 04:32:35PM +0000, Andrew Lynch via TUHS wrote:
>
> > HiI've been watching the conversation on the various Unix and Unix-like operating systems and began to wonder.?? Is there such thing as an era of "modern" Unix OS?????

"Modern" is a slippery adjective. Its meaning depends on who you are,
where you are, and what you are doing, and can almost never be pinned
down to a specific era.  Modern times began around 1800 in Europe and
North America, later elsewhere; modern art begins around 1863 in
France, later elsewhere.  And so on.


> Mojo did the VM system that gave us the
> first version of mmap() (that I'm aware of, maybe Multics had one?).

In Multics it was all mmap(); there was no concept of I/O as we know
it. You opened a segment either on some file or on anonymous paged
memory, just like today. If you needed a file bigger than 256K 36-bit
words, you had to do things differently; eventually multi-segment
files got a specialized I/O library.  And the Multics shell was called
that because it was literally a skeleton that mmaped your programs
into its own memory (but using multi-ring hardware protection).

TOPS-20 also had mmap() under the name of PMAP alongside conventional I/O.