[TUHS] DEC OSes (was: MS-DOS)

Johnny Billquist bqt at update.uu.se
Sat Jul 2 00:37:14 AEST 2016

On 2016-07-01 15:43, William Cheswick <ches at cheswick.com> wrote:
>>> >>​...​why didn't they have a more capable kernel than MS-DOS?
> ​>I don't think they cared. or felt it was needed at the time (I disagreed then and still do).
> MS-DOS was a better choice at the time than Unix. It had to fit on floppies, and was very simple.
> “Unix is a system administrations nightmare” — dmr
> Actually, MS-DOS was a runtime system, not an operating system, despite the last two letters of its name.
> This is a term of art lost to antiquity.

Strangely enough, the definition I have of a runtime system is very 
different than yours. Languages had/have runtime systems. Some 
environments had runtime systems, but they have a somewhat different 
scope than what MS-DOS is.
I'd call MS-DOS a program loader and a file system.

> Run time systems offered a minimum of features: a loader, a file system, a crappy, built-in shell,
> I/O for keyboards, tape, screens, crude memory management, etc. No multiuser, no network stacks, no separate processes (mostly). DEC had several (RT11, RSTS, RSX) and the line is perhaps a little fuzzy: they were getting operating-ish.

Uh? RSX and RSTS/E are full fledged operating systems with multiuser 
proteciton, time sharing, virtual memory, and all bells and whistles you 
could ever ask for... Including networking... DECnet was born on RSX.

And RSTS/E offered several runtime systems, it had an RT-11 runtime 
system, an RSX runtime system, you also had a TECO runtime system, and 
the BASIC+ runtime system, and you could have others. You could 
definitely have had a Unix runtime system in RSTS/E as well, but I don't 
know if anyone ever wrote one.

In RSX, compilers/languages have runtime systems, which you linked with 
your object files for that language, in order to get a complete runnable 


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