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DR FlexOS? (Miscellaneous)

posted by diasan(R), 07.03.2013, 22:48

> Hi, I just stumbled at some information about something called FlexOS.

A few years ago (ending in1997) I worked for an equipment manufacturer which
made use of FlexOS in its products. So I have had experience in using it, and
programming for it.

> What I can make out is that it was a successor to DR Concurrent DOS.
Sort of - certainly some of the drivers and headers had references to CDOS.

> It was a multiuser
Yup. I never used the equivalent of setuid() / setgid() on in (it had both groups and users),
but the documentation seemed to imply that one needed to be 'root' userid to make either call.

We always used it as the 'root' like userid in the shipping product.

> (? - at least it had a login facility)
Which was optional, if not used the one would simply execute the start up config file as 'root'.

> /multitasking OS that was
> first "published" (there has to be a better term) somewhere around 1986
> (judging by the manuals) for 80286 based PCs.
The 286 version was the main one we used, though we also used the '386 version in development.
However, despite the 386 version having better MMU handling, we were never able to switch to it
for product as we still had 286 based shipped devices to support.

The 386 version could run COFF executables. Both the 286 and 286 versions supported forms of
shared libraries. The 386 version could run all 286 programs.

> It was basically DOS-like.
External - at the command.286 shell level it was.

Internally, it was quite different.

I've seen it described as being a bit VMS like in how most system APIs were available in asynchronous as well as synchronous forms. It sort of seemed like an interesting blend of VMS, unix, and DOS.

Programming abstractions included things like PIPEs and Shared Memory.

> It used the same commands with some additions (not unlike OS/2 or Windows NT),
> but also provided some facilities like command piping, stderr redirection
> and similar.


> It supported multiple "windows", something a sort of like Unix virtual
> consoles, so you could run several full screen tasks along each other.

That was an optional installed program, more like the unix 'layers' scheme in that it
multiplexed the physical console across a number of virtual console.

> It came with GUI: X/GEM - a multitasking version of DR GEM;
An optional separately licensed piece (we did not have it), but the video (VGA, CGA) drivers were
scattered with bit of support for graphics modes. We always used it in text mode.

> and networking: supporting ethernet and arcnet.
Let's see - it has NetBIOS (over TCP), NetBEUI, and SMB support.
SMB came in two forms - one compatible with an early PC LAN version, and their own native
FlexNET form which was a cleaner version supporting their native filesystem APIs (together with
resource sharing: PIPE, FILE, DISK, DEVICES).

> It seems it could run CP/M and DOS
> executables from different architectures: 68xx CP/M, DOS x86, CP/M86, M/PM
> (from what I could make out, not completely sure).
Yes. It could run a subset of DOS programs, as it only provided a limited set of compatibility,
the 386 version having more support (V86 mode) but still a bit limited. We used to run
TurboC under it (as an alternate to the supplied MetaWare High C). Some DOS editors
could be run under it.

This was provided by a set of replaceable 'Front Ends'. Actually, I believe the 68xxx version
is available (as binaries) on the website where the old free'ed DR files may be found. e.g. it
is one of the pieces lumped in with the collection of old CP/M variants.

> As I see in Wikipedia, it was used mostly in industrial applications and
> was also used in some Siemens solutions.
Yup - ours was a quasi industrial use - Petrol Station Forecourt control systems,

> Does anyone know what happened with FlexOS and why did it fail (if it did)?
Novell bought DR, and supported it.
The ISI bought it, and eventually seemed to let it rot (I changed employers around that time).
The Wind River bought it (or ISI?) and killed it.

I don't know that it failed as such, it was just aimed at an embedded control market.
I know we started to look for replacements after Novell began to lose interest.

> Was it ever offered as an OS for PCs or was limited only to industrial
> applications?
Well the 286 and 386 versions ran on PCs. We used them a development and test machines
(self hosted development).

> The list of features is impressive for the time (1986).

Yeah quite nice, a 32 bit programming model despite running on 16 bit machines.
(Albeit segmented on the 80286). I've been tempted to re-implement a version of it
for private hacking. But in the last 15 years still haven't got around to it.

The native file system was also interesting. It was FAT (8.3) with extensions, supporting stuff
like pre-allocation of files, case sensitive names, slightly better globbing than on DOS, access
permissions (Read, Write, Execute, Delete) for World, Group, Owner

Actually, I think I've also seen PDF files containing scans of the various manual (including
programmers manual) online.


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