Richard:
Where can I find more info on OpenVMS?
Thanks
__________________________________________
Ranga Nathan / CSG
Systems Programmer - Specialist; Technical Services;
BAX Global Inc. Irvine-California
Tel: 714-442-7591 Fax: 714-442-2840
Richard Troth <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port <LINUX-390@VM.MARIST.EDU>
02/07/2005 09:11 AM
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Re: comparison beetwen Linux and UNIX
Andri ...
You've gotten some good responses. Does this information help?
Linux is a done-by-volunteers implementation of POSIX.
Unix is a branded implementation of POSIX (and contains "DNA",
as they call it, of the historical Unix operating system).
As far as we know, Linux does not contain any AT&T Unix code.
Unix (POSIX) implementations that run on mainframe hardware include:
+ UTS (originally from Amdahl, now spun off to UTSGlobal)
- AIX/370 (including both S/370 and XA operation modes)
- AIX/ESA .. way ahead of its time!
- "experimental" systems such as IX/370 and VM/IX
* USS
* OpenVM
+ Linux
The last two, marked with "*", are not stand alone operating systems.
The two marked with "+" are the only currently viable POSIX
operating systems available for mainframe hardware.
UTS is the system on which I learned Unix. It has always
exploited S/370 (and now S/390 and zSeries) hardware, not merely
tolerating it. For example, UTS treats 3270 terminals as
normal terminals and addresses the EBCDIC matter and the block mode
nature of these devices in some creative ways. I have heard it said
that the original developers of UTS not only understood mainframe
hardware but also understood Unix. (This is counter to the usual
"us -vs- them" embattlement between mainframe people and Unix people.)
AIX/ESA deserves mention for its academic and historical value.
It had a Mach based kernel, a feature which makes it superior to Linux.
It exploited S/390 "data spaces" rendering enormous memory regions,
beyond its contemporary Unix peers.
AIX/370 was sold commercially. (My experience was in academia.)
It was a port of AIX for PC hardware to the S/390, and to me seemed
a bit half-hearted: did not exploit S/390 hardare, toleration only.
USS (UNIX Systems Services) is a POSIX layer on top of MVS.
The character set is EBCDIC, which any traditional Unix user
will find very confusing. Other than that, USS is Unix
in that it follows the POSIX specification and has Unix branding,
so legally it is as close to Unix as HP-UX or AIX, though it is
not what a Solaris customer would expect.
OpenVM is a POSIX layer on top of CMS. Here too, the character
set is EBCDIC. I am a huge fan of OpenVM (since getting over the
char set issue). It is an execellent implementation, but it
does lack some important features (notably, fork() is partial).
If someone who knows IX/370 or VM/IX could share their knowledge
we might learn a little more about the fork() situation along the way.
-- R;
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