14 Oct
2005
14 Oct
'05
6:28 p.m.
Subject: Re: Releasing OS/2
From: "Chuck Guzis" <cclist at sydex.com>
Date: Fri, 14 Oct 2005 15:37:43 -0700
To: cctalk at classiccmp.org
On 10/14/2005 at 5:11 PM Allison wrote:
One approach. I ran a multiprocessor Z80 system back in '81-82 with one
difference idle processors (or processors idling) could take on tasks
While 1+ing the question we can add 8bit
multitasking for Z80 other than
MP/M to look at.
Molecular was running MT software simply by using a CPU card for each user. from the system exec.
That Durango system (that I'm STILL trying to give away) was designed from
the ground up with MT in mind. Since the 8085 can't do dynamic address
relocation very easily, we simply put the MT facilities in the compiled (to
a sort of P-code) BASIC. File access control and data sharing was a part
of it. Except for the very lowest level system utilities, all programs
were written in it. A 5 MHz 8085 could support 5 users quite comfortably.
Added memory was 1K pages, mapped through 64x9 bipolar RAM.
I've done a memory paged 8085 system, interesting.
I have to ask, how does all of this fit with the question?:
How does OS/2 warp V3 compare to other PC OSs like CDR Concurrnet386 or
win3.1?
Allison
14 Oct
14 Oct
7:55 p.m.
On 10/14/2005 at 9:28 PM Allison wrote:
I have to ask, how does all of this fit with the
question?:
You asked about Z80 MT outside of MP/M. I pointed out that there's more
than one way to skin a cat. In particular, MT does not have to be an
integral feature of the OS itself.
In particular, for any system to make optimum use of MT, applications have
to be designed with MT in mind. That lets out most of the Z80
off-the-shelf apps and also goes a long way toward explaining why MP/M was
so miserable.
Cheers,
Chuck
15 Oct
15 Oct
1:15 a.m.
New subject: OS/2 vs Win3.1
Allison wrote:
How does OS/2 warp V3 compare to other PC OSs like
CDR Concurrnet386 or
win3.1?
I don't know anything about Concurrent386, but comparing OS/2 Warp with
win 3.1 is like comparing pigs with streetlights.
Win3.1 is a graphical shell around DOS. To overcome DOS' memory
limitations is uses some more advanced techniques of the processor, such
as protected mode. However, win3.1 programs are 16-bit. Win3.1 itself is
16 bit. Win 3.1 only allows cooperative multitasking. That means that a
another program can only get control if the running program gives it up.
This is a very short summery of Win3.1
OS/2 2.0 and higher are 32-bit operating systems. However, compatibility
with older OS/2 applications was considered very important and therefore
parts of the kernel and all device drivers are mainly 16 bit. Only
recently some 32-bit device drivers were written.
OS/2 has its own graphical subsystem - a very advanced one. It can run
DOS programs in 'virtual dos machines' or VDM. A special mode of the 386
processor allows a task to act as if it where a real mode task. Anything
that task does can trap the processor and thus can be handled by
exception handlers. OS/2 is very strong is this area.
OS/2 has its own file system with some special features like "extended
attributes".
OS/2 has dynamic priorities for tasks, that makes it more responsive.
For example, a task that has focus in the GUI is slightly raised in
priority. Or when a background task was blocking for something it might
receive a slight priority boost when that something becomes available.
OS/2's time critical priority is handled "soft realtime". I've used OS/2
in the past for process control, dosing in particular. For such
applications realtime behaviour is very important as a lattency of 1 sec
or more is disasterous for the product being manufactered.
I can go on and on, but if you want to know more let me know and I write
it down later on.
Regards,
Bert
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ajp166＠bellatlantic.net -
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cclist＠sydex.com