From: jerry@connection.prospect.com (Jerry Shekhel)
Subject: Re: Amiga 4000/Atari Falcon
Organization: Molecular Simulations, Inc.
Date: Wed, 2 Sep 1992 15:10:23 GMT
X-Posted-From: connection.prospect.com
X-Posted-Through: sol.ctr.columbia.edu

1992Aug31.064154.3811@desire.wright.edu> fheitkamp@desire.wright.edu writes:
>>
>> and other such "last resorts".  Do you actually think that VM was invented
>> for DOS?  Yes, accessing disk is slower than accessing RAM chips, but it's
>
>	The first VM implementation that I'm aware of is VMS on VAX. 
>	I have never researched the history of VM.  Perhaps you have.
>	Care to share?
>

Nah.  My only point here was that VM was certainly *not* invented to extend
the limitations of MS-DOS.

>> 
>> You are dangerously uninformed here.  Software memory access protocols
>> such as XMS (extended) and EMS (expanded) have nothing to do with Intel's
>> segmented addressing; they have to do with the 8086 only having 20 address
>
>	Why I'm I dangerously uniformed? And where did I say EMS and XMS
>	had anything to do with segmented memory?
>

In the article to which I replied, you said something to the effect of, "There
are so many kludges for fixing Intel's segmented memory -- EMS, XMS, VM, etc."

>
>	I think just about 
>	anybody with an objective viewpoint would agree to at least
>	XMS and EMS being kludges.
>

No.  As much as I don't like using these in my programs, the *only* way to
use more than 1MB RAM on an 8086 (or any x86 in Real Mode) is via a software
interface such as XMS or EMS.  I would call something a "kludge" if there were
a better way of achieving the same goal.  In this case, there isn't.

>
>	Segmented memory is another story.
>	Intel sells it as a form of memory protection.  But since Intel has
>	decided that Motorola and Digital were correct enough  that they 
>	implemented a flat memory model in their latest processors...
>

In the 8086 (and Real Mode), segmentation was used only to increase the
address space to 1MB without extending the registers beyond 16 bits.  In
Protected Mode, however, segmentation serves several additional purposes --
a means of protection and address virtualization.  On the 386, Intel did
not implement "flat" addressing; memory access is still segmented.  They
just lifted the segment size limit.  I think it was a great solution; one
can use one big segment as if it were a flat address space, or continue to
use segmentation for the advandages it provides.

>
>Jerry,  what does Polygen do?  Just curious.
>

Molecular Simulations, Inc. (was Polygen, merged with MSI in Sunnyvale) is
a developer of high-end molecular modeling applications such as QUANTA and
CHARMm.  Our software runs on graphics workstations manufactured by SGI, IBM,
and HP.
--
+-------------------+-----------------------+--------------------------------+
| Jerry J. Shekhel  | Molecular Simulations | Time just fades the pages      |
| Drummers do it... | Inc.  Waltham, MA USA | in my book of memories.        |
|    ... In rhythm! |     (617) 890-2888    |              -- Guns N' Roses  |
+-------------------+-----------------------+--------------------------------+
|           ...! [ princeton mit-eddie bu sunne ] !polygen!jerry             |
|                            jerry@polygen.com                               |
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