[comp.sys.ibm.pc.hardware] 386SX and EMS 4.0

ted@helios.ucsc.edu (Ted Cantrall) (09/29/90)

I am in the midst of the agony of trying to decide which SX board to buy.
I know I want a Chips & Tech chip set and AMI BIOS, but one of the options
is a board that has EMS 4.0 built in. Does this seem like a good idea?
Might it be faster or less likely to crash? Would it even be of any use?
Thanks in advance for your collective help.		-ted-


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mlord@bwdls58.bnr.ca (Mark Lord) (09/29/90)

In article <7297@darkstar.ucsc.edu> ted@helios.ucsc.edu (Ted Cantrall) writes:
>I am in the midst of the agony of trying to decide which SX board to buy.
>I know I want a Chips & Tech chip set and AMI BIOS, but one of the options
>is a board that has EMS 4.0 built in. Does this seem like a good idea?

Don't fuss over the EMS capability.  It is great for 286's, but with a 386
(sx/dx.. who cares) the EMS capability is much better when provided by
software such as QEMM or 386^MAX.  With hardware EMS, you are usually stuck
with the supplied drivers, which do not approach the capabilities of these
two software packages.

In summary, with a 386 system, built-in EMS 4.0 is not something you
should demand or require of the motherboard.  Ignore it and look at the
other features instead, such as memory capacity, good construction, 
good built-in bios setup program, etc..  And plan on buying QEMM or 386^MAX.
-- 
 ___Mark S. Lord__________________________________________
| ..uunet!bnrgate!mlord%bmerh724 | Climb Free Or Die (NH) |
| MLORD@BNR.CA   Ottawa, Ontario | Personal views only.   |
|________________________________|________________________|

reisert@ricks.enet.dec.com (Jim Reisert) (10/20/90)

In article <4460@bwdls58.UUCP>, mlord@bwdls58.bnr.ca (Mark Lord) writes...
> 
>Don't fuss over the EMS capability.  It is great for 286's, but with a 386
>(sx/dx.. who cares) the EMS capability is much better when provided by
>software such as QEMM or 386^MAX.

I disagree.  I have a need to be able to load programs into high RAM, but
not under the guise of protected mode.  The way to do this would be with the
C&T chipset, which has built-in EMS 4.0 capability, rather than QEMM.  Alas,
I don't have this capability, and am stuck with poor performance running
heavy-duty coprocessor operations.

It pays to consider all the options.

jim

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"The opinions expressed here in no way represent the views of Digital
 Equipment Corporation."

James J. Reisert                Internet: reisert@ricks.enet.dec.com
Digital Equipment Corp.         UUCP:     ...decwrl!ricks.enet!reisert
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draper@cpsin2.cps.msu.edu (Patrick J Draper) (10/21/90)

In article <16508@shlump.nac.dec.com> reisert@ricks.enet.dec.com (Jim Reisert) writes:
>
>In article <4460@bwdls58.UUCP>, mlord@bwdls58.bnr.ca (Mark Lord) writes...
>> 
>
>I disagree.  I have a need to be able to load programs into high RAM, but
>not under the guise of protected mode.  The way to do this would be with the
>C&T chipset, which has built-in EMS 4.0 capability, rather than QEMM.  Alas,
>I don't have this capability, and am stuck with poor performance running
>heavy-duty coprocessor operations.
>
>It pays to consider all the options.
>
>jim
>
>=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>
>"The opinions expressed here in no way represent the views of Digital
> Equipment Corporation."
>
>James J. Reisert                Internet: reisert@ricks.enet.dec.com
>Digital Equipment Corp.         UUCP:     ...decwrl!ricks.enet!reisert
>77 Reed Road
>Hudson, MA  01749-2895

I thought that all access to EMS was through the protected mode, and
that even if you had a C&T chipset it didn't change things. The
C&t Chipset simply eliminates the need for an EMS board. Also I believe
that the software emulation of EMS on a 386 machine is faster than using
the C&T chipset because the 386 can switch between real and protected
mode very quickly compared to a 286. 

Patrick Draper  -----   Michigan State University

kdq@demott.COM (Kevin D. Quitt) (10/21/90)

In article <16508@shlump.nac.dec.com> reisert@ricks.enet.dec.com (Jim Reisert) writes:
> I have a need to be able to load programs into high RAM, but
>not under the guise of protected mode.

    386MAX has a utility called 386LOAD which will load programs into
high DOS memory, without 386MAX's protected mode being invoked.  It just
requires that there be RAM up there.

-- 
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Kevin D. Quitt         demott!kdq   kdq@demott.com
DeMott Electronics Co. 14707 Keswick St.   Van Nuys, CA 91405-1266
VOICE (818) 988-4975   FAX (818) 997-1190  MODEM (818) 997-4496 PEP last

                96.37% of all statistics are made up.

james@bigtex.cactus.org (James Van Artsdalen) (10/22/90)

In <1990Oct20.204053.20116@msuinfo.cl.msu.edu>, draper@cpsin2.cps.msu.edu
	(Patrick J Draper) wrote:

> I thought that all access to EMS was through the protected mode, and
> that even if you had a C&T chipset it didn't change things.

Not true.  EMS has nothing to do with protected mode.  QEMM & 386^max
kludge EMS support by using the pager in the 386.

> Also I believe that the software emulation of EMS on a 386 machine is
> faster than using the C&T chipset because the 386 can switch between
> real and protected mode very quickly compared to a 286.

But that's not the whole story.  When in virtual 86 mode, the 386 runs
slower than in real mode (not all operations).  So even if QEMM were
somewhat faster than the C&T code, the system overall is slower.

In addition, QEMM and such things have serious compatibility problems.
You're always better off with hardware support if you have it because
(1) it's net faster and (2) it's more compatible and less like to
cause the floppy drive to fail or something.
-- 
James R. Van Artsdalen          james@bigtex.cactus.org   "Live Free or Die"
Dell Computer Co    9505 Arboretum Blvd Austin TX 78759         512-338-8789

phil@brahms.amd.com (Phil Ngai) (10/23/90)

In article <48848@bigtex.cactus.org> james@bigtex.cactus.org (James Van Artsdalen) writes:
|In <1990Oct20.204053.20116@msuinfo.cl.msu.edu>, draper@cpsin2.cps.msu.edu
|	(Patrick J Draper) wrote:
|
|> I thought that all access to EMS was through the protected mode, and
|> that even if you had a C&T chipset it didn't change things.
|
|Not true.  EMS has nothing to do with protected mode.  QEMM & 386^max

As a matter of fact, EMS was invented for the 8088, which doesn't
even have a protected mode.

|kludge EMS support by using the pager in the 386.

I wouldn't call it a kludge. I would call the incomplete implementations
offered by C&T and the like a kludge.

|> Also I believe that the software emulation of EMS on a 386 machine is
|> faster than using the C&T chipset because the 386 can switch between
|> real and protected mode very quickly compared to a 286.

C&T implements EMS in hardware so there is no issue with the time
it takes to switch from real to protected mode.

|In addition, QEMM and such things have serious compatibility problems.

Actually, it is C&T that has serious compatibility problems with
things like DESQVIEW.

|You're always better off with hardware support if you have it because
|(1) it's net faster and (2) it's more compatible and less like to
|cause the floppy drive to fail or something.

If you're saying a 286 with C&T is better than a 386 with QEMM or
386Max, I disagree.

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