[comp.sys.ibm.pc.hardware] extended memory

kap@eng.cam.ac.uk (Kevin A.Price) (12/05/90)

Hi netlanders,

does anyone know of a solution to the following problem....

We have a 286 PC/AT with 640k conventional memory and 384k
extended memory which is located at address 1 Megabyte.

Our networking software takes up about 110k of conventional.
Also, other TSRs and device drivers use about 120k. What
we would like to do is to increase the amount of 'useable'
DOS memory. Is it possible to load some of the TSRs and
device drivers in the extended memory a la LastByte? We
do NOT have the C&T chipset though!

Any ideas will be gratefully received.

Thanks in advance.

Kev
e-mail kap@eng.cam.ac.uk

dlow@hpspcoi.HP.COM (Danny Low) (12/08/90)

>(Kevin A.Price) 
>We have a 286 PC/AT with 640k conventional memory and 384k
>extended memory which is located at address 1 Megabyte.

This does not sound quite right. It looks like you have 1MB of 
convention memory divided into the usual 640K of available
and 384K of reserved memory and not 640K of conventional and 384K of
extended memory. I do not believe you can add extended memory
in anything less than 512KB chunks. The 384KB in the 640KB to
1MB address range is reserved but is still part of the conventional memory
space. Because much of it is not in actual use, it is possible
to "high load" TSRs and drivers into this area. Because this
memory is still conventional memory, nothing special is
really needed other knowing what slots are not used. Try QRAM or Move'EM.
They are designed to do this with 286 machine with or without the
C&T NEAT chipset.

			   Danny Low
    "Question Authority and the Authorities will question You"
	   Valley of Hearts Delight, Silicon Valley
     HP CPCD   dlow%hpspcoi@hplabs.hp.com   ...!hplabs!hpspcoi!dlow 

brandis@inf.ethz.ch (Marc Brandis) (12/10/90)

In article <15090024@hpspcoi.HP.COM> dlow@hpspcoi.HP.COM (Danny Low) writes:
>>(Kevin A.Price) 
>>We have a 286 PC/AT with 640k conventional memory and 384k
>>extended memory which is located at address 1 Megabyte.
>
>This does not sound quite right. It looks like you have 1MB of 
>convention memory divided into the usual 640K of available
>and 384K of reserved memory and not 640K of conventional and 384K of
>extended memory. I do not believe you can add extended memory
>in anything less than 512KB chunks. The 384KB in the 640KB to

There are some machines that allow you to configure 1 MB as 640K of conventional
and 384K of extended RAM. All Olivetti machines (and therefore many AT&T and
some XEROX PCs) that I know can do this. Note that some remapping hardware
is required anyway, otherwise you would not be able to implement the shadowing
feature correctly. At boot time, references to the segment at F000 have to
be directed to the ROM, while they have to be directed to the RAM once the
contents have been copied.


Marc-Michael Brandis
Computer Systems Laboratory, ETH-Zentrum (Swiss Federal Institute of Technology)
CH-8092 Zurich, Switzerland
email: brandis@inf.ethz.ch

poffen@sj.ate.slb.com (Russ Poffenberger) (12/11/90)

In article <15090024@hpspcoi.HP.COM> dlow@hpspcoi.HP.COM (Danny Low) writes:
>>(Kevin A.Price) 
>>We have a 286 PC/AT with 640k conventional memory and 384k
>>extended memory which is located at address 1 Megabyte.
>
>This does not sound quite right. It looks like you have 1MB of 
>convention memory divided into the usual 640K of available
>and 384K of reserved memory and not 640K of conventional and 384K of

As a matter of fact, this could be right. I used to have a 286 clone that did
this using split memory addressing. They have some intelligence in the address
decoding that allowed the 384K to reside at the 1M mark, and be used as
extended memory.

Russ Poffenberger               DOMAIN: poffen@sj.ate.slb.com
Schlumberger Technologies       UUCP:   {uunet,decwrl,amdahl}!sjsca4!poffen
1601 Technology Drive		CIS:	72401,276
San Jose, Ca. 95110             (408)437-5254

david@csource.oz.au (david nugent) (12/17/90)

In article <15090024@hpspcoi.HP.COM> dlow@hpspcoi.HP.COM (Danny Low) writes:

>>(Kevin A.Price) 
>>We have a 286 PC/AT with 640k conventional memory and 384k
>>extended memory which is located at address 1 Megabyte.
>
>This does not sound quite right. It looks like you have 1MB of 
>convention memory divided into the usual 640K of available
>and 384K of reserved memory and not 640K of conventional and 384K of
>extended memory.

Eh?  The "usual" in most AT machines with 1 meg is that the upper 384K
starts at the 1 meg mark, NOT occupying so-called "reserved" areas.

I've only seen one AT/286 - a Compaq some time back - which mapped it's
memory otherwise (some technical reasons why, but in any case the RAM was
still not "available" for use by applications or device drivers).


> I do not believe you can add extended memory
> in anything less than 512KB chunks.

Sure you can.  9 x 64K RAM chips in one - many extended
memory boards can take them.


> The 384KB in the 640KB to 1MB address range is reserved but 
> is still part of the conventional memory space. Because much of 
> it is not in actual use, it is possible to "high load" TSRs 
> and drivers into this area.

Oh dear.  Where do I start?  :-)

No, it's not possible to load TSR's and device drivers into this
so-called "conventional" memory, with the exception of using the
extra 64K available via the A20 line at the 1 meg boundary....


> Try QRAM or Move'EM. They are designed to do this with 286 
> machine with or without the C&T NEAT chipset.

UNLESS - you have the C&T NEAT chipset or a true LIMS 4.x memory card,
using QRAM and Move'Em.  But then, we're not discussing "extended"
memory then, but "expanded" memory, which is an entirely different
thing.

-- 
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sophist@brainiac.raidernet.com (sophist) (12/20/90)

david@csource.oz.au (david nugent) writes:

> In article <15090024@hpspcoi.HP.COM> dlow@hpspcoi.HP.COM (Danny Low) writes:
> 
> >>(Kevin A.Price) 
> >>We have a 286 PC/AT with 640k conventional memory and 384k
> >>extended memory which is located at address 1 Megabyte.
> >
> >This does not sound quite right. It looks like you have 1MB of 
> >convention memory divided into the usual 640K of available
> >and 384K of reserved memory and not 640K of conventional and 384K of
> >extended memory.
> 
> Eh?  The "usual" in most AT machines with 1 meg is that the upper 384K
> starts at the 1 meg mark, NOT occupying so-called "reserved" areas.
> 
> I've only seen one AT/286 - a Compaq some time back - which mapped it's
> memory otherwise (some technical reasons why, but in any case the RAM was
> still not "available" for use by applications or device drivers).
>[stuff deleted
> > The 384KB in the 640KB to 1MB address range is reserved but 
> > is still part of the conventional memory space. Because much of 
> > it is not in actual use, it is possible to "high load" TSRs 
> > and drivers into this area.
> 
> Oh dear.  Where do I start?  :-)
> 
> No, it's not possible to load TSR's and device drivers into this
> so-called "conventional" memory, with the exception of using the
> extra 64K available via the A20 line at the 1 meg boundary....
>[sruff deleted]
>         Fidonet: 3:632/348   SIGnet: 28:4100/1  Imex: 90:833/387
>               Data:  +61-3-885-7864   Voice: +61-3-826-6711
>  Internet/ACSnet: david@csource.oz.au    Uucp: ..!uunet!munnari!csource!david

I have a motherboard called a Juko Super Turbo running with a v20
processor which has only 1024k.  This machine allows me to configure it
with 640k of conventional memory PLUS a 384k RAMdrive (uses a special
driver shipped with the motherboard) which starts at 640k.

I have no idea how it does this, but it does.

Regards,

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Phillip A. McReynolds,                  sophist@brainiac.raidernet.com
Licensed Philosopher              org:  Phillip's Philosophy Shop, Inc.
(MPA Certified)                "Quality Philosophy Products Since 1990"
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