Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mjbtn!raider!brainiac!sophist
From: sophist@brainiac.raidernet.com (sophist)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: extended memory
Message-ID: <gT9gu2w163w@brainiac.raidernet.com>
Date: 20 Dec 90 12:06:27 GMT
References: <768@csource.oz.au>
Organization: Phillip's Philosophy Shop, Nashville TN
Lines: 49

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"
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =