🚀 go-pugleaf

In article <5YCCRWV@drivax.UUCP> liberato@drivax.UUCP (Jimmy Liberato) writes:
>darcy@druid.uucp (D'Arcy J.M. Cain) writes:
>
>>In article <88@slvblc.UUCP> dick@slvblc.UUCP (Dick Flanagan) writes:
>>>
>>>I have two of the Everex RAM-3000 boards.  They are EXTended memory boards,
>>>*not* EXPanded memory boards.  LIM in any form is not supported on the board.
>
>>This is almost true.  Although expanded memory was originally designed as
>>a hardware bank switching scheme, the LIM spec  allows any sort of memory
>>to be used as expanded.  There are many programs that allow any type of
>>extended memory to be used as expanded and I believe that Everex includes
>>one with the RAM-3000.  This is the LIM support referred to.
>
>Right.  When they started including a LIM 4.0 driver with it they started
>calling it Ram 3000 Deluxe.  As others have mentioned, there are some
>programs that balk at software emulation of 4.0 LIM.  The cheap boards
>are always either 3.2 LIM with a 4.0 driver or extended memory with 4.0
>emulation.  One interesting point, old AST Rampage EEMS boards give true
>hardware level support for LIM 4.0 when paired up with a new 4.0 driver.
>
>On a related subject, I am now seeing high DOS memory (640-1024K) being 
>refered to as extended memory, at least on AT class machines with 1 Meg
>of memory on the motherboard.  The POST test on an DTK AT clone even
>categorizes this memory as extended memory.  I have heard it refered to
>variously as high memory, video memory, and bios memory.  All these
>make some sense but is it strictly correct to ever refer to these blocks
>of memory as extended?  Is this simply a loose and generic use of the 
>term?  Is this physical memory simply being mapped beyond the FFFFF
>address, that is does the extra 384K actually start at the 100000 address?
>If I were to add a 1 Meg extended memory board would I actually have 1408K?
>
>Am I confusing physical memory (the 384K of extra ram in those chips) with
>logical memory (the reserved adresses for video and bios)? 
>

Most systems today have what is referred to as "Split Memory Addressing". The
part of ram that would normally fall into the contiguous 640K to 1024K address
range is actually re-mapped (through some clever address decoding in the
hardware) to be above 1024K. Because of this, it IS true extended memory. Some
old AT clones could not do this, therefore a 1024K systems of this type
only resulted in a useable 640K out of the total 1024K since the area between
640K and 1024K is reserved for BIOS, video, etc.


Russ Poffenberger               DOMAIN: poffen@sj.ate.slb.com
Schlumberger Technologies       UUCP:   {uunet,decwrl,amdahl}!sjsca4!poffen
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