From: pb@excelsior.xs4all.nl.REMOVE-THIS (Marc van den Dikkenberg)
Subject: Re: virtual arrays - they're SLOW or I'm dumb
 
On 26 Apr 1998 12:19:31 EDT, John Fritz  wrote:
 
>I just got Power Basic 3.5. I love the possibility of using Mbyte
>arrays with Virtual Arrays, but access seems to be about 15 times SLOWER
>than for regular arrays.
 
>	I am using EMM386.EXE for my memory manager. Has anyone tried other
>memory managers? Do they access Virtual Arrays fast? If you don't know,
 
I don't know about the exact speed difference, but one thing is certain:
when you access XMS/EMS, it's bound to be a lot slower then using the
<640KB base memory.
 
The only way you can access EMS is by swapping data from above the 1 MB
border into a small area of memory below the 640KB. That's a 64KB chunk or
so. Especially when you need to access a lot of data, and there are a lot
of swaps, this will be significantly slower then when your data is in an
area that can be accessed directly.
 
Basicially, all of this is just because the PC platform is still backwards
compatible to the 8088/8086 XT systems, which had no way of addressing
memory above the 1MB border...
 
 
--
Marc van den Dikkenberg
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