Re: Use 3GB or 4GB RAM in 32 bit OS?

On Mon, 31 Mar 2008 22:35:48 -0400, Yousuf Khan <bbbl67@[EMAIL PROTECTED]
> put
finger to keyboard and composed:

>Franc Zabkar wrote:
>> My Internet PC is an old socket 7 box with a Diamond Stealth III S540
>> PCI card. Win98's Device Manager shows that it is using the following
>> memory resources:
>> 
>>  FFA80000 - FFAFFFFF  --- 512KB
>>  F0000000 - F7FFFFFF  --- 128MB (video RAM ???)
>>  08020000 - 0802FFFF  ---  64KB
>>  000C0000 - 000CAFFF  ---  44KB (video ROM BIOS extension)
>>  000B0000 - 000BFFFF  ---  64KB (video RAM below 1MB)
>>  000A0000 - 000AFFFF  ---  64KB (video RAM below 1MB)
>> 
>> Lavalys Everest tells me that the video adapter has 32MB of RAM which
>> leads me to wonder why the card's memory address space (128MB) is so
>> large.
>
>
>I think the old DOS-based Windows OSes used a different memory
>management scheme. Back then they used to map the memory mapped i/o
>devices to the range between 640KB and 1MB. I think with the newer
>Windows, that's all remapped in the range between 3GB and 4GB.
>
>The whole missing 4th Gigabyte issue is reminding me of the days of the
>transition from 16-bit to 32-bit os, when people were running into the
>same issues, except at lower address ranges. History doesn't repeat 
>itself, it just rhymes.
>
>	Yousuf Khan

The following memory resources are re****ted by msinfo32.exe in a P4
Windows XP box. You can see that the NVIDIA graphics device still
utilises the 0xA0000-0xBFFFF memory address range below the first MB.
If I understand things correctly, then the maximum amount of memory
that could be available to Windows XP in a fully populated system
would be 0xDC800000, ie 3.445 GB.


[Memory]

Resource                Device

0xA0000-0xBFFFF         PCI bus	
0xA0000-0xBFFFF         Intel(R) 82865G\PE\P Processor to AGP
Controller - 2571	
0xA0000-0xBFFFF         NVIDIA GeForce FX 5200	
0x20000000-0xFFFFFFFF   PCI bus	
0xFC900000-0xFE9FFFFF   Intel(R) 82865G\PE\P Processor to AGP
Controller - 2571	
0xDC800000-0xEC7FFFFF   Intel(R) 82865G\PE\P Processor to AGP
Controller - 2571	
0xF0000000-0xF7FFFFFF   Intel(R) 82865G\PE\P Processor to AGP
Controller - 2571	
0xFD000000-0xFDFFFFFF   NVIDIA GeForce FX 5200	
0xE0000000-0xE7FFFFFF   NVIDIA GeForce FX 5200	
0xFEBFFC00-0xFEBFFFFF   Standard Enhanced PCI to USB Host Controller	
0xFEAFFC00-0xFEAFFCFF   Lucent Win Modem	
0xFFB80000-0xFFBFFFFF   Intel(r) 82802 Firmware Hub Device	
0xFFF80000-0xFFFFFFFF   Intel(r) 82802 Firmware Hub Device	
0xFEC00000-0xFEC00FFF   Motherboard resources	
0xFEE00000-0xFEE00FFF   Motherboard resources	
0xFED20000-0xFED9FFFF   Motherboard resources	
0xFFEFFC00-0xFFEFFFFF   Intel(R) 82801EB Ultra ATA Storage Controllers
0xFEBFF800-0xFEBFF9FF   SoundMAX Integrated Digital Audio	
0xFEBFF400-0xFEBFF4FF   SoundMAX Integrated Digital Audio	
0x0000-0x9FFFF          System board	
0xC0000-0xDFFFF         System board	
0xE0000-0xFFFFF         System board	
0x100000-0x1FFFFFFF     System board	

- Franc Zabkar
-- 
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