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Aug28Written by:Martin
28.08.2007 10:32 
A few days ago I got two additional gigs of RAM for my main development machine doubling the RAM to 4GB total. However, Windows Vista only recognized about 3.5GB. Everybody knows that with 32bit one gets 4GB of address space. But where went the ca. 500MB on my system? I did some serious researchused Google to find out. Here’s the result: Most of that 4GB address space is filled with RAM, but there are memory-mapped devices such as video cards which need some address space too. The BIOS probably uses some address space as well. That’s no problem when you have only two or three gigs of RAM, because everything fits well into the whole address space. But with 4GB RAM it obviously does not. It would be possible to address the entire RAM with the Windows /PAE option, but applications have to explicitly support this. The 4GB restriction is still true for modern 64bit processors like the Intel Core 2 Duo in my development machine when they’re running in 32bit mode. But with a 64bit OS, the processor runs in 64bit mode and can theoretically address 264 ≈ 1.6x1019 Bytes, which are 1.6 exabytes. I planned to use Vista x64 since I got the Intel Core 2 Duo machine last year, so now seems to be the right moment to switch. Therefore, since yesterday my main development machine runs no longer runs Windows Vista Business 32bit but the x64 Edition. Direct update from the 32bit Edition was not possible, so I had to install it from the scratch. However, thanks to Windows Easy Transfer migrating all important data and settings was easy (sic!). Unfortunately Windows Easy Transfer is somewhat slow. It took several hours to restore my user account’s settings and data. I used a network share as data storage. That probably slowed things down, too.
The next weeks will show if everything works as smoothly as before. Tags: |
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