Win-DOHS 95, 98 and ME all use a segmented memory model. The System, User and GDI resources are stored in their own segment of your system RAM, and the other segment is general purpose. Regardless of how much RAM you put in the machine, the System, User and GDI segment never increases. "Picture" below explains:
128 MB = | S/U/GDI seg | General Purpose Seg |
256 MB = | S/U/GDI seg | General Purpose Seg General Purpose Seg |
512 MB = | S/U/GDI seg | General Purpose Seg General Purpose Seg General Purpose Seg General Purpose Seg |
This can easily be seen by starting up a Win95/98/ME computer with 128 MB installed, loading some programs and noting the amount of System, User and GDI resources that are available. Then install 256 MB and/or 512 MB, and start up the same programs again. The free System, User and GDI resource numbers will be exactly the same. This is because that resource area of the system memory does not change in size even when the total amount of RAM installed does. Extremely stupid setup, but what do you expect from M$.
I work at a company that still uses Win-DOHS 95 in abundance on their PCs. I cannot run MS Outlook, OpenTime, TrackView, Exceed and RapidSQL at the same time on my machine because the S/U/GDI resources run out when I start RapidSQL. My computer was upgraded from 128 MB to 256 MB in an attempt to "fix" this. Unfortunately, the above description of the memory model reared its ugly head, and the same problem happens even with the additional memory.
I've read lots of reports that say the max amount of RAM Win98 can use is 256 MB. Whether they're correct or not is anybody's guess. If you're able to run with 512 MB, like JJ mentions, you might simply be lucky.
On the other hand, Win-DOHS 2000 and XP have a "Flat" memory model. All of the system RAM is general purpose. There is no extremely small System, User and GDI resource area to run out when you need it most. The only exception to this rule that I can think of off the top of my head is when your system has integrated video that uses the system RAM for its video memory. To make a long story short, if you need to use a lot of RAM and you need to use Win-DOHS, you'll have to use Win-DOHS 2000 or XP to get the most benefit.
