What factors determine the maximum amount of physical memory a system can have? [closed]

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What factors determine the maximum amount of physical memory a system can have? I know the operating system and the hardware play a roll. For hardware does it come down to the number of lines in the address bus?

According to this website different versions of Windows 7 have differnet caps on the usable memory, but what I don't get is why they don't corolate with the 32 bit/64 bit version? For example why does Home Premium support up to 16GB and Professional up to 192GB when both are 64 bit?

Is the max the lower of the two: hardware and operating system? For example what would happen if you had a 32bit address bus and put in 8GB of ram and had Windows 7 64bit?

Answer 1

Any 32 bit systems will not recognise anything more than 4GB. You can put whatever you want in it, but you will only get 4GB usable (actually a little less). Regarding Windows, it is merely a marketing restriction. If Home Premium would support 192GB who would buy Professional? It like if your Toyota Yarris could do 300 km/h in 10 seconds why would you buy Ferrari? :-)