On the downloads page, you have the following two options:
- 64-bit
- 32-bit (for machines with less than 2GB RAM)
Assuming you have a 32-bit machine with the maximum 4GB of RAM, will Ubuntu will work on that?
By default, any 32-bit OS cannot index more than 4Gb of RAM and Ubuntu is not exclusion.
But Ubuntu has 2 different kernels: standard and patched(Physical Address Extension - PAE). Now Ubuntu 32-bit used this patched kernel by default and so it can manage up to 64Gb of RAM.
And Ubuntu websites says 32-bit (for machines with less than 2GB RAM) because of RAM usage. 64-bit software use a more RAM than 32-bit.
Clean Ubuntu 32-bit installation (Unity) use about 600Mb of memory, 64-bit installation takes about 100Mb more. And for modern software 2Gb of RAM is not so much and it can easily be used(say 10 tabs in Chrome can use a lot of RAM).
That's why Ubuntu website recommends use 32-bit for computers with less than 2Gb of RAM. But that doesn't mean you cannot install Ubuntu 64-bit on such computer configuration.
