On Saturday, September 10, 2016 at 9:23:26 AM UTC-4, Mayayana wrote:
"Terry Coombs" wrote

| It is a limitation of 32 bits, applies more or less equally to any OS.
|
| Thanks , I did download a 64 bit version of Ubuntu 16-04 LTS earlier just
| in case .


More specifically, it's a limitation in addressing.
Stored data in RAM is stored at a memory "address".
Those addresses are critical and ubiquitous in
system functions. To send or receive data from the
system an address pointer is often required. A 32-bit
OS uses a 32-bit "long" integer for those pointers.
It's a 32-bit OS because a 32-bit/4byte integer is
the common currency for data.
So the limitation is simply that a number can't be
specified beyond about 4 billion. There's no way to
point to data stored in RAM at the 5 billionth byte.

Allowing for some sharing of RAM for graphics, that
often works out to about 3.2 GB addressable RAM.

While it's true that 32 bit addressing thing is the root cause,
it's not true that it's impossible to have more than 4GB
of RAM because of it. All Intel CPUs since the Pentium II have
supported more than 4GB of physical memory, it had a 36 bit
address bus. The instruction set works with 32 bit addresses,
32 bit data, but the addresses get mapped by the MMU into a physical
memory address space of 64GB. OS's that support virtual memory can
take advantage of it, if the OS designers choose to do so.