Alan - Thanks for reminding about PAE; certainly my "other than with tricky added hardware and software that is largely now irrelevant" is wrong as to "tricky" and "irrelevant", since the PAE kernels speak to both. Also, swapping quickly among running programs should be solved by PAE where it is supported. So only my point about a single program being restricted to 4GB is probably relevant. Apologies for so much noise to say that.
Alan - Thanks for reminding about PAE; certainly my "other than with tricky added hardware and software that is largely now irrelevant" is wrong as to "tricky" and "irrelevant", since the PAE kernels speak to both. Also, swapping quickly among running programs should be solved by PAE where it is supported. So only my point about a single program being restricted to 4GB is probably relevant. Apologies for so much noise to say that.