directory structure of R 2.12.0 distribution

On Wed, Dec 8, 2010 at 11:43 AM, Kevin R. Coombes
<kevin.r.coombes at gmail.com> wrote:

Hi,

On my 64-bit machine, there are two subdirectories:
   i386
   x64
I usually want to use the 64-bit executable.  However, some packages have
not yet been compiled for a 64-bit machine, so for those I need to use the
32-bit i386 subdirectory.

Thanks.

Is there something at installation time that says which to use?

No, that's up to the user.  If you want to run 32 bit R, use i386.  If 
you want to run 64 bit R, use x64.  (You need to be on 64 bit Windows 
and to have chosen to install both to have this choice.)

Is there a registry entry?

There's an entry in the 32 bit registry if you install 32 bit R, and one 
in the 64 bit registry if you install 64 bit R.  Writing R Extensions 
discusses this.

Is this documented anywhere?

It was announced in the CHANGES file, and there's a description in the R 
Admin manual as well as the Writing R Extensions manual.

Duncan Murdoch