machine identification

diff --git a/how_to_get_the_programming_languages_running_on_your_computer.mdwn b/how_to_get_the_programming_languages_running_on_your_computer.mdwn
index b4a4962..f9fa2d4 100644 (file)
--- a/how_to_get_the_programming_languages_running_on_your_computer.mdwn
+++ b/how_to_get_the_programming_languages_running_on_your_computer.mdwn
@@ -3,7 +3,7 @@
 We'll assume you're using either Mac OS X, or Windows, or Linux.
 
 If you're using **Mac OS X**, take note of what version of the Mac OS you're
 We'll assume you're using either Mac OS X, or Windows, or Linux.
 
 If you're using **Mac OS X**, take note of what version of the Mac OS you're

-running:
+running. (Under the Apple Menu, select "About this Mac".)

 
 *    Leopard (10.5)
 *    Snow Leopard (10.6)
 
 *    Leopard (10.5)
 *    Snow Leopard (10.6)


@@ -12,29 +12,39 @@ running:
 *    Mavericks (10.9)
 *    Yosemite (10.10)
 
 *    Mavericks (10.9)
 *    Yosemite (10.10)
 

+If you're running **iOS**, you probably can't use this software on that machine. (A bit more below.)
+

 Furthermore, you'll be in one of two subgroups:
 
 *      You'll have Apple's Xcode and the independent MacPorts system
        installed. (Probably you don't. If you don't know what I'm talking about, you don't have these.)
 
 Furthermore, you'll be in one of two subgroups:
 
 *      You'll have Apple's Xcode and the independent MacPorts system
        installed. (Probably you don't. If you don't know what I'm talking about, you don't have these.)
 

+       If you don't have these, but want to try this route, you can read about
+       the MacPorts system at <http://www.macports.org/>.
+       This automates the building of Unix-type software on your Mac; it
+       makes it a lot easier to check for dependencies, use more-recent
+       versions of things, and so on. (Though as it happens, MacPorts only has an older version of
+       our chosen implementation of Scheme.)
+

        Xcode is available at
        Xcode is available at

-       <http://developer.apple.com/technologies/tools/xcode.html>. Some versions of this have been available for free, though you do have to register with Apple as an "Apple Developer", which involves accepting a legal agreement with Apple. I have an older version of this installed. If you download a recent version, email me and let me know how the process works so I can tell others. There are instructions about how to get Xcode in the MacPorts installation guide (see below).
+       <http://developer.apple.com/technologies/tools/xcode.html>. Some
+       versions of this have been available for free, though you do have to
+       register with Apple as an "Apple Developer", which involves accepting a
+       legal agreement with Apple. I have an older version of this installed.
+       If you download a recent version, email me and let me know how the
+       process works so I can tell others. There are instructions about how to
+       get Xcode in the MacPorts installation guide.

        <!--
        The latest version of Xcode to work with Leopard is 3.14; more
        recent versions (>= 3.2) require Snow Leopard. 3.2.6 is last version that can be downloaded for free by users of 10.6 / Snow Leopard. (But if they pay, they can use up to Xcode 4.2.)
        Xcode 4.1 was free to all users of 10.7 / Lion. Is Xcode 4.6.x still available for free? Are Xcode 5.x and/or 6.x available for free?
        -->
 
        <!--
        The latest version of Xcode to work with Leopard is 3.14; more
        recent versions (>= 3.2) require Snow Leopard. 3.2.6 is last version that can be downloaded for free by users of 10.6 / Snow Leopard. (But if they pay, they can use up to Xcode 4.2.)
        Xcode 4.1 was free to all users of 10.7 / Lion. Is Xcode 4.6.x still available for free? Are Xcode 5.x and/or 6.x available for free?
        -->
 

-       The MacPorts system is available at
-       <http://www.macports.org/>.
-       This automates the building of Unix-type software on your Mac; it
-       makes it a lot easier to check for dependencies, use more-recent
-       versions of things, and so on.

 
 

-*      Or you won't have those installed. (Most Mac users will be in this group.)
+*      Or you won't have those installed. (**Most Mac users will be in this group.**)

        Then you'll need pre-packaged (and usually pretty GUI) installers for
        everything. These are great when they're available and kept up-to-date;
        Then you'll need pre-packaged (and usually pretty GUI) installers for
        everything. These are great when they're available and kept up-to-date;

-       however those conditions aren't always met.
+       however sometimes those conditions aren't met.

 
 
 If you're using **Windows**, you'll be in one of two subgroups:
 
 
 If you're using **Windows**, you'll be in one of two subgroups:


@@ -63,6 +73,13 @@ systems.
        i686 or i386 or whatever) version of Linux, and that I'm running kernel
        version 3.12.8.
 
        i686 or i386 or whatever) version of Linux, and that I'm running kernel
        version 3.12.8.
 

+**For all of these groups**, a general item to take note of is what "processor architecture" your machine is running. Three of the possibilities are:
+
+*       One of Intel's i386, i486, i586, i686 architectures. These are collectively known as "x86" or "IA-32" or sometimes just "32-bit".
+*       Intel or AMD's x86\_64 architecture. This is sometimes also called "x64" or "amd64" or "IA-64" or sometimes just "64-bit".
+*       ARM or some other architecture. These are generally lower-powered machines, like iPads. Some of the software we're proposing *might* in principle be capable of running on such machines, but installers don't seem to be available. We'll assume you have access to an x86 or x86\_64 machine.
+
+In the Linux example above, I could tell my machine is running x86 because the result of the `uname` command said "i386" at the end. Another machine I have says "x86\_64" at the end. On a Mac, you can also say `uname -m` in a Terminal session, and it will say something like "i386". I think that Mac OS's from Lion / 10.7 forward have all been x86\_64-only. On Windows, I don't know how to collect this information. But generally, machines running Windows XP will probably be i386/32-bit (unless it's a version of Windows with "64-bit" or "x64" in its title); machines running Windows Vista or Windows 7 or Windows 8 could be running either x86/32-bit or x64/64-bit.

 
 
 ## PLEASE REPORT PROBLEMS (AND SOLUTIONS!) ##
 
 
 ## PLEASE REPORT PROBLEMS (AND SOLUTIONS!) ##