Add booting instructions for sparc64. Copied pretty much verbatim

from the installation notes for CURRENT, modulo arch="sparc64"
attributes being removed.

en_US.ISO8859-1/books/handbook/install/chapter.sgml

@@ -998,6 +998,61 @@ Booting [kernel] in 9 seconds... _</screen>
 
       </sect3>
 
+      <sect3>
+	<title>Booting for &sparc64;</title>
+
+    <para>Most sparc64 systems are set up to boot automatically from
+      disk.  To install &os;, you need to boot over the network or
+      from a CDROM, which requires you to break into the PROM
+      (OpenFirmware).</para>
+
+    <para>To do this, reboot the system, and wait until the boot
+      message appears.  It depends on the model, but should look about
+      like:</para>
+
+    <screen>Sun Blade 100 (UltraSPARC-IIe), Keyboard Present
+Copyright 1998-2001 Sun Microsystems, Inc.  All rights reserved.
+OpenBoot 4.2, 128 MB memory installed, Serial #51090132.
+Ethernet address 0:3:ba:b:92:d4, Host ID: 830b92d4.</screen>
+
+    <para>If your system proceeds to boot from disk at this point, you
+      need to press <keycombo
+      action="simul"><keycap>L1</keycap><keycap>A</keycap></keycombo>
+      or <keycombo
+      action="simul"><keycap>Stop</keycap><keycap>A</keycap></keycombo>
+      on the keyboard, or send a <command>BREAK</command> over the
+      serial console (using for example <command>~#</command> in
+      &man.tip.1; or &man.cu.1;) to get to the PROM prompt.  It looks
+      like this:</para>
+
+    <screenco>
+      <areaspec>
+	<area id="prompt-single" coords="1 5">
+	<area id="prompt-smp" coords="2 5">
+      </areaspec>
+
+      <screen><prompt>ok     </prompt>
+<prompt>ok {0} </prompt></screen>
+
+      <calloutlist>
+	<callout arearefs="prompt-single">
+	  <para>This is the prompt used on systems with just one
+	    CPU.</para>
+	</callout>
+
+	<callout arearefs="prompt-smp">
+	  <para>This is the prompt used on SMP systems, the digit
+	    indicates the number of the active CPU.</para>
+	</callout>
+      </calloutlist>
+    </screenco>
+
+    <para>At this point, place the CDROM into your
+      drive, and from the PROM prompt, type <command>boot
+      cdrom</command>.</para>
+
+      </sect3>
+
     </sect2>
 
     <sect2 id="view-probe">