Explicitly list the i/o addresses of the serial ports.

Prompted by docs/12343, in which people seemed to get a little confused.
The original text in the file said:

[...]
# By default we use COM1 as our serial console port *if* we're going to use
# a serial port as our console at all.  (0x3E8 = COM2)
#
#BOOT_COMCONSOLE_PORT= 0x3F8
[...]

From what I can make out, some people have assumed that means that if
they just uncomment the BOOT_COMCONSOLE_PORT then it will use COM2:
These same people then assume that "0x3F8" on that line is a typo for
"0x3E8".

What it actually means is that if you uncomment the line then the default
stays as "Ox3F8" (COM1:), and that you have to uncomment the line, *and*
change the value of the variable in order to use COM2:.

So I've made that a little bit clearer.  I've also listed the hex values
for COM1: thru COM4:, snarfed from sys/isa/isareg.h.

PR:             docs/12343
Submitted by:   Bill Grunfelder <wjgrun@dippy.cyberwar.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/share/examples/etc/make.conf b/share/examples/etc/make.conf
index 6387d85..c6c3c7d 100644
--- a/share/examples/etc/make.conf
+++ b/share/examples/etc/make.conf
@@ -1,4 +1,4 @@
-# $Id: make.conf,v 1.80 1999/06/01 02:55:42 billf Exp $
+# $Id: make.conf,v 1.81 1999/06/04 03:17:04 billf Exp $
 #
 # This file, if present, will be read by make (see /usr/share/mk/sys.mk).
 # It allows you to override macro definitions to make without changing
@@ -76,7 +76,9 @@
 # serial port in addition to or instead of the keyboard/video console.
 #
 # By default we use COM1 as our serial console port *if* we're going to use
-# a serial port as our console at all.  (0x3E8 = COM2)
+# a serial port as our console at all.  Alter as necessary.
+#
+#   COM1: = 0x3F8, COM2: = 0x2F8, COM3: = 0x3E8, COM4: = 0x2E8
 #
 #BOOT_COMCONSOLE_PORT=	0x3F8
 #