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SPECIAL COMPUTER FEATURE
Dual boot
for your PC
By Greg Swain
Windows 95 or Windows 3.1x? – install a
dual-boot system and it’s your choice
Want to upgrade
to Windows 95
but fear the
unknown? A dual
boot system may
be the answer.
Let’s make one thing clear right
from the outset: Windows 95 is quite
different to Windows 3.11, so don’t
expect more of the same.
Even an experienced 3.11 user will
have to spend some time coming to
grips with the new interface. For this
reason, many PC users have been
reluctant to take the plunge into Windows 95, particularly if they need their
computer for work.
Another concern for many people
is that an important appli
cation or
hardware item might not run properly
under Windows 95. That problem can
invariably be solved by upgrading
Don’t be fooled by the
spartan look of the
desktop when you first
install Windows 95. It’s
far more user friendly
than the old Windows
3.1x interface and you
can easily customise it
by adding shortcuts to
your drives, programs,
and utilities, or even to
individual documents.
Everything else is
normally accessed via
the Start button.
4 Silicon Chip
the application or, in the case of a
hardware item, installing new drivers.
The drawback is that you usually only
find this out after you’ve installed
Windows 95 and that means lost time.
The pros & cons
Although there are some drawbacks,
a dual-boot system has several advantages, especially if you are new to
Windows 95. First, it lets you explore
the new interface and become familiar
with it at your own pace. If you need
to produce some useful output during
this learning phase, then it’s simply
a matter of rebooting to switch back
to the more familiar Windows 3.11
territory.
Second, you can keep all your 3.11
applications and gradually test each
one in turn by installing it under the
new operating system. In some cases, it
will be necessary to obtain an upgrade
to avoid problems, although most
software should operate satisfactorily.
However, it’s nice to know that you
can go back to the old Windows 3.1x
interface if a particular application
does prove troublesome.
Finally, you can check that all your
peripheral devices (scanners, modems, SCSI controllers, soundcards,
etc) operate satisfactorily under Win-
The Basic Steps To A Dual-Boot System
❶
dows 95. Most setups will be relatively
hassle-free, although it may be necessary to retain the old 16-bit drivers in
some cases. We’ll have more to say on
this subject a little later on.
So should you go for a dual-boot
system or not? If you absolutely cannot afford computer downtime and
you have lots of hard disc space, the
answer is a qualified yes. A dual-boot
system is not for everyone though.
Opting for Windows 95 as the sole
operating system is usually a very safe
choice, so weigh up the pros and cons
of a dual-boot system carefully before
making a decision.
Space requirements
One important thing to consider
before plowing ahead is how much
space you have left on your hard disc.
The Windows 95 oper
ating system
requires about 50Mb or so of hard disc
space. On top of that, you will have to
reinstall all your applications to get
them to run under Windows 95.
This means that, for 32-bit applications at least, you will end up with
two versions of the same program on
the hard disc – one version for each
operating system (note: 16-bit applications can be generally be reinstalled
into the same directory as before, to
save space).
By now, you will be starting to realise that a dual-boot system can quickly
gobble up hard disc space. Of course,
once a program is up and running
under Windows 95, the old Windows
3.1x version can be deleted, so a great
deal of that hard disc space can easily
be regained. After all, there’s little
reason to retain two working versions
of the same program.
A new hard disc
If hard disc space is a little tight,
then you should consider installing
a second hard disc (ie, a D: drive).
Windows 95 and your various applications can then be installed on this
D: drive. This approach simplifies
the installation of a dual-boot system somewhat (see Corrupt Swapfile
Work
around) and is also less confusing since most of the files for the
two operating systems are kept well
separated.
Fig.1: when you
install Windows
95, the Setup
Wizard takes
over and guides
you step-bystep through the
procedure.
❷
Fig.2: choose
Other Directory
when this dialog
box appears to
prevent your
old c:\windows
directory from
being overwritten.
❸
Fig.4: pressing F8
when the “Starting
Windows 95”
message appears
brings up this
Startup Menu.
Option 1 launches
Windows 95, while
option 7 launches
MS-DOS, after
which you can
launch Windows
3.1x.
Fig.3: enter in
the directory
where you want
Windows 95
installed and
then complete the
rest of the setup
procedure.
❹
Microsoft Windows 95 Startup Menu
1.
2.
3.
4.
5.
6.
7.
Normal
Logged (\BOOTLOG.TXT)
Safe mode
Step-by-step confirmation
Command prompt only
Safe mode command prompt only
Previous version of MS-DOS
Enter a choice: 7
July 1996 5
Table 1: System File Names
MS-DOS Filename
Filename Under Win95
Win95 Filename
Filename Under "Old DOS"
autoexec.bat
autoexec.dos
autoexec.bat
autoexec.w40
command.com
command.dos
command.com
command.w40
config.sys
config.dos
config.sys
config.w40
io.sys
io.dos
io.sys
io.w40
msdos.sys
msdos.dos
msdos.sys
msdos.w40
mode.com
mode_dos.dos
Big hard disc drives are dirt cheap
right now, so this is an option that
deserves serious consideration.
Spring-clean the disc
Before installing Windows 95, your
hard disc should be given a good
clean-up.
(1) Delete all junk files from the
disc, including bak files, duplicate
files and any programs that are no
longer used.
An uninstall program is handy here,
since it will quickly find duplicates
and orphan files (ie, files that are no
longer required by the system). There
are several around but make sure that
it will work under Windows 95 if you
plan to buy.
(2) Delete the permanent swapfile
(assuming that you have one). You
do this via the Control Panel – just
double-click the Control Panel icon,
double-click the 386 Enhanced icon,
click the Virtual Memory button, then
click the Change button. Now go to
New Swapfile Settings, choose None
from the Type menu, click OK and
reboot the computer for the changes
to take effect.
This will free up the disc space
that was previously allocated to the
swapfile.
(3) Run the Scandisk and Defrag
Table 2: MSDOS.SYS Values
Entry
Description
[Paths] section:
WinDir=
Defines the location of the Windows 95 directory, as specified
during setup.
WinBootDir=
Defines the location of the startup files.
HostWinBootDir=
Defines the location of the boot drive root directory.
[Options] section:
BootMulti=
Enables/disables dual boot capabilities. The default is 0.
Changing this entry to 1 enables the ability to start MS-DOS
by pressing F4; alternatively, pressing F8 gives the Windows
95 Startup Menu.
BootGUI=
Enables automatic graphical startup into Windows 95.
BootMenu=
Enables/disables automatic display of the Windows 95 Startup
Menu. The default is 0. Setting this value to 1 eliminates the
need to press F8 to see the menu.
BootMenuDefault=
Sets the default menu item on the Windows Startup Menu.
Set this value to 1 if you normally boot straight to Windows
95, or to 7 (or 8) if you normally boot to MS-DOS.
BootMenuDelay=
Sets the number of seconds for which the Windows Startup
Menu is displayed before running the default menu item. A
value of 5-7 seconds is usually suitable.
6 Silicon Chip
utilities. What’s that, you’ve never run
these utilities? Shame on you. Here’s
what to do: exit Windows and, at the
c:> prompt, type
scandisk c: /autofix
Then, when scandisk has finished
running, type
defrag c: /f
For further information on these two
utilities, type help scandisk or help
defrag at the DOS prompt.
(4) Check for viruses (this is most
important). To do this job properly,
you should use an up-to-date virus
checker such as McAfee’s Viruscan,
Norton Anti-Virus or ThunderByte.
If you don’t have an up-to-date virus
checker, then at least run the Microsoft
Anti-Virus (MSAV) utility that comes
bundled with DOS6.x. It’s better than
nothing (if only just) and will at least
find some of the older, more common
viruses.
There’s just one more thing to do
before tearing the shrinkwrap off the
Windows 95 Upgrade pack – clean up
your system files. First, make backup
copies of autoexec.bat and config.
sys on a floppy disc then, using a
text editor, open each file in turn and
“rem” out anything that obviously has
nothing to do with Windows 95 (eg,
Dosshell).
You can also “rem” out environment
statements and anything to do with
memory management but it’s best to
leave the device drivers in place unless
you know what you are doing.
If in doubt, leave it in. When you
install Windows 95, it creates its
own autoexec.bat and config.sys files
based on the originals and these new
files can easily be edited later on (see
panel).
A foot in both camps
Setting up a dual-boot system so
that you can run either Windows 95
or Windows 3.11 is easier than you
think. The best way to achieve this is
to first install Windows 3.1x and then
install the Windows 95 Upgrade pack.
Do not attempt to use the full version or an OEM version of Windows
95, as this will install over the top of
your previous DOS and Windows 3.1x
directories.
The installation procedure is quite
straightforward. First, boot your
machine to the C:> prompt and run
the Windows 95 setup program as
described in the manual. The Setup
Wizard (see Fig.1) then takes over and
guides you step-by-step through the
installation.
To install a dual-boot system, simply select Other Directory when the
Choose Directory dialog box appears,
then specify a new directory that does
not have your previous version of
Windows in it. An obvious choice is
c:\win95 or d:\win95 if you have in
stalled a second hard disc specifically
for Windows 95.
Make sure that you don’t choose
the default c:\windows directory if
that is where your old Windows 3.1x
resides. If you do, then Windows 95
will overwrite the old Windows installation and you can say goodbye to
your dual-boot aspirations.
Corrupt Swapfile Workaround
On some dual-boot systems, a corrupt swapfile warning message may
appear when Windows 3.1x is started after running Windows 95. The reason
for this is that Windows 95 can make changes to the swapfile (386SPART.
PAR) that the previous version of Windows does not recognise.
There are several ways of beating this problem.
(1) Delete the permanent swapfile and create a temporary one. To do this,
first delete the corrupt swapfile when prompted. Next, after Windows 3.1x
starts, launch the Control Panel, double-click the 386 Enhanced icon, click
virtual Memory, click Change and choose the temporary swapfile setting.
(2) Install Windows 95 on a separate hard disc drive, so that it cannot
interfere with the Windows 3.1x swapfile.
(3) Delete the corrupt swapfile and create a new permanent swapfile in
Windows 3.1x, then use a text editor to add the following lines to the [386Enh]
section of the Windows 95 SYSTEM.INI file:
PagingFile=<Win31xPagingFile>
MinPagingFileSize=<SizeInK)
where <Win31xPagingFile> is the name of the swapfile (usually C:\386SPART.
PAR) and <SizeInK) is the size of swapfile divided by 1024.
All you have to do now is continue
with the setup procedure as normal.
It’s as simple as that – well, almost!
There are a few tweaks to be made
later on, as we shall see.
By specifying a different destina-
tion directory, the Windows 95 setup
procedure automatically makes all
the necessary changes to preserve
your existing versions of MS-DOS and
Windows 3.1x. This includes retaining
your current autoexec.bat, config.sys,
Clean Up Those System Files
By now, you may have discovered
that the new autoexec.w40 and config.w40 files (under “Old Dos”) are
modified versions of your original
autoexec.bat and config.sys files.
Sure, some lines may have been
“remmed” out but there will also be
quite a lot that haven’t been.
What happens is that when you
install Windows 95 onto a computer with an existing DOS/Windows
3.1x setup, it’s pretty conservative
about getting rid of the old 16-bit
drivers for devices such as SCSI
controllers, soundcards, scanners
and network cards – this despite
the fact that Windows 95 includes
hundreds of 32-bit drivers for common devices.
Note that this occurs whether you
are installing a dual-boot system or
a sole operating system based on
Windows 95.
The problem here is that those old
16-bit drivers will slow your system
down. However, there’s an easy
workaround for this – just open your
autoexec.w40 and config.w40 files
(or autoexec.bat and config.sys files
in the case of a sole Win 95 operating
system) and REM each driver and
environment statement in turn.
When this is done, Windows 95
loads its own 32-bit drivers to suit
any hardware devices it finds. Test
your system after each line has
been “remmed” out, to confirm that
Windows 95 has found the relevant
driver and that the system still works
correctly.
If there’s a device that Windows
95 doesn’t recognise, try running
the Add New Hardware wizard from
the Control Panel. If you still don’t
get any joy (eg, a soundcard isn’t
recognised), go back and remove
the REM statement from the relevant device driver or environment
setting item.
Ideally, you should be able to REM
everything out so that you have nothing at all in your autoexec.w40 and
config.w40 files, although a PATH
statement can be handy if you make
frequent excursions to the command
prompt. Anything to do with memory
management (eg, EMM386.EXE
and HIMEM.SYS) can certainly be
removed, as Windows 95 takes care
of memory automatically.
So why doesn’t Windows 95 get
rid of the old drivers in the first
place? The answer is that it leaves
them there just in case it can’t find
a suitable 32-bit driver. By playing
safe, it ensures that all your hardware items continue to work after
installation. It’s up to you to “clean”
the system up if you want maximum
performance.
If it does prove necessary to leave
a 16-bit “real-mode driver” in place,
then at least your hardware will continue to operate while you track down
a suitable Win95 driver. Suitable drivers can often be downloaded from
Internet sites and bulletin boards
or obtained from software vendors.
July 1996 7
Fig.5: Typical Modified MS-DOS.W40 File
[Paths]
WinDir=D:\WIN95
WinBootDir=C:\WIN95
HostWinBootDrv=C
An automatic menu
[Options]
BootMulti=1
BootGUI=1
BootMenu=1
BootMenuDefault=1
BootMenuDelay=7
Network=0
;
;The following lines are required for compatibility with other programs.
;Do not remove them (MSDOS.SYS needs to be >1024 bytes).
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxa
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxb
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxc
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxd
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxe
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxf
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxg
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxh
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxi
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxj
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxk
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxl
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxm
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxn
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxo
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxp
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxq
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxr
;xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxs
win.ini, system.ini and other system
files.
Where necessary, Windows 95
renames these system files for its
own use. For example, in a dual-boot
system, the Windows 95 equivalent
of autoexec.bat is named autoexec.
w40 while running “old DOS”. If
Windows 95 is launched, the original
autoexec.bat file is renamed autoexec.
dos, while autoexec.w40 becomes the
new autoexec.bat.
Similarly, the equivalent Windows
95 file for config.sys is config.w40 under “old DOS”. Table 1 shows how the
various file names change, depending
on whether you are running Windows
3.1x or Windows 95.
Once the installation is complete,
your computer will boot straight into
Windows 95 (by default) each time it
is turned on.
Booting to Windows 3.1x
Believe it or not, you now have an
operating dual-boot system. So how do
8 Silicon Chip
dows 95 in its minimal configuration
(safe mode), boot with step-by-step
confirmation, or boot straight to the
Windows 95 command prompt.
you load your old operating system?
It’s easy – wait until you see the message “Starting Windows 95” appear on
the screen (it’s there for about two seconds) and press F4. Your old version
of MS-DOS will now load, after which
you can remove the “rem” statements
from your original autoexec.bat and
config.sys files.
From here on, you will be able to
load MS-DOS and launch Windows
3.1x just as before, simply by pressing
F4 at the right moment.
Alternatively, you can press F8
when the “Starting Windows 95”
message appears to view the Windows
95 Startup Menu – see Fig.4. This typically presents you with a list of seven
or eight options. If you do nothing,
Windows 95 will automatically boot
up after a delay of 30 seconds (this
delay can easily be changed). If you
want your old DOS, you simply select
“Previous version of MS-DOS” and
press <enter>.
The remaining options boot Win-
Having to press F4 or F8 at the
correct time to boot “Old DOS” is a
bit of pain. Wouldn’t it be nice if the
startup menu could be made to appear
automatically?
Well, in case you haven’t already
guessed, it can. All you have to do is
modify the Windows 95 menu file.
This file lives in the root directory
of the hard disc and is called (oddly
enough) msdos.w40 under “Old Dos”
(or msdos.dos under Windows 95).
Note that this is a hidden, read-only,
system file so you will have to undo
these attributes before modifying the
file. Assuming you are running “Old
Dos”, go to the root directory command
prompt and type:
attrib -r -h -s msdos.w40
You can now open the file with a
text editor and modify it to make the
startup menu appear automatically.
This simply involves adding the line:
BootMenu=1
to the [Options] section of the file.
Table 2 shows a list of some possible
settings while Fig.5 shows a typical
msdos.w40 file. Let’s take a closer look
and analyse the various settings under
the [Options] section if Fig.4:
(1) BootMulti=1 – enables dual-boot
capabilities.
(2) BootGUI=1 – enables automatic
graphical startup into Windows 95.
(3) BootMenu=1 – enables automatic
display that the Windows Startup
Menu, thereby eliminating the need
to press F8.
(4) BootMenuDefault=1 – sets the
default item on the Windows Startup
Menu. In this case, the value is 1 and so
“Normal” (ie, Windows 95) is selected.
Change this value to 7 if you want “Old
DOS” to be the default.
(5) BootMenuDelay=7 – sets the delay
(in seconds) before the default menu
item automatically boots if no further
action is taken. In this case, the value
is seven seconds.
(6) Network=0 – this value should be
0 if no network software components
are installed, or 1 if networking is
installed.
Note that this list is by no means
complete. We’ve only listed the settings that are relevant to this article.
If you like, you can experiment with
other settings from Table 2, to customise your particular setup. And in case
you’re wondering, do not removed
any of the commented lines (ie lines
with a semicolon in front of them)
from msdos.w40. This file needs to be
greater than 1024 bytes for the system
to function correctly.
Don’t forget to restore the msdos.
w40 file attributes when you have
finished; ie, type attrib r h s msdos.
w40 at the DOS prompt.
Giving old Windows the boot
That’s really it – you now have a
fully functioning dual boot system
that will let you explore and optimise
Windows 95 at your leisure. My tip is
that once you get used to the new inter
face and sort out any software hassles,
you will eventually give your old DOS/
Windows 3.1x setup the boot.
Finally, don’t run your old disc
maintenance utilities after you have
installed Windows 95 (Scandisk,
Defrag, etc), as you could wreck your
installation. Windows 95 comes with
itys own disc maintenance utilities
and these should be used instead. In
fact, it’s a good idea to delete the old
utilities, to prevent any accidents. SC
Setting Up Dual Boot Capabilities
After Windows 95 Has Been Installed
Let’s say that you’ve taken the plunge and installed Windows 95 over the
top of your old system but now also want to be able to boot your old MS-DOS.
Fortunately, you can set up a dual-boot MS-DOS/Windows 95 system after
Windows 95 has been installed. You will not be able to use your previous
version of Windows, however.
Although we haven’t tested it, the following procedure should work:
(1) On a bootable floppy disc that starts MS-DOS 5.0 or later, rename the
IO.SYS and MSDOS.SYS files to IO.DOS and MSDOS.DOS, respectively.
Note that these are normally hidden, system, read-only files, so undo these
attributes before modifying them; ie, type attrib -r -h -s IO.SYS and attrib
--r -h -s MSDOS.SYS.
(2) Copy these files to the root directory of your hard disc (ie, to the boot
drive). Important: be sure to rename the files as described in step 1 before
copying them to the hard disc, otherwise you will wreck your existing Windows 95 installation.
(3) Rename the COMMAND.COM file on the bootable floppy to COMMAND.
DOS and copy this to your boot drive.
(4) Use a text editor to create suitable CONFIG.DOS and AUTOEXEC.DOS
files and store them in the root directory.
(5) Edit the MSDOS.SYS file so that the Windows 95 Startup Menu automatically appears during boot-up, as described in the text (see “An Automatic
Menu”).
July 1996 9
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