Ref: 08720026
Title: Installing OS/2 1.21 and OS/2 1.1 for Dual Booting
Date: 9/28/90

Copyright 3Com Corporation, 1991.  All rights reserved.

It is possible to install both OS/2 1.21 (using HPFS) and OS/2 1.1
(using FAT) on the same hard drive, and to switch easily between the
two.  This article explains how to configure a single machine to
serve as a concurrent LAN Manager 1.1 server (using a FAT file system
and 3Com's server adapted OS/2 1.1) and as a concurrent LAN Manager
2.0 server (using the HPFS386 file system and Microsoft OS/2 1.21).
This article assumes you are starting with a machine capable of
running as either type of server, and that the hard drive is at least
40 MB in size or larger.  Also, this article assumes that you do not
currently have any partitions defined on the hard drive.


Installing Both Versions of OS/2

1.  Begin installing OS/2 1.21 on the hard drive.

2.  If the disk has been partitioned previously, press Esc to exit the
Install Program.  Execute the command FDISK /D.  Then reboot the computer
using the install diskette.

3.  When you are prompted either to accept the default hard disk partition or
to select your own, select your own.  The default configuration would allocate
all of the hard drive to the OS/2 1.21 partition.  Your own needs will
determine how much space to allocate to each operating system.  3Com
recommends allocating approximately half of the disk space to each.

4.  At the end of the OS/2 1.21 installation, when you are instructed to
remove the Installation diskette and press Ctrl-Alt-Del to reboot from the
hard drive, remove the OS/2 1.21 Installation diskette.  The installation
of OS/2 1.21 is complete.

5.  Insert the 3Com Server Adapted OS/2 1.1 Installation diskette, then press
Ctrl-Alt-Del.

6.  When the Install Program for OS/2 1.1 asks if you wish to
repartition your hard disk by running FDISK, type Y to specify your own
partitions.

7.  When running FDISK, create a primary OS/2 partition.  Allow
FDISK to create this partition at the maximum size.  This will allocate the
disk space not used by OS/2 1.21.

Note:  When you create a partition, FDISK will automatically make the newly
created partition the Active partition (only one partition per hard drive is
allowed to be Active at a time).

8. Select option 2 from the FDISK menu, Change the Active Partition.
Make partition 1 (which displays as type non-DOS) the new active
partition. Exit FDISK and reboot (with the 3Com server adapted OS/2
1.1 Installation diskette still in drive A:).

Note:  This is only true for 3Com's server adapted OS/2 1.1.  Other
versions of OS/2 1.1 require that C, the OS/2 1.1 partition, be active in
order for OS/2 to be installed.

The 3Com server-adapted OS/2 Install Program does not correctly
check that drive C is Active; it only verifies that partition 1 is
the active partition. If partition 1 is not active, the Install
Program will not copy files to drive C.

9.  Go back through the 3Com server adapted OS/2 1.1 Install Program,
selecting a mouse, a printer, a printer port, and the Protected
Mode Shell.  When asked if you wish for the Install Program to format
drive C:, type Y.

10.  When prompted by the Install Program, press Ctrl-Alt-Del to
reboot the system.  Once again, select a mouse, a printer, a printer
port, and the Protected Mode Shell.  This time do not allow the
Install Program to format drive C:.

The Install Program will now copy approximately 44 files to your
drive C:; just enough to successfully boot OS/2 from that hard
drive to the point where it can then begin installing the remainder
of 3Com server adapted OS/2 1.1.

FOR 3COM'S SERVER-ADAPTED OS/2 1.1 ONLY:

11a.  When the "Continuing with Install" panel is displayed and you
      are instructed to remove the Installation diskette from drive A:
      and to press Ctrl-Alt-Del to reboot, DO NOT REMOVE THE
      INSTALLATION DISKETTE. Press Ctrl-Alt-Del.

11b.  When the initial panel of the 3Com server adapted OS/2 Install
      Program appears, press Escape to exit the Install Program.  Enter
      FDISK and select option 2, Change the Active Partition, from the
      FDISK menu. Exit FDISK. Remove the 3Com server adapted OS/2
      Installation diskette from drive A: and press Ctrl-Alt-Del to
      reboot.

FOR OTHER VERSIONS OF OS/2 1.1:

11.  Remove the diskette and reboot as prompted.  Then continue
     installation by inserting the OS/2 Diskette 1 into drive A.


12.  When prompted by the Install Program (now executing from the
hard drive), complete the installation of OS/2 1.1.


Switching Between the Versions of OS/2

Once you have both versions of OS/2 installed, you can easily switch
between them by following these steps:

1.  Use OS/2 1.1 FDISK and OS/2 1.21 FDISKPM to make one of the partitions
the Active partition (FDISKPM calls them Startable and Not Startable).

2.  Shut down OS/2 from the Task Manager.

3.  Reboot the server.
