[Ham-Computers] RE: Virtual PC 2007

[Hsu, Aaron (NBC Universal)]

*** WARNING:  This reply is quite long ***

Creating a bootable USB key is not difficult and there are now several on-line sources that show you how to do it.  There are also apps available that will do it for you.  If you're technically inclined, here are the basic steps on how I've done it for the past few years...

(BTW, this creates USB key that emulates a partitioned hard drive)

"Stuff" needed:

- One bootable DOS floppy with the DOS of your choosing (Win98SE's DOS is the best choice...make sure you have a valid license!).  FreeDOS is an alternative.  This disk will need the FDISK and FORMAT utils (at a minimum).  

- One USB key (any size > 1MB).  Save anything you need as this process will re-format the device.

- One computer that supports booting from a USB HD.


OK, now that you have "everything", do the following:

1.  Shutdown your PC.

2.  Insert the USB key into a *NATIVE* USB port.  It must be a port managed by the PC's on-board chipset - don't plug it into a hub.

3.  Insert the bootable floppy into the floppy drive

4.  Start the system and enter your PC's BIOS/CMOS setup.

5.  Find the section that allows you to turn on "legacy" mode for the USB ports.  Often, this is labeled as "USB Keyboard" and "USB Mouse" support.  What this does is to allow the PC to supply +5v to the USB port even when the computer is off.

6.  Check to see if your BIOS supports booting from a USB HDD.  If so, change the boot order so that the USB HDD comes before the first hard drive.  Also make sure the system is configured to boot from your floppy drive before the HDD or USB key.

7.  Save the changes, exit the BIOS/CMOS setup, and reboot.

8.  You still have the DOS floppy in the floppy drive, right?  If so, the system should have booted to the floppy.

9.  At the DOS prompt, start FDISK.

10. When asked about "Large disk support", say "Yes".

11. Press "5" to change the current drive.  Select the drive that matches the size of your USB key.  BTW, if you have an older version of FDISK, it may not report drive sizes >32GB properly, so be careful which drive you select.  If in doubt, shutdown and disconnect your hard drives first!)

12. Press "3" to delete any existing partitions on the key.  If it had an "extended" partition, you'll need to delete the "Logical" partitions first.

13. Press "1" to create a new partition.

14. Press "1" to create a "Primary" partition.

15. Answer "Yes" if you wish to use the full size of the drive for the Primary partition.

16. When the Primary partition is created, FDISK should take you back to the main menu.  Press "2" to make sure the Primary partition is marked as "Active"...only "Active" partitions are bootable.

17. If you're happy with the partitioning, press [ESC] to save the settings and exit FDISK.  If you made changes, you'll get a warning that you need to reboot before DOS will recognize the change.

18. Once back to a DOS prompt, give the 3-finger salute (CTRL-ALT-DEL) to reboot the system.

19. You did set the floppy drive as the first boot drive, right?  If so, you should be back at a DOS prompt after reboot.  If the USB key was set higher in priority for booting, then you might get an "Invalid boot sector", "Invalid disk", or "Missing operating system" type message.  If so, then go back into the BIOS/CMOS setup and change the boot order.

20. If the partitioning went as expected, you can now format the USB key as you would a hard drive.  Type "FORMAT C: /S" to format the USB Key and install the boot files.

21. Once the format is complete, the only thing left is to test it!  Eject the floppy and re-boot the computer.

Assuming the PC is able to boot from USB Keys (emulating a USB-HDD), the system should now boot from the USB Key.  Some BIOS' don't support booting from USB Keys even if they're emulating a USB HDD.  If this is the case, you may need to format the USB Key as a "RAW" device, which is acutally not easy.  Even then, the system may not boot from it.  It basically comes down to how well your BIOS supports booting from a USB Key.

That's it!  If you have a working, bootable USB Key, you can now go back into whatever OS you normally boot into (such as Windows or Linux) and copy the rest of the DOS files to the key (put them in a directory called "DOS" and make sure to add C:\DOS to the path in AUTOEXEC.BAT).  What DOS files am I talking about?  DEBUG, CHOICE, EDIT, HIMEM, EMM386, SETVER, MEM, etc.  Those who remember using DOS will know what I'm talking about.  Once you have the key the way you want it, BACK IT UP!  If you use a drive cloning utility (such as GHOST), you'll also be able to restore the boot sector and partition table should the key be damaged.  You'll also be able to make additional copies of the USB key.

Treat the USB key as you would a regular hard disk and use it the same way.  You can install and run programs just as you did before.  However, don't run anything that resets the USB bus or controller.  Doing so with lock the DOS session as it's running on the USB bus and won't tolerate a bus reset.

Oh, and one thing to keep in mind...I've found that you generally can't have more than one emulated USB device on a system.  For example, if you have both a USB key and another USB drive installed, the system might not boot properly from the USB key.  I've seen the same thing happen if you have a USB floppy drive and a USB Key.  If this is your situation (USB floppy and key), you might not be able to build the USB key with these instructions.


Now, which is better, a USB key or a Virtual session?  If you want a "pure" DOS environment with full access to every peripherial connected to your computer (within the limits of DOS), then the USB key the best way to go.  If you want to build an environment that tolerates "screw ups" and doesn't need access to "real" components, then a Virtual Session is the better way to go.  What do I mean by "screw ups"?  In a virtual session, you have the option of saving "Undo" files.  If you did something to "screw up" the session, just end the session and delete the "undo" file (aka, don't merge the changes).  When you restart the virtual session, it will boot back to where you where before your last boot.

Anyways, this post is getting *waaaaaay* long (I'm from So. Cal...I'm allowed to say *waaaay*).  If anyone has any questions about this or if I missed a step, please let me know.

73 and l8r dudez,

  - Aaron, NN6O


-----Original Message-----
Sent: Thursday, March 15, 2007 2:43 PM
Subject: [Ham-Computers] Virtual PC 2007

Off and on for a year or so I have been wondering whether or not the use of a USB thumb drive could be used to create a bootable (and portable) fully functional DOS inside of Windows XP-Home.  Many of us remember that W98SE may have been the last OS that allowed a full restart in the DOS mode.  In Win98SE you could do Start/Programs and get to a DOS prompt that permitted some, but not all, the DOS functionality.

Is Virtual PC 2007 just one step better than that?

Any ideas on how, most easily to proceed?

John W0IKT