Sunday, August 21, 2011

Booting from a CD or DVD

Howto: Configure a PC to boot from an external CD or DVD

Update:  This article may not apply if you have a newer Laptop with a UEFI hard disk, running Windows 8.x or 10.x.  See this article for more information about UEFI
Keyliner - Virus Cleanup Steps



The question arose: Can a Netbook PC boot from an external USB CD/DVD drive, even if the device does not have a built-in drive? Yes. This article describes the how to boot any PC from a DVD and the why of doing this.

Why do this? In a previous Keyliner article, "Microsoft System Sweeper - Bootable from a CD", I described a new Microsoft product that allows you to boot an infected PC from a CD and run a reasonably good virus scanner. Other situations might include booting a PC from a Windows PE Boot disk or a Linux boot disk in order to retrieve data from a corrupted hard drive. Finally, you might have a backup program, such as Acronis, which can boot from a CD in order to recover a system backup. In each of these instances, the CD/DVD must be a bootable CD and typically, the CD is produced by the vendor.


Booting from CD on a Normal PC

When a PC boots, it typically looks to the Hard Disk as the first boot device but you may get lucky and it might be configured to look at the CD first.

Confirm this by inserting the Bootable CD/DVD. Shutdown the computer normally and cold boot. If you see a DOS-like prompt, "Press any key to boot from the CD", then you are all set and this article will not be of interest. But a lot of machines ignore the CD and boot directly from the hard disk.

But wait! On some machines, as they boot, you may see a "F10=Boot Menu" (usually, this prompt is right below the F2=Setup). If you see this prompt, quickly press F10 a couple of times. A short menu will display. Arrow-key away from the "Hard Disk" choice and choose the CD/DVD drive and press Enter. The CD will boot and once again, you are lucky and you can ignore the rest of this article.


If the CD is still ignored (or you do not have a F10-BootMenu), and the regular operating system loads, then follow these basic steps to re-configure your BIOS. This is a low-risk, one-time setup and once set, you can leave the changes in place.


Configure the BIOS to Boot from CD

Follow these steps if your PC does not boot from a CD (tested, above).

Computer manufacturers vary with different BIOSes and, unfortunately, they have slightly different steps for entering the BIOS configuration screens. However, these basic steps will work for most desktop and laptop computers with built-in CD/DVD drives. See below for Netbook-specific instructions when there is not a built-in CD/DVD drive.

1. From the operating system (Windows) desktop, shut-down the computer normally.

2. From a powered-off state, power up the computer and watch the screen for the hardware's BIOS splash screen. You may see the computer's brand name (Dell, HP) or a generic BIOS name, such as Phoenix or AMD. The splash displays just before the operating system boots and the screen only displays for two or three seconds.

3. Reading the BIOS splash-screen, look for "SETUP" mode.

On most machines, it will show "F2=Setup" (sometimes, on older computers, F10 or Esc.).

Tap the F2 key a couple of times. Press the key while the BIOS splash-screen is displayed -- you have to be quick. Press the key two or three times*.
If you miss, the operating system will boot normally; return to step 1 and try again.

4. The BIOS Setup screen is a DOS-like character screen and the mouse will not work.

Usually, along the top is a menu. Arrow-key across, looking for a BOOT menu. On some BIOS, look for the SYSTEM menu and you will find a BOOT ORDER menu within.

5. In the Boot Menu will be a list of devices. For example:

+Hard Disk
Removable Devices
USB Storage Devices
CD/DVD/CDR-DVDR

Arrow-key down, highlighting the CD drive.

The goal is to move the CD-choice to the top of the list. Naturally, BIOS manufacturers vary on how to do this. Phoenix BIOS, for example, uses F6 to Move/Shift the value up in the list. Other BIOSes use Page-Up/Down or +/-. Look at the bottom or right side of the screen for instructions.

Using the correct keystroke, move the CD/DVD drive to the top of the list, above the hard disk.

6. Referring again to the keyboard guide, press the appropriate key to Save the changes. On most BIOSes, this is F10=Save.

7. Allow the PC to reboot, with a Bootable CD in the drive.

Watch the screen carefully and act quickly.

On some BIOSes, if you see a "F10=Boot Menu", press F10 a couple of times and choose the CD/DVD drive. The PC should boot from the CD.

On other BIOSes, a menu is not prompted or displayed. Instead, the PC will ask "Press any key to boot from CD". Press the Space-bar or "Y" to be safe (the Shift, control or Alt keys will not work). The PC should boot from the CD.



Booting from a CD using a Netbook Computer

Netbook computers do not have CD/DVD's to boot from. You will have to buy an external USB CDR/DVD drive. These typically cost around $50 and can be used on any computer as a CD/DVD drive. Any brand will do.

Because Netbooks never come with a CD/DVD, you will have to go into the BIOS to configure them. Following the steps above, cold-boot the computer and look for the BIOS setup screen.

1. Plug in the External CD/DVD into any available USB port.

No software drivers or other setup is required.

2. In the BIOS setup screens, locate the BOOT menu.

3. In the menu, shift the devices to be in this order (see above, for exact steps)

USB Storage Device
Removable Device
+Hard Disk
(other devices)

where USB Storage and Removable are at the top of the list.

4. Press (F10=Save) to save the BIOS changes.

5. Allow the PC to reboot.

6. With the DELL MINI Netbook, the splash-screen displays "F10=Boot Menu". Press F10.

7. Oddly, from the displayed menu, choose "CD/DVD" (not USB or Removable Devices, even though you configured the BIOS to be this way). The CD should boot. When prompted, type "Y" to confirm.


*On older computers, the F2=Setup key may not work if you have a USB keyboard plugged in. The BIOS does not load the keyboard driver in time for the splash screen. In these cases, you will have to plug in an old-style PS/2 DIN keyboard into the "purple" keyboard plug.

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