Sunday, February 27, 2011

Older computers that can't boot from usb - The howto guide

Before the actual technique, some details...

Most of the older computers cant boot from usb (pen drives or memory cards, ext hdd) because of the bios (basic input output system) limitations. This is because the older bios do not contain the usb drivers. So at the time of booting the usb drives are not recognized.

Generally, drivers are automatically loaded during boot process from 4 sources -
From bios itself
From addon cards or daughter cards (if additional bios is present)
From system disk or hard disk where we additionally install it after os installation
From os itself (win 7 itself has most of drivers)

If any device attached to computer requires driver, which is not present, will not work properly
So in this case the usb device do not get drivers from old bios and if you have to boot it then you have to provide it all the required usb drivers from some other source.

The easy and simple method to do this is to use the plop boot cd which contains required usb drivers for boot process to complete.

The technique -
Download  from

Extract it to get the iso file plpbt.iso (can extract using 7zip )
Then burn iso file using any cd/dvd burning software like nero. This will be a bootable cd.

Now attach the usb device (containing any kind of  os for installation purpose or live environment) to the usb port of the computer (that doesn't support usb booting) and then boot it  from cd you just created.

Nearly every older pc bios contains cd drivers so cd booting in older pc is not a problem.

After booting from cd you will get a screen that shows the plop boot manager.
Then you will get a menu that has some options to choose from. There you have to choose the usb option.
When you select the usb option there, the usb drivers will be automatically loaded for bios and the usb device will get detected by bios. After that the usb device will start booting. then you can eject the tray and take out the cd. This will not effect the usb boot process.

The plop boot manager do not permanently change or modify the bios. It is a temporary process. That means in future if you have to boot from usb  device again then you have to repeat the whole process.

If the usb device do not boot with this process the check the device itself. May be the pendrive itself is not bootable or there something wrong in the os that is inside the usb.
In that case again prepare your pendrive properly and try again.

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