boot from "USB Device"

  • Thread starter Thread starter Timothy Daniels
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Timothy Daniels

Virtually all of Dell's current PCs include "USB Device"
as a bootable device type in their BIOSs' Boot Sequence
of device types. Here is the setup specs for Dell's XPS 420
desktop:
http://support.dell.com/support/edocs/systems/xps420/en/OM/HTML/appendix.htm#wp1054035

Check out the Option Settings under the "Boot Sequence"
section. It refers to "USB Device" as a "memory device",
not a "storage device". And when I explicitly asked Dell's
Tech Support whether that would include USB hard drives,
the answer was "No". Would someone here tell why the
Dell PCs can boot from USB flash drives and not from
USB hard drives?

*TimDaniels*
 
Virtually all of Dell's current PCs include "USB Device"
as a bootable device type in their BIOSs' Boot Sequence
of device types. Here is the setup specs for Dell's XPS 420
desktop:
http://support.dell.com/support/edocs/systems/xps420/en/OM/HTML/appendix.htm#wp1054035

Check out the Option Settings under the "Boot Sequence"
section. It refers to "USB Device" as a "memory device",
not a "storage device". And when I explicitly asked Dell's
Tech Support whether that would include USB hard drives,
the answer was "No". Would someone here tell why the
Dell PCs can boot from USB flash drives and not from
USB hard drives?

*TimDaniels*
Click to expand...

Could it be that the drive has to be formatted as a "super floppy", ie
no partition table, just a boot sector?

Try Fdisk-ing and reformating your flash drive. I suspect it will fail
to boot after you do this.

- Franc Zabkar
 
Could it be that the drive has to be formatted as a "super floppy", ie
no partition table, just a boot sector?
Click to expand...
Try Fdisk-ing and reformating your flash drive. I suspect it will fail
to boot after you do this.
Click to expand...

Probably. Apart from that, USB disk and USB flash uses the
same command set, i.e. if one is bootable, then so is the other.

Arno
 
As I stated earlier, it all depends on the drivers one finds on the USB boot
medium. A USB floppy boots OK because the BIOS knows how to handle it. A USB
stick or hard drive will only boot OK if it has the right drivers for the right
operating system on the boot medium in addition to the boot sector and and
whatever OS files are needed... Ben Myers
 
Ben Myers said:
As I stated earlier, it all depends on the drivers one finds on the USB
boot
medium. A USB floppy boots OK because the BIOS knows how to handle it.
A USB
stick or hard drive will only boot OK if it has the right drivers for the
right
operating system on the boot medium in addition to the boot sector and and
whatever OS files are needed... Ben Myers
Click to expand...


The only way I manually was able to get a USB flash drive to become bootable
w/o using a utility was to partition/format it as a FAT16 partition and then
sys the flash drive being sure to include msdos.sys.

Worked like a charm.

I have not make extreme attempts to make an external HDD bootable, but would
like to do so if I had the time.....


Stew
 
A boot floppy is assigned BIOS unit 00h, and hard disk (partitionable) is unit 80h.
These numbers are coded into the MBR (80) and OS boot sector (00 or 80).
To find out which, boot DOS from non-USB and check the drive is assigned A/B or C+.
If Dell has USB floppy support, it will not work if the disk has an MBR.

Also, there are at least three classes of USB storage device,
and the BIOS probably only implements some of them (floppy most common).
 
S.Lewis said:
The only way I manually was able to get a USB flash drive
to become bootable w/o using a utility was to partition/format
it as a FAT16 partition and then sys the flash drive being sure
to include msdos.sys.

Worked like a charm.
Click to expand...


What does it mean to "sys the flash drive"?

*TimDaniels*
 
Rod Speed said:
The sys dos command puts the basic dos boot files on the drive.
Click to expand...


Yep. And the way I did it was kind of clumsy. I actually had to disable all
other bootable drives/network in BIOS, then boot to a modified Win95 floppy.

Under those conditions, the system recognized the flash drive volume (256mb)
just as it would a fixed drive. FDISK, format, sys.

Not positive, but I believe I then re-enabled all the other drives in BIOS,
but could still choose to F12 and boot from the flash drive. (Dimension
8300)
 
It is easier to get bootpart and run it under 2K/XP to build a DOS boot sector.

Beside the other reasons I gave for USB boot being difficult,
the CHS geometry in the MBR and boot sector have to match those of the BIOS,
which is not likely on most USB flash devices I've looked at.
 
Eric Gisin said:
It is easier to get bootpart and run it under 2K/XP to build a DOS boot
sector.

Beside the other reasons I gave for USB boot being difficult,
the CHS geometry in the MBR and boot sector have to match those of the
BIOS,
which is not likely on most USB flash devices I've looked at.
Click to expand...

Could you please explain further why Canadian flash devices are unlikely to
have a cheese geometry in their moobers which match those in their
biospheres? And I have a nice pair of Canadian boots which aren't in the
least bit difficult.
 
Taken said:
Could you please explain further why Canadian flash devices are unlikely to
have a cheese geometry in their moobers which match those in their
biospheres? And I have a nice pair of Canadian boots which aren't in the
least bit difficult.
Click to expand...

I give up! This thread has evolved (drifted?) completely beyond my ken.
 
Eric Gisin wrote in news:[email protected]
It is easier to get bootpart and run it under 2K/XP to build a DOS boot
sector.

Beside the other reasons I gave for USB boot being difficult,
the CHS geometry in the MBR and boot sector have to match those of the BIOS,
which is not likely on most USB flash devices I've looked at.
Click to expand...

How much easier can it get when the SYS command takes care of all that.
 
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