Operating system not found, or was it?

VanguardLH wrote:
micky wrote:

Boot configuration data store could not be opened. Access is denied.

Since bcdedit.exe is a console-mode program, did you load the command
shell (cmd.exe) with elevated (admin) privileges? You may have to log
into an adminstrator-level account in Windows to elevate the command
shell. Even then, if UAC is enabled then you have to OK the prompt to
allow access.

You've just made my point. :-) Bah, humbug.

In message , VanguardLH
writes:
[]
I've had drives where the bearings went bad. As long as the device was
warm, like for a reboot or soon after using it previously, the drive
would spin up. When cold, the bearing friction was more than the motor
could handle to spin up the platters.
[]
to get the drive to spin up. After running for awhile, I noticed the
HDD was hot (back then I just used my hand since I didn't have software
monitoring the drive's temperature). Almost burned my fingers on the
HDD when I touched it. Could've fried eggs on it. Yep, I found the
[]
Note that SMART will not directly tell you a spindle is siezing or a
bearing is too worn. It will report the drive's temperature, though.
[]
In the set of SMART parameters he posted earlier in this thread, it was
57°C, IIRR. This seemed a little high to me - I normally expect a drive
to be in the thirties - and thus a possible cause for concern, though
I'm a bit paranoid; it's not _that_ high. (But we don't know how long
he'd had the system on, or what he'd been doing, or the room
temperature.)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Science isn't about being right every time, or even most of the time. It is
about being more right over time and fixing what it got wrong.
- Scott Adams, 2015-2-2

In message , VanguardLH
writes:
micky wrote:
[snip]

Long section snipped, in which VLH very much _seemed_ to be saying micky
(and by extension I) should be using IMAP rather than POP.

It came over very much like the arguments that we should accept Windows
10 rather than 7 (or XP).

Now before you set about demolishing that, I know it's not the same, or
- to some extent - even a _good_ parallel. But the basic principle
applies: some of us like, and are happy with, older systems (micky and I
prefer POP to IMAP, VLH [and I!] prefer W7 to W10), and are a _bit_
tired when someone won't stop trying to persuade us to change.

But then:

15. Because of some of the differences I don't want IMAP.

IMAP has more. If you are happy less then stay with less.

VLH says he will "let" us stay with POP! (Though the nag is still there
with the use of the word "less".)

I had a car that was 24 years old. Didn't need to buy a new car to get
new features because I could forego them or adapt the old car to get
some of the new features. I only got rid of the old car when it cost
far too much in some major repairs. I still have another car that is 17
years old. I added a new car because I did want some of its new
features that would've been too expensive to add or unavailable to the
old car. As you notice from the name of this newsgroup, I'm also still
using Windows 7.

I too prefer old cars for simplicity, though (probably because rust is
maybe more of a problem in England than some parts of the USA) they tend
not to be as old as yours. I recently had to change - despite the last
tankful returning 62 mpg - due to rust (I'd have paid for it to be fixed
but was told by more than one source that once it's started it will cost
that much every year). I didn't want a turbo but couldn't find one
without; the "new" car doesn't have the low-revs power the old one did,
though I'm sure it's more powerful altogether. (And an example of
sophistication causing problems I know you VLH will smile at: I'd let
the new one's battery run low enough that it wouldn't quite start. No
problem - I have a battery to jump start it. Just get the jump leads ...
oh. Opening the tailgate isn't any more just turning a handle: there's a
button under the handle which operates a solenoid to unlock - which of
course didn't, with the low battery. Fortunately I could get into the
luggage area from the back seat by moving the parcel shelf, though it
was awkward.)
[]
Why define rules to send duplicates of your sent messages
when IMAP does that without using rules?

Because you pay a price for having them do that automatically. For one
thing, I only want it done when I'm out of town, not all the time.
Which is is usually about 3 weeks out of 52.

Oh, more criteria that was not divulged BEFORE my reply (which was to

He had, quite early in the thread, explained he was on one of his
infrequent travels - that's why he is using the laptop, whose occasional
inability to find the OS is what started the thread.

Gilliver, not you).

My name's John, by the way.
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Science isn't about being right every time, or even most of the time. It is
about being more right over time and fixing what it got wrong.
- Scott Adams, 2015-2-2

micky wrote:

In alt.windows7.general, on Sat, 02 Mar 2019 18:17:15 -0500, Paul
wrote:
It could be an issue with the MBR sector or an issue
with the System Reserved partition, as much as C: itself.

And the System Reserved partition isn't normally visible,

Can't I assign it a partition letter and make it visible?

Yes.

*******

If a partition is type 0x07, it's visible. If it's
visible, you can assign a drive letter.

If you assign a drive letter, the partition will be
given a System Volume Information.

If System Protection is then enabled, every time you make
a Restore Point (like, during a driver install), if that
drive letter is enabled for System Protection, data is
put in the SVI folder. This can continue until the tiny
partition is full.

This is one reason why the partition has no drive letter.

*******

If a partition is type 0x27, it is "hidden". That means it
has a label (of sorts) in Disk Management. It isn't entirely
hidden. But, you cannot examine the files on it. And you
definitely cannot assign a drive letter. It's in a sense,
protected at two levels from "accidentally putting on weight".

*******

CHKDSK only works for mountable volumes. This means
that extra measures would be required for hidden stuff,
or perhaps even assigning a drive letter makes more sense.
In this picture, I'm using BCDEDIT to dump some GUIDs (none
of which worked). As well, the "mountvol" command gives some
info, on the left of the picture.

https://i.postimg.cc/DZR5YwPb/chkdsk...le-volumes.gif

*******

PTEDIT32 can edit the partition table, and can be used to change
a partition from 0x27 invisible to 0x07 visible. You can even do
that from a Win7 x32 install DVD used to reach a command prompt
window, then start PTEDIT32 from there. The WinPE environment has
support for a small amount of your GUI based tools.

Get yourself a copy of PTEDIT32. Use "Run as Administrator" or
it will throw "error 5". The installer DVD command prompt is already
running as administrator.

http://www.download3k.com/System-Uti...ion-Magic.html

enpm800retaildemo.zip 23,776,770 bytes

You can use 7ZIP to burrow into the file and extract
the copy of PTEDIT32.exe.

L:\enpm800retaildemo.zip\Setup\PMagic.cab\
PTEDIT32.EXE 503,808 bytes September 16, 2002, 2:24:48 AM

In 7ZIP, you have to drill into the CAB to extract the file.
The file is "free", in that no license key is used with the
utility. The main program on the other hand, is a licensed
product. Trial versions only run for so long. PTEDIT32
will run forever. PTEDIT32 used to be on a Symantec FTP
server for the last ten years, but they cleaned off their
server, requiring us to "bob for apples".

C:\Downloads\enpm800retaildemo.zip\Setup\PMagic.ca b\

PTEDIT32.exe 503,808 bytes

*******

OK, now let's play with our new tool.

https://i.postimg.cc/CLg9Fcbn/needs-editing.gif

You can actually use a Windows Installer DVD (in my case the x32
one worked), to run PTEDIT32 using the Command Prompt on the
Troubleshooting section of the installer DVD. This is
testing with two different setups. The second picture
has partition types of 0x07 so no edit and Save changes
is required. I suspect the reason a x32 Win7 DVD is required,
is because the PTEDIT32 code is actually "16 bit era".

https://i.postimg.cc/8CyBYmVY/needs-editing-2.gif

https://i.postimg.cc/q7d72zDZ/edit-not-needed.gif

*******

Anyway, you're right, assign a drive letter to it and
CHKDSK. Make sure in the System control panel that
System Protection on that drive letter is turned off.
I haven't tried removing a drive letter, so I don't
know how hard that part is. Presumably the drive letter
"lives" in the mountvol section of the registry. There
is a program named mountvol.exe that reads out that
part of the registry, as well as a mountvol section
of the registry.

Paul

J. P. Gilliver (John) wrote:

In message , VanguardLH
writes:
[]
I've had drives where the bearings went bad. As long as the device was
warm, like for a reboot or soon after using it previously, the drive
would spin up. When cold, the bearing friction was more than the motor
could handle to spin up the platters.
[]
to get the drive to spin up. After running for awhile, I noticed the
HDD was hot (back then I just used my hand since I didn't have software
monitoring the drive's temperature). Almost burned my fingers on the
HDD when I touched it. Could've fried eggs on it. Yep, I found the
[]
Note that SMART will not directly tell you a spindle is siezing or a
bearing is too worn. It will report the drive's temperature, though.
[]
In the set of SMART parameters he posted earlier in this thread, it was
57°C, IIRR. This seemed a little high to me - I normally expect a drive
to be in the thirties - and thus a possible cause for concern, though
I'm a bit paranoid; it's not _that_ high. (But we don't know how long
he'd had the system on, or what he'd been doing, or the room
temperature.)

Yep, 57 C is too high; however, in the SMART report that micky published
here, the temperature was 50 C when he ran the report. 50 C -- if that
was the maximum temperature the HDD ever experienced -- is okay, but we
don't know the temperature history of his HDD.

Most HDDs are rated from +5 to +55 C. Some go up to +60 C (I think the
WDCs go that high) for their operating temperature range. My HDDs
usually run around 39 C, but may occasionally jump to 46 C under heavy
use. None of my HDDs have a fan by them for cooling; for example, I
have no fan at the front of the case to blow over the drive cage. Just
the air drawn from the front and everywhere else by the backside case
fan and GPU fan to push air out of the case.

A lower room temperature would mean a higher temperature differential
between the incoming air (provided it is not pre-heated by other
components) and the heat generated by the drives. However, I doubt the
OP is wearing a snowmobile suit while using his computer. I've had to
work in computer rooms where on one side of the mainframe the
temperature was okay but you left a winter coat with hood at work for
when you went to the other side of the mainframe which has the A/C
blowing down and it was frigid on that side.

Also, the temperature that micky reported in his SMART report was only
at the time that he ran the SMART tool to get the attributes and their
values. SMART does not record the peak temperature ever experienced by
the drive. SMART also doesn't record a history, so we don't know if 50
C was a short-lived peak temperature or not the highest the drive has
sustained for more than a few minutes.

A good disk monitor should not only report what are the current SMART
values, like temperature, but also record a history of past temperatures
for the HDD. The one I use has a temperature history that shows the
current temperature measured at 10-minute intervals over the past 4
hours, the daily average, daily maximum, and daily minimum over the
prior 6 months. That provides a view of what the drive has experienced,
not just what is experienced now.

Like micky, I also have the Speccy tool that will report the current
SMART values. It has no history of those values. I use HD Sentinel
Pro; however, I think the free Standard version will report history.

https://www.hdsentinel.com/store.php

Hmm, can't tell at what version it will record temperature history. The
trial look to not expire but is also missing so many functions that it
probably doesn't monitor and record the temperature. My guess that is
part of the "Monitor Windows disk-related events/errors" feature which
is only available in the Professional and Enterprise editions, not in
the trial and Standard editions. There might be other free disk
monitors that will record the drive temperature history. I remember
trying several (don't remember what they were) and eventually gave up on
the freeware and went to payware for a decent disk health monitor. I do
remember Open Hardware Monitor (https://openhardwaremonitor.org/) but it
doesn't look to record any history, just report what SMART currently
reports. Active@ Hard Disk Monitor has temperature history but it is
more expensive payware ($20 more than HD Sentinel). I also use Speedfan
(to control fan speeds since the CPU fan won't let the BIOS control it -
damaged part on mobo) and it has a history of temperatures (CPU, CPU,
case, drives); however, it doesn't retain a history beyond when it got
loaded (at Windows boot), and then the user has to enable its charting,
and it won't retain a history beyond 4 hours.

In message , VanguardLH
writes:
J. P. Gilliver (John) wrote:
[]
In the set of SMART parameters he posted earlier in this thread, it was
57°C, IIRR. This seemed a little high to me - I normally expect a drive
to be in the thirties - and thus a possible cause for concern, though
I'm a bit paranoid; it's not _that_ high. (But we don't know how long
he'd had the system on, or what he'd been doing, or the room
temperature.)

Yep, 57 C is too high; however, in the SMART report that micky published
here, the temperature was 50 C when he ran the report. 50 C -- if that

OK, I may have remembered the 57 wrong, or he may have mentioned it
somewhere else.

was the maximum temperature the HDD ever experienced -- is okay, but we
don't know the temperature history of his HDD.
[]
Also, the temperature that micky reported in his SMART report was only
at the time that he ran the SMART tool to get the attributes and their
values. SMART does not record the peak temperature ever experienced by
the drive. SMART also doesn't record a history, so we don't know if 50
C was a short-lived peak temperature or not the highest the drive has
sustained for more than a few minutes.

I said much the same thing.

A good disk monitor should not only report what are the current SMART
values, like temperature, but also record a history of past temperatures
for the HDD. The one I use has a temperature history that shows the
current temperature measured at 10-minute intervals over the past 4
hours, the daily average, daily maximum, and daily minimum over the
prior 6 months. That provides a view of what the drive has experienced,
not just what is experienced now.

Like micky, I also have the Speccy tool that will report the current
SMART values. It has no history of those values. I use HD Sentinel
Pro; however, I think the free Standard version will report history.

https://www.hdsentinel.com/store.php

For SMART, I use DiskCheckup from PassMark
(https://www.passmark.com/products/diskcheckup.htm); it saves the
parameters when you run it. I've just checked, and that includes
temperatu since I've had the drive, it's recorded values ranging from
22 to 41, with all but five of them (22, 26, 40, 41, 40) being 3x.
[]
the trial and Standard editions. There might be other free disk
monitors that will record the drive temperature history. I remember
trying several (don't remember what they were) and eventually gave up on
the freeware and went to payware for a decent disk health monitor. I do
[]
I don't have anything like that. I haven't used it for a while - let me
just fire it up - but I do have speedfan; though as the name suggests it
can be used to control fans in some systems, I use it just as a way to
look at the temperature sensors it can find (only four in this laptop,
which it calls HD0, Temp1, Core O, and Core 1). I don't _think_ it has
any long-term logging capability, but it will draw a chart from when you
start it. http://www.almico.com/speedfan.php
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

science is not intended to be foolproof. Science is about crawling toward the
truth over time. - Scott Adams, 2015-2-2

In alt.windows7.general, on Sat, 2 Mar 2019 23:59:44 -0600, VanguardLH
wrote:

micky wrote:

Boot configuration data store could not be opened. Access is denied.

Since bcdedit.exe is a console-mode program, did you load the command
shell (cmd.exe) with elevated (admin) privileges? You may have to log
into an adminstrator-level account in Windows to elevate the command
shell. Even then, if UAC is enabled then you have to OK the prompt to
allow access.

Well, it turns out I was right: Now that you explained how to use
bcdedit, and I see the results, I think Paul still thinks I have a
second OS on my laptop. I hope this will convince him I don't. ;-)

But you folks were righter, as you'll see after the bcdedit results.

Windows Boot Manager
--------------------
identifier {bootmgr}
device partition=\Device\HarddiskVolume1
description Windows Boot Manager
locale en-US
inherit {globalsettings}
default {current}
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
displayorder {current}
toolsdisplayorder {memdiag}
timeout 30

Windows Boot Loader
-------------------
identifier {current}
device partition=C:
path \Windows\system32\winload.exe
description Windows 7
locale en-US
inherit {bootloadersettings}
recoverysequence {a0a822b1-5076-11e7-a12c-ed5588230eb9}
recoveryenabled Yes
osdevice partition=C:
systemroot \Windows
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
nx OptIn

So I don't have a second operating system.

HOWEVER, I unplugged the flash drive from the USB hub, and since then it
has booted 4 times without complaining that the OS can't be found.

I forget how to get into the BIOS, so I can't check this, but I guess
the problem is that I put the USB port ahead of the HDD in the boot
order. I thought it was supposed to check for an OS and if there wasn't
one, go to the next device. Instead it says "OS not found".

OTOH, having the mouse, the cell phone, and the speakers plugged into
the hub never causes a problem.

So the flash drive was the problem, even though though it had nothing
but data files and one set of program files.

Thanks all for your help.

micky wrote:
In alt.windows7.general, on Sat, 2 Mar 2019 23:59:44 -0600, VanguardLH
wrote:

micky wrote:

Boot configuration data store could not be opened. Access is denied.
Since bcdedit.exe is a console-mode program, did you load the command
shell (cmd.exe) with elevated (admin) privileges? You may have to log
into an adminstrator-level account in Windows to elevate the command
shell. Even then, if UAC is enabled then you have to OK the prompt to
allow access.

Well, it turns out I was right: Now that you explained how to use
bcdedit, and I see the results, I think Paul still thinks I have a
second OS on my laptop. I hope this will convince him I don't. ;-)

But you folks were righter, as you'll see after the bcdedit results.

Windows Boot Manager
--------------------
identifier {bootmgr}
device partition=\Device\HarddiskVolume1
description Windows Boot Manager
locale en-US
inherit {globalsettings}
default {current}
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
displayorder {current}
toolsdisplayorder {memdiag}
timeout 30

Windows Boot Loader
-------------------
identifier {current}
device partition=C:
path \Windows\system32\winload.exe
description Windows 7
locale en-US
inherit {bootloadersettings}
recoverysequence {a0a822b1-5076-11e7-a12c-ed5588230eb9}
recoveryenabled Yes
osdevice partition=C:
systemroot \Windows
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
nx OptIn

So I don't have a second operating system.

HOWEVER, I unplugged the flash drive from the USB hub, and since then it
has booted 4 times without complaining that the OS can't be found.

I forget how to get into the BIOS, so I can't check this, but I guess
the problem is that I put the USB port ahead of the HDD in the boot
order. I thought it was supposed to check for an OS and if there wasn't
one, go to the next device. Instead it says "OS not found".

OTOH, having the mouse, the cell phone, and the speakers plugged into
the hub never causes a problem.

So the flash drive was the problem, even though though it had nothing
but data files and one set of program files.

Thanks all for your help.

Your explanation sounds perfectly plausible.

I have one motherboard here, where the BIOS "freezes"
and the computer won't POST, if any drive has an all-zeros MBR.
So they do get carried away with "sniffing stuff"
and "validating before booting".

Paul

In alt.windows7.general, on Thu, 07 Mar 2019 03:57:13 -0500, Paul
wrote:

micky wrote:
In alt.windows7.general, on Sat, 2 Mar 2019 23:59:44 -0600, VanguardLH
wrote:

micky wrote:

Boot configuration data store could not be opened. Access is denied.
Since bcdedit.exe is a console-mode program, did you load the command
shell (cmd.exe) with elevated (admin) privileges? You may have to log
into an adminstrator-level account in Windows to elevate the command
shell. Even then, if UAC is enabled then you have to OK the prompt to
allow access.

Well, it turns out I was right: Now that you explained how to use
bcdedit, and I see the results, I think Paul still thinks I have a
second OS on my laptop. I hope this will convince him I don't. ;-)

But you folks were righter, as you'll see after the bcdedit results.

Windows Boot Manager
--------------------
identifier {bootmgr}
device partition=\Device\HarddiskVolume1
description Windows Boot Manager
locale en-US
inherit {globalsettings}
default {current}
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
displayorder {current}
toolsdisplayorder {memdiag}
timeout 30

Windows Boot Loader
-------------------
identifier {current}
device partition=C:
path \Windows\system32\winload.exe
description Windows 7
locale en-US
inherit {bootloadersettings}
recoverysequence {a0a822b1-5076-11e7-a12c-ed5588230eb9}
recoveryenabled Yes
osdevice partition=C:
systemroot \Windows
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
nx OptIn

So I don't have a second operating system.

HOWEVER, I unplugged the flash drive from the USB hub, and since then it
has booted 4 times without complaining that the OS can't be found.

I forget how to get into the BIOS, so I can't check this, but I guess
the problem is that I put the USB port ahead of the HDD in the boot
order. I thought it was supposed to check for an OS and if there wasn't
one, go to the next device. Instead it says "OS not found".

OTOH, having the mouse, the cell phone, and the speakers plugged into
the hub never causes a problem.

So the flash drive was the problem, even though though it had nothing
but data files and one set of program files.

Thanks all for your help.

Your explanation sounds perfectly plausible.

Was I foolish in thinking it would ignore the flashdrive when it found
no OS on it? And go on to the next listed device?

I have one motherboard here, where the BIOS "freezes"
and the computer won't POST, if any drive has an all-zeros MBR.
So they do get carried away with "sniffing stuff"
and "validating before booting".

It's easy to get carried away.

Paul

In alt.windows7.general, on Tue, 26 Feb 2019 10:00:02 +0000, "J. P.
Gilliver (John)" wrote:

To me, stiction meant the often-hard-to-explain behaviour of
mechanical items where extra effort is required to move them from a
non-moving Poisson (often very noticeable when pushing a car).

I had a non-moving Poisson once. After a couple days, it smelled
terrible.

(I know.. autocorrect.)

In message , micky
writes:
In alt.windows7.general, on Tue, 26 Feb 2019 10:00:02 +0000, "J. P.
Gilliver (John)" wrote:

To me, stiction meant the often-hard-to-explain behaviour of
mechanical items where extra effort is required to move them from a
non-moving Poisson (often very noticeable when pushing a car).

I had a non-moving Poisson once. After a couple days, it smelled
terrible.

LOL!

(I know.. autocorrect.)

You're right. Don't know what I originally typed.
--


What do you think about petitions? See 255soft.uk; #fairpetitions @jpeg_G6 (UK
only)
--
How about a three-way referendum with second choices being taken into account?
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

"The people here are more educated and intelligent. Even stupid people in
Britain are smarter than Americans." Madonna, in RT 30 June-6July 2001 (page
32)

Paul wrote:

micky wrote:
In alt.windows7.general, on Sat, 2 Mar 2019 23:59:44 -0600, VanguardLH
wrote:

micky wrote:

Boot configuration data store could not be opened. Access is denied.
Since bcdedit.exe is a console-mode program, did you load the command
shell (cmd.exe) with elevated (admin) privileges? You may have to log
into an adminstrator-level account in Windows to elevate the command
shell. Even then, if UAC is enabled then you have to OK the prompt to
allow access.

Well, it turns out I was right: Now that you explained how to use
bcdedit, and I see the results, I think Paul still thinks I have a
second OS on my laptop. I hope this will convince him I don't. ;-)

But you folks were righter, as you'll see after the bcdedit results.

Windows Boot Manager
--------------------
identifier {bootmgr}
device partition=\Device\HarddiskVolume1
description Windows Boot Manager
locale en-US
inherit {globalsettings}
default {current}
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
displayorder {current}
toolsdisplayorder {memdiag}
timeout 30

Windows Boot Loader
-------------------
identifier {current}
device partition=C:
path \Windows\system32\winload.exe
description Windows 7
locale en-US
inherit {bootloadersettings}
recoverysequence {a0a822b1-5076-11e7-a12c-ed5588230eb9}
recoveryenabled Yes
osdevice partition=C:
systemroot \Windows
resumeobject {a0a822af-5076-11e7-a12c-ed5588230eb9}
nx OptIn

So I don't have a second operating system.

HOWEVER, I unplugged the flash drive from the USB hub, and since then it
has booted 4 times without complaining that the OS can't be found.

I forget how to get into the BIOS, so I can't check this, but I guess
the problem is that I put the USB port ahead of the HDD in the boot
order. I thought it was supposed to check for an OS and if there wasn't
one, go to the next device. Instead it says "OS not found".

OTOH, having the mouse, the cell phone, and the speakers plugged into
the hub never causes a problem.

So the flash drive was the problem, even though though it had nothing
but data files and one set of program files.

Thanks all for your help.

Your explanation sounds perfectly plausible.

I have one motherboard here, where the BIOS "freezes"
and the computer won't POST, if any drive has an all-zeros MBR.
So they do get carried away with "sniffing stuff"
and "validating before booting".

Paul

BIOSes will load their bootstrap code which then hunts for bootable
media in the order listed in the BIOS setup. If the first device has no
boot loader in the boot sector, the BIOS code may error or it can
present a skip option (sometimes with a timeout to continue for you).
I've run across more of the former type of detection (pukes and halts on
an error) than the latter type (lets you skip the unbootable media to go
to the next). In fact, the latter "feature" is anti-security. Some
users password their BIOS and lock the case (to prevent shorting the
CMOS clear jumper to clear the password) while setting up the boot order
to first pick the hard disk. They don't want users to boot from any
other media. It boots from the hard disk or not at all. So, skipping
to the next media in the boot order list either manually (user presses a
key) or automatically (times out to go to next media) would void the
security of forcing booting only from the hard disk (or whatever media
was first in the boot order).