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for XP:
A user mode program can't directly get into kernel mode - the OS prevents all attempts to execute code or access memory outside the program's assigned process space or touch hardware. A driver runs in kernel mode by the simple fact of being a driver, recognized as such and loaded by the OS. Note that there are software-only drivers - a driver that does not control hardware.
Judy
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Thnankx
I understand ...
On the MainFrame a PC or SVC rtn can automatically be invoked in Supervisor state
Just trying to relate the concepts
Thankx
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ForNow wrote: why would I want to be in Kernal Mode
If you were writing device drivers, or any code that needs to access hardware directly.
Morality is indistinguishable from social proscription
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...and going forward not even all of that. I read that Vista had sound drivers yanked out of kernal mode so that Creative could no longer BSOD the OS with their badly written soundbastard drivers. I'm not sure if they pulled anything else out or not at the same time.
Otherwise [Microsoft is] toast in the long term no matter how much money they've got. They would be already if the Linux community didn't have it's head so firmly up it's own command line buffer that it looks like taking 15 years to find the desktop.
-- Matthew Faithfull
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Yep, Vista brings WDF, user mode drivers, but the transitions from uer to kernel are expensive. But it will be more stable.
However, for real drivers (like MINE : ), its the kernel!
dan neely wrote: They would be already if the Linux community didn't have it's head so firmly up it's own command line buffer that it looks like taking 15 years to find the desktop.
Have to say, Ubuntu is really quite nice. Good UI, good updating, stable, it realy does just work. And it ships with a WoPro and spread sheet.
Morality is indistinguishable from social proscription
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It's instructive to compare modern Windows to DOS. In classic DOS, a program could write to any address in the system, potentially overwriting operating system data structures. It could also control any I/O device in the system. Very powerful, but also very dangerous as any program could crash the system or corrupt data. It also made sharing of I/O devices between programs pretty difficult.
This problem had been recognized previously in the mainframe and minicomputer worlds, and hardware had been added to add modes, typically called 'user mode' and 'supervisor mode', with certain instructions reserved for supervisor mode and the ability to protect regions of memory and I/O devices so that only code running in supervisor mode can read from or write to them. User mode - application code - can only then perform these tasks indirectly by requesting that the supervisor (or kernel) carry out the task for it. If it tries to perform such an operation, the CPU instead raises a fault (or exception) to the supervisor; the supervisor can then do whatever is required to fix the fault, or terminate the program.
The processor boots up in kernel mode, then when running a program it runs it in user mode. On x86 this is done by changing a couple of bits in one of the registers, but only supervisor mode code can change that. To get back into supervisor mode, you used to have to issue a software interrupt but in recent processors, the SYSENTER instruction was added. Hardware interrupts also put the processor into supervisor mode, with a return-from-interrupt instruction putting it back into user mode if the processor was running user-mode code when the interrupt occurred.
Generally operating systems try to keep as little code as possible in kernel mode, as the opportunity for this code to do damage is great. User-mode code should only be able to crash the process, not crash the whole system. Where the kernel only has responsibility for memory allocation and thread scheduling, with I/O performed by user-mode processes, this is typically called a microkernel. Windows Explorer and Internet Explorer are both user-mode processes.
DoEvents: Generating unexpected recursion since 1991
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Thankx My only then is can a User Mode program issue the SetKmode api....
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Aha! You didn't say you were working on Windows CE!
SetKMode isn't a good idea, was never officially documented for use by application developers, and was removed in CE 6.0. However, on platforms where it is implemented, it does indeed flip into kernel mode (through a software interrupt, I imagine) and continue running that thread.
I've been a CE developer for six years and never needed SetKMode.
DoEvents: Generating unexpected recursion since 1991
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Its Windows XP If so how do get into Kernal Mode is it my writting a device driver a app with a .sys extension
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Hi
I have a belkin wireless modem / router. It has four wired ports which are all in use. Is it possible to add a 8 port hub to this? I know less than nothing about network hardware and googling is just throwing up new wireless modems.
I am running one of the wires from the hub into the loft and back down into the lads bedroom. I want to, ideally, plug that into another hub in the loft, so I can then run 8 more devices from it. (actually 7 more, as I still need to connect the lads machine up).
Is this as easy as just buying a hub?
The wireless access in the house is rubbish, as the study is at one end of the house, the house is old and all walls are either 9" or 4" solid.
Cheers
Malcolm
We violated nature and our children have to pay the penalty
Don't go near the water children... Johnny Cash - 1974
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Using a hub in such a sense should work fine.
However using a switch would be better.
A hub sends alla data going through it to all other computers/devices while a switch sends the data to the corresponding computer/device.
Switches are therefore faster (under larger amounts of load) and more secure. I would never use a hub today.
You can connect multiple switches/hubs after each other (series) or besides each other (parallel) depending on where you want the new ports.
//Johannes
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So, the router is in the study and three devices are attached to it? Plus one cable that now goes to another part of the house? And you want to add a hub in the middle? Should work ok, but might only offer limited network access. As someone already explained, a hub basically is a multi-port repeater. What goes in on one port comes out on all other ports. This also means that a hub will only run with the lowest common denominator of all devices in the network. If there is an IP-TV box, that MIGHT mean 10 Mbit / Half Duplex.
A switch, however, is a multiport bridge, meaning that it at least does basic OSI/ISO layer 2 routing and mixing. It will remember the port a device is attached to and send all packets addressed to a device to its specific port. A switch also has a backplane that offers seperate throughput for all ports, meaning that port 1 can talk to port 3 with gigabit connectivity, while ports 2 and 4 get data at 100 MBit/s delivered from a gigabit link on port 5... etc.
If you think that several of the devices attached on the breakout switch might be used at once, it might be no bad idea to set them to a bitrate one level slower that the uplink to your router (e.g. router<->switch: Gbit, switch<->devices: 100Mbit).
Oh, and you usually will only have six additional ports available. You will probably need one port to act as an uplink to your router.
Cheers,
Sebastian
--
"If it was two men, the non-driver would have challenged the driver to simply crash through the gates. The macho image thing, you know." - Marc Clifton
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I am developing a software where I store the Instance ID of every disk in the system. How can I get the Instance ID from a disk number? e.g I want Instance ID of DIsk0 DIsk1 etc.?
here is what I am doing
1] SetupDiClassGuidsFromNameA("DiskDrive",***);
to get the GUID for disk drives
2]SetupDiEnumDeviceInf(***) to enumrate all the disks.This gives me Instance ID's of all the disks
but how can I get the device instance ID of spesific disk(like Disk0)?
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Your best bet is to use WMI. The following code was pulled from Microsoft's WMI Code Creator (you can download it from their website):
strComputer = "." <br />
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\CIMV2") <br />
Set colItems = objWMIService.ExecQuery( _<br />
"SELECT * FROM Win32_DiskDrive",,48) <br />
For Each objItem in colItems <br />
Wscript.Echo "-----------------------------------"<br />
Wscript.Echo "Win32_DiskDrive instance"<br />
Wscript.Echo "-----------------------------------"<br />
Wscript.Echo "DeviceID: " & objItem.DeviceID<br />
Next
This is a .vbs script, but the WMI Code Creator will output to VB.NET and C# as well.
Hope this helps...
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i need some help about my stepper motor. it is a philips MB11-4786
and i dont know which circuit i should use.
modified on Wednesday, January 23, 2008 6:42:01 PM
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Does google have anything on it?
"I guess it's what separates the professionals from the drag and drop, girly wirly, namby pamby, wishy washy, can't code for crap types." - Pete O'Hanlon
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i've just got some information about my step motor.
i think it can be drived uln2803 but i am not sure.
actually i didnt understan what they mean.
i am giving you an adress belove. after that please tell me waht i will do.
by the way thanks for your answer.
http://www.reuk.co.uk/Examining-a-Stepper-Motor.htm[^]
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Don't know what you intend making, but the web page you quoted is straight forward. However, here is a blog that uses the parallel output to drive two stepper motors attached to an etch-a-sketch. http://zedomax.com/blog/tag/uln2803/[^].
modified 1-Aug-19 21:02pm.
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My question is on Intel's New Quad Core Processor Technology
This Quad Core Means - 4 CPU?
And if there is not 4 CPU(Processor) Then How it is Quad Core
It is same applicable for Core 2 Duo?
Actually what are this Terminology Means? 
Believe Yourself™ :->™
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Hi
Pentium is a technology as Core is both being produced by Intel.
P1,P2...P4 are the series of advancemnts as Core and Core2 are.
So far as Solo, Duo and Quad is concerned they are the number of procesing elemnts(CPU)
present based on Core technology.
Spread wat u Know!
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Quad Core means four CPU cores on a single die.
I believe that AMD's quad-core CPUs are truly four independent cores, where Intel's are actually two dual-cores. AMD claims their's is better. This all happened last year, and I haven't really been paying attention to this stuff since just before the hardware actually hit the street.
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
-----
"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001
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John Simmons / outlaw programmer wrote:
I believe that AMD's quad-core CPUs are truly four independent cores, where Intel's are actually two dual-cores. AMD claims their's is better.
In theory it is, in practice you need a 4 threaded app with heavy cross thread communications to realize the benefit. At the same time, Conroe is performing enough better than Phenom that it doesn't matter. They were roughly equal on a per clock basis but Phenom took a 10% hit due to a hardware bug (revision with the fix eta a few months) and Conroe will run at significantly higher clockspeeds.
Otherwise [Microsoft is] toast in the long term no matter how much money they've got. They would be already if the Linux community didn't have it's head so firmly up it's own command line buffer that it looks like taking 15 years to find the desktop.
-- Matthew Faithfull
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