Life of a Windows operated machine

**mercury** · 07-03-2009 10:11 AM

How long does a machine running Microsoft OS(any) run continuously without shutting down??

Well, below is the answer...

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Here is a bit of information, which may surprise you all. Windows crashes automatically if you don't switch off the machine
for 49.7 Days. Microsoft accepts this. Do you know why? If not read this.
In Windows the Virtual Machine Manager (here after referred as VMM) is responsible for creation, execution, monitoring and termination
of virtual machines. This VMM, which is a 32 bit, protected mode operating system entity, provides a number of system services at
chip level. One of these services is "Get_System_Time". This particular service loads the EAX register with the time in milliseconds since Windows started on that machine. This service is accurate to 1 ms. EAX is a 32 bit register in Intel 386 Processor onwards.
So the maximum number of milliseconds it can hold is
(2 power 32)-1 = 4294967295 milliseconds = 4294967.295 seconds = 71582.79 minutes = 1193 hours = 49.7 days
So after 49.7 days the EAX resets to zero. Most of the Drivers use this Time Service to keep track of the Timeout of various
services they provide. So after 49.7 days the drivers cannot use the get_System_Time function of VMM and they crash taking the OS along with.