Will Windows work continuously for more than 49.7 days?

[aarklon]

Hi all,

I recently got an email from my friend in the following lines:-

Will Windows work continuously for more than 49.7 days?

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?

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
(232)-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.



To what extent the above statements are true ?

 

[JS]

It's an old Window 95/98 issue.
See: Computer Hangs After 49.7 Days
http://support.microsoft.com/kb/216641

Did this happen very often.
For me it did since I had to service PC(s) in a Hospital environment,
and the ER was open 24Hrs a day and seven days a week.
So the PCs were never turned off, but this is past history.

JS

 

[Detlev Dreyer]

I recently got an email from my friend in the following lines:-

Will Windows work continuously for more than 49.7 days?

[Nonsense snipped]

To what extent the above statements are true ?

Not really true anymore. The bottleneck was the outdated Win3/Win9x
"GetTickCount" function which shouldn't be used anymore. See also
http://msdn2.microsoft.com/en-us/library/ms724408.aspx

 

[JohnB]

The question should be: "Will windows work continuously for 49.7 days
without doing something stupid, inexplicable or cause the user to, out of
frustration, throw the computer out in the parking lot and drive over it
with your car!!"

 

[PA Bear [MS MVP]]

I recently got an email from my friend...

Did your friend send you the email on April Fools Day?

 

[JS]

Maybe it was sent 49.7 days before April Fools Day

JS

 

[M.I.5¾]

The question should be: "Will windows work continuously for 49.7 days
without doing something stupid, inexplicable or cause the user to, out of
frustration, throw the computer out in the parking lot and drive over it
with your car!!"

I remember thinking when I first saw that problem, "How did anyone find
out?". ;-)

 

[Bob I]

I remember thinking when I first saw that problem, "How did anyone find
out?". ;-)

Seems that Win95 had been out 4 or 5 years before the issue was
itentified and the cause was determined.

 

[John John]

Seems that Win95 had been out 4 or 5 years before the issue was
itentified and the cause was determined.

Probably because it took that long to even figure out how to run Windows
95 continuously for more than 2 days! As with all W9x systems an
application crash usually required the "three finger salute" to fix and
if applications didn't crash the out of control Windows 95 Vcache would
bring the computer to a halt long before the 49.7 days uptime limit!

John

 

[Ken Blake, MVP]

I recently got an email from my friend in the following lines:-

Will Windows work continuously for more than 49.7 days?
(snip)

To what extent the above statements are true ?

Not at all. It *was* true many years ago, on Windows 95 and 98. See
http://support.microsoft.com/kb/216641

 

[M.I.5¾]

Hi all,

I recently got an email from my friend in the following lines:-

Will Windows work continuously for more than 49.7 days?

In the case of Windows XP, it mosr cerainly does run for more than 49.7
days. This box I am typing on (and the one next to it come to that) is only
ever shut down and rebooted if it becomes necessary. This happens only
occasionally, and the last time was only because they weren't going to be
used for over a week (something to do with Christmas).