Basic OS question [Understanding how OS works!] Help

[rocker123]

Hello,

I have been digging a lot of things about how OS works. Everything looks alright. But I'm unable to understand this scenario.

Suppose:

-> If a Hard Drive has a partitions ( say 4)
-> If an OS has been installed on first partition.

When we try to install the second OS, the question comes as How does the second OS is able to read what the other OS has already written?

I was under an assumption that, Bootloader (MBR) does recognize it but looks like I was wrong. (According to my professor).

I would like someone to clearly explain (If possible provide links) to understand how this thing works.

I would really appreciate if someone can enlighten me.

 

[WR2]

When we try to install the second OS, the question comes as How does the second OS is able to read what the other OS has already written?

The 2nd OS only sees another storage partition and it's files.
As far it's aware it's the 'only' OS on the system. It doesn't care what other OS reside in the other partitions.

 

[WR2]

From: NeoSmart-EasyBCD Bootloader Manager http://neosmart.net/wiki/dashboard.action

 

[13thmonkey]

WR2 has alluded to it, but an OS is 'just a bunch of files' unless it is running.