Why four primary partitions in the nt family

[Stephen M Jones]

How did Microsoft arrive at the quantity of four for
primary partitions (or three and one extended)? The need
for one is obvious. But why the jump to four?

 

[Will Denny]

Hi

The maximum number of Primary partitions is limited to 3 - for the purpose
of dual/triple booting. The one extended partition can then be divided up
into data partitions

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Will Denny
MS-MVP Windows - Shell/User
Please reply to the News Groups


| How did Microsoft arrive at the quantity of four for
| primary partitions (or three and one extended)? The need
| for one is obvious. But why the jump to four?

 

[I'm Dan]

How did Microsoft arrive at the quantity of four for
primary partitions (or three and one extended)? The
need for one is obvious. But why the jump to four?

This has nothing to do with the NT family, and I'm not even sure if it was a
Microsoft decision. I know that the 4-slot partition table was a well
established standard at least as early as DOS 3.0, which is when I began
hacking boot records and partition tables. I recall reading somewhere that
in the early days of hard disks, people would need to multiboot DOS and
CP/M, which at the time had more software apps than Microsoft. Back in
those days there were lots of alternative OS's, and the partition table was
standardized so people could multiboot up to four of them. I believe the
"extended" partition type was an afterthought when it was realized four
might not be enough.

 

[Kent W. England [MVP]]

How did Microsoft arrive at the quantity of four for
primary partitions (or three and one extended)? The need
for one is obvious. But why the jump to four?

The boot sector definition is ancient history, far predating the NT
family of operating systems. The only thing funky about NT/2K/XP is that
you can't boot these OSes from an extended partition, only from a
primary partition. If you want to boot more than four NT-like
partitions, you need a third-party manager like BootItNG that supports
partition hiding. And no matter what the MBR says, NT-like OSes look at
the disk directly and get upset if you slide the partition around (but
they don't stay upset for long).

The new 64 bit Windows OSes have a new boot setup.