Windows NT 4.0 and System Partition Limits

Hardware prices have dropped significantly in the past few years. 
Although CPUs and memory are now very inexpensive, nothing has dropped 
in price more than storage. At the same time it's getting larger, 
storage is becoming more reasonably priced. Hard drives larger than 80 
GB aren't uncommon. 

Windows NT 4.0 was released in 1996 when hard drives weren't nearly as 
large as they are today. The NTFS file system theoretically supports 
partitions of up to 16 exabytes (EB). Although this theoretical limit 
won't be reached in the near future, another limitation that can cause 
trouble has already been reached--the limitation of system partition 
size in Windows NT 4.0. The system partition contains the files 
necessary for the initial system startup (NTLDR, Ntdetect.com, 
Boot.ini). 

When the computer boots, the only way for Windows NT to access the hard 
drive is to use a set of BIOS functions known as Interrupt (INT 13). 
When INT 13 was developed, multigigabyte hard drives weren't available 
and INT 13's limitation of 7.8 GB wasn't seen as critical. 

As a consequence, Windows NT 4.0 can't access more than 7.8 GB during 
the first stages of the boot process; thus, the system partition is 
limited to 7.8 GB. Newer operating systems such as Windows 98 and 
Windows 2000 don't suffer from this limitation because they use a newer 
extended INT 13 that can address more than 7.8 GB.