The passage of time has been good for computing in most ways.But OS kernel development progresses through evolution, which means as new pieces of technology are attached, other pieces are discarded. And like evolution, at the core kernel level, some parts remain. How does it occur?
So back in 1993, when Microsoft was still in the NT 3.1 environment, BIOS calls in the Virtual-8086 mode monitor code were introduced and have survived up to the time of Windows7. Microsoft, 17 years ago, detailed that there were vulnerabilities associated with this BIOS call
In order to support BIOS service routines in legacy 16bit applications, the Windows NT Kernel supports the concept of BIOS calls in the Virtual-8086 mode monitor code. The flaw exists in the Virtual DOS Machine, which is a system that allows Windows NT to run DOS and 16bit applications on 386 (and up) machines.