Brief History of Widows NT is a family of operating systems produced by Microsoft. The first version of which was released in July 1993 is the Windows NT 3.1 a 32-bit OS. It is a processor-independent, multiprocessing, multi-user operating system. Architecture of Windows NT is a layered design that consists of two main components, user mode and kernel mode. It is a preemptive, reentrant operating system, which has been designed to work with uniprocessor and symmetrical multi processor (SMP)-based computers. To process input/output (I/O) requests, they use packet-driven I/O, which utilizes I/O request packets (IRPs) and asynchronous I/O. User Mode made up of subsystems which can pass I/O requests to the appropriate kernel mode drivers via the I/O manager. Two types of User Mode Subsystem Environment Subsystem designed to run applications written for many different types of operating systems. None of the environment subsystems can directly access hardware, and must request access to memory resources through the Virtual Memory Manager that runs in kernel mode. Environment Subsystem is divided into three: Win32 subsystem  It can run 32-bit Windows applications.  It also supports Virtual DOS Machines (VDMs), which allow MS-DOS and 16-bit Windows (Win16) applications to run on Windows NT. OS/2 subsystem   supports 16-bit character-based OS/2 applications and emulates OS/2 1.x, but not 32-bit or graphical OS/2 applications as used with OS/2 2.x or later, on x86 machines only. Windows 2000 (last version that uses the OS/2 as the subsystem.  POSIX subsystem it supports applications that are strictly written to either the POSIX. Standard or the related ISO/IEC standards.  Interix replaced POSIX subsystem. Kernel mode has full access to the hardware and system resources of the computer and runs code in a protected memory area. It controls access to scheduling, thread prioritization, memory management and the interaction with hardware. It is consist executive services, which is itself made up of many modules that do specific tasks, kernel drivers, a kernel and a Hardware Abstraction Layer, or HAL. Thank You!

2.  is a family of operating systems produced
by Microsoft.
 The first version of which was released in July
1993 is the Windows NT 3.1 a 32-bit OS.
 It is a processor-
independent, multiprocessing, multi-user
operating system.

3. Windows NT releases
Version
Marketing
name
Editions Release date
Build
number
3.1
Windows NT
3.1
Workstation
(named
just Windows
NT),
Advanced
Server
July 27,
1993
528
3.5
Windows NT
3.5
Workstation,
Server
September
21, 1994
807
3.51
Windows NT
3.51
Workstation,
Server
May 30,
1995
1057
4.0
Windows NT
4.0
Workstation,
Server,
Server
Enterprise
Edition,
Terminal
Server,
Embedded
July 29,
1996
1381

5.  is a layered design that consists of two main
components, user mode and kernel mode.
 It is a preemptive, reentrant operating
system, which has been designed to work
with uniprocessor and symmetrical multi
processor (SMP)-based computers.
 To process input/output (I/O) requests, they
use packet-driven I/O, which utilizes I/O
request packets (IRPs) and asynchronous I/O.

6.  User Mode
◦ made up of subsystems which can pass I/O
requests to the appropriate kernel mode drivers
via the I/O manager.
 Two types of User Mode Subsystem
◦ Environment Subsystem
 designed to run applications written for many
different types of operating systems. None of the
environment subsystems can directly access hardware,
and must request access to memory resources through
the Virtual Memory Manager that runs in kernel mode.

7.  Environment Subsystem is divided into three:
◦ Win32 subsystem
 It can run 32-bit Windows applications. It also
supports Virtual DOS Machines (VDMs), which
allow MS-DOS and 16-bit Windows (Win16)
applications to run on Windows NT.
◦ OS/2 subsystem
 supports 16-bit character-based OS/2 applications
and emulates OS/2 1.x, but not 32-bit or graphical
OS/2 applications as used with OS/2 2.x or later, on
x86 machines only.
 Windows 2000 (last version that uses the OS/2
as the subsystem.

8. ◦ POSIX subsystem
 it supports applications that are strictly written to
either the POSIX. Standard or the
related ISO/IEC standards.
 Interix replaced POSIX subsystem.

9.  Kernel mode
◦ has full access to the hardware and system
resources of the computer and runs code in a
protected memory area.
◦ It controls access to scheduling, thread
prioritization, memory management and the
interaction with hardware.
◦ It is consist executive services, which is itself made
up of many modules that do specific tasks, kernel
drivers, a kernel and a Hardware Abstraction Layer,
or HAL.

11.  Software Application

12.  Accessories

13.  Control Panel

14.  Games

15. Windows version CPU RAM Free disk space
NT 3.1
NT 3.1
Advanced Server
i386, 25 MHz
12 MB
16 MB
90 MB
NT 3.5
Workstation
NT 3.5 Server
i386, 25 MHz
12 MB
16 MB
90 MB[53]
NT 3.51
Workstation
NT 3.51 Server
i386, 25 MHz
12 MB
16 MB
90 MB[53]
NT 4.0
Workstation
NT 4.0 Server
i486, 25 MHz
12 MB
16 MB
124 MB