Windows 9X Core Components

Introduction to Windows 9x Core Components

• Windows 9x has a number components built within it which are revolutionary in for an operating system  at its time of development.

• In order to understand windows, we need to become aware of its core components  and understand how each component operates in windows 9x . We also need to be aware of how windows runs applications  designed for its processors such as DOS  and Windows 3x.

• At its base it has a hybrid kernel  enabling it to run both 16 bit  and 32 bit programs , it has built-in plug and play, preemptive multitasking  and much much more.

Key Topics

Windows 9x Hybrid Core Core Files Memory Organization Virtual Machine Cooperative and Preemptive multitasking

Device Drivers Virtual Drivers Introduction to Plug and play Plug and Play  activation.

 

 

Windows 9x Hybrid Core and Thunking

• Windows 9x is sometimes defined as a hybrid operating system  that means that it has built in 16 bit  and 32bit core components .

• Windows 9x uses 32bit coding whenever possible, which gives it such high performance , and 16bit coding when application, demand it or performs thunking  if there is no alternative.

• Thunking performs a conversion of 16bit code to 32bit when communicating with the OS core components . This conversion is time consuming and processor intensive

Core files  of Windows 9x

• There are three main core components  in windows 9x  that include the kernel component , the user component, and the GDI  components.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Windows 98 Backwards Compatibility

• Since Windows 9x is a superior hybrid operating system  which is backwards compatible  and supports 16bit real mode  DOS  programs , 16bit Protected mode Windows 3.1 programs and also supports its own 32bit programs, it must ultimately have a method of dealing with all these programming designs in one environment.

Running DOS  and Windows 3.1 programs

• Windows 9x runs all these programs  in separate regions of the system memory  in effect simulating the programs native environment

Running DOS  Programs

• DOS  programs  are designed to take full control  of your system and not to share any of the system resources  with any other application.

• Windows 9x uses virtual machines  that emulate a DOS  environment allocating a pre-designated portion of the system recourses to the application fooling the DOS application as to having full control  over the system.

• These DOS  virtual machines  are allocated different portions of the memory  and are kept separate from each other.

Windows 3.1 Programs

• Windows 3.1 programs  are designed for cooperative multitasking  and can share resources .

• All 16-bit  windows programs  are ran in the same region in the memory  called the heap.

• Cooperative multitasking means that all the 16 bit  programs  must cooperate in time sharing  the system resources  among each other

• If one of the 16bit programs  in cooperative multitasking  fails it does not release its handles on the system resources  that results in all the Windows 3.1 programs failing and a general protection fault.

• In a windows 3.1 environment such applications  errors  would ultimately result in restarting the system.

Loading Windows 9x Programs

• Windows 9x loads and runs all 32bit windows application in its own compartmentalized  protected region in the system RAM .

• This would mean that applications  do not interfere with each other and if one program runs into errors , all other 32-bit programs  remain unaffected.

Preemptive Multitasking

• Windows 9x uses preemptive multitasking  which means that the operating system  controls which application use the system resources , and if an application fails the operating system will disconnect the application handles from the processor and other resources.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Windows 9x Drivers

• A driver  can be thought of as a program designed for the operating system  to communicate with that particular hardware. A driver informs the OS of the limitations of that device and allows the OS to communicate to the device with device specific commands rather than generic  commands.

• All OS have generic  drivers  that may be able to communicate with the device of interest but may not be able to use the hardware’s specialized features,

• (e.g. for printers , not print at high resolutions,

•  For VGA  cards, limited colors and resolution ,

• For modems , low baud rate communication  etc).

• Since all Devices require a driver  to function in Windows 9x, Windows automatically installs all the drivers  for the standard hardware such as your keyboard , mouse  etc,

• For new devices  or legacy  devices you may need to contact the manufacturer of the hardware through the Internet  to obtain the latest drivers  for that device.

Virtual Device Drivers

• Windows 9x is designed to prefer to use virtual 32bit device drivers  for several reasons and converts all possible 16bit drivers to 32bit protected mode  drivers.

• The reasons for converting drivers  are:

• Virtual 32bit drivers  are used by plug and play

• Better performance , reliability  and speed over 16 bit  drivers .

• Real mode legacy  device drivers  force the system to work in real mode  that slows down the operating system .

• 16bit real mode  will reduce multitasking capabilities because they were not designed for preemptive multitasking .

Introduction Plug and Play

• Plug and Play  is a collaboration between hardware manufactures to standardize all hardware and to have the hardware identify and configure itself with the plug and play operating system  making the installation  of the hardware automatic

Collaboration in plug and play

• Three components of your system must collaborate fully for plug and play to become fully operative,

a)      The system BIOS  must be plug and play compatible.

b)      All expansion cards and other devices  must be plug and play compatible.

• The operating system  must support plug and play which windows 9x  does.

• The specifications of plug and play including

• All PCI  devices  must be plug and play

• All ISA  devices  manufactured after 1993 must be plug and play.

• A 32 bit VxD virtual device driver  must be installed for all Windows 9x compatible hardware.

Services of plug and play

• Plug and play has two main services  built in to it that are Resource Management and Runtime Configuration.

• Resource Management

• Activated when windows is starting and check all hardware installed and its resource requirements

• Runtime Configuration

• Monitors  the system continually for added devices  whiles the system is functioning and if device is added it will automatically load its drivers  if available and activates the device either immediately or after a reboot of the system.

Components of plug and play

• There are four major components to plug and play that ensure that the system monitors and configures all the devices , allocates the required resources  to the devices, inventories the current hardware and associated drivers  in its database.

• The four components are called the Configuration Manager, the Hardware  Tree, the Bus Enumerator  and the Resource Arbitrator .

Plug and Play  Activation

• Plug and play is activated in four different situations

• Windows Installation

• As windows are being installed, it will install all required 16 bit  and 32 bit drivers  and configure the devices .

• System Boot Startup

• Whenever Windows is started it communicates with the plug and play BIOS  and if new devices  are added, it will configure and install all required drivers .

• Continuously

• While windows is up the runtime configuration component is active and monitoring any hot swappable  devices  added like USB  and installing them automatically if drivers  are available.

• Manually Activated

• By running Add Remove Hardware  in Control Panel

 

 

 

 

 

 

 

 

 

 

 

 

 

Questions

1. What are the core components  of the Windows operating system? (Choose all that apply)

1. Kernel  files

2. User files

3. GDI  files

4. Screen files

5. Driver files

2. What sort of multitasking is employed by windows98

1. Cooperative multitasking

2. Defensive Multitasking

3. Preemptive Multitasking

4. Effective Multitasking

3. How does windows run DOS  programs

1. Uses separated windows

2. Uses slit windows

3. Uses virtual machines

4. Uses Window machines

4. What are the cooperating components of plug and play? (Choose all that apply)

1. PCI  devices

2. Plug and play BIOS

3. Connectors

4. Plug and play operating system

5. When is plug and play activated? (Choose all that apply)

1. During installation

2. During startup

3. Continuously for hot swappable  devices

4. Manually using Add/remove hardware

5. Continuously for all devices

Answers

1.      A,B,C

2.      C

3.      C

4.      A,B,D

5.      A,B,C,D