Transcript DOS, Win 3X, Win 9X, & Win NT 4.0 Differences

Microsoft
Window 9X
Operating System
Richard Goldman
© February 28, 2001
Operation of Windows 9X
• Windows 95
• Windows 98
• Windows Me
•The computer hardware layer is all the
physical components and devices that
makeup or are attached to the computer.
•The main components of a computer are:
•System Board
•CPU
•Main Memory
•Chip Set
•Disk Drives
•Monitor and Printer
•Keyboard and Mouse
Hardware
Windows 9X
Hardware
Windows 9X
BIOS
•The System BIOS chip contains small programs
called device drivers that allow the software to
communicate with the computer’s hardware.
•Many of the other devices have BIOS chips also.
•These BIOS chips identify the device they are on and
may contain additional drivers.
•When the computer is first turned on, the System
BIOS:
•locates all the devices attached to it,
•loads a driver into memory for each device,
•and performs a brief test of each device (POST).
BIOS
Hardware
Phoenix
•When the BIOS completes the POST it locates
and runs the Boot Record on the default drive.
•The Boot Record locates and runs IO.SYS, also
on the default drive.
Windows 9X
DOS
•IO.SYS loads the DOS core components.
•Then IO.SYS runs CONFIG.SYS and AUTOEXEC.BAT, if present,
to provide support for legacy software or custom configuration.
•IO.SYS runs WIN.COM.
DOS
IO.SYS
BIOS
Hardware
Phoenix
Win 9X
Start
Core
Kernel
User
Drivers Config.
Mgr.
DOS
Hardware
IFS
Virtual
Memory
Manager
Installable
File System
•The VMM then loads the
dynamic device drivers.
•The VMM loads the
remainder to the Kernel, the
User, and the GDI.
IO.SYS
BIOS
VMM
GDI
Windows 9X Core
•WIN.COM loads the Virtual
Memory Manager ( VMM32.VXD)
and the required Windows
VxDs (real mode static device
drivers) plus drivers listed in
the [386 Enh] section of
SYSTEM.INI.
•Window then switches from
16-bit Real Mode to 32-bit
protected mode.
Phoenix
•Finally EXPLORER.EXE is
run to provide a GUI shell.
Windows 9X
Virtual Machines
Win 9X
System VM
DOS VM
WOW
32-bit Win App
32-bit Win App
DOS App
16-bit Win App
DOS VM
16-bit Win App
DOS App
32-bit Win App
Start
Core
Kernel
User
Drivers Config.
Mgr.
DOS
VMM
IFS
Virtual
Memory
Manager
Installable
File System
IO.SYS, MSDOS.SYS, COMMAND.COM
BIOS
Hardware
Phoenix
GDI
•Windows 9X creates a
System Virtual Machine
for all Windows
applications.
•Each 32-bit Windows
application runs in its
own memory space
within the System VM.
•16-bit Windows
applications share a
memory space in the
System VM.
•Each DOS application is
given its own VM.
Windows 9X
Core Functions
Win 9X
System VM
DOS VM
WOW
DOS App
32-bit Win App
32-bit Win App
32-bit Win App
32-bit Win App
16-bit Win App
DOS VM
16-bit Win App
DOS App
16-bit Win App
DOS VM
DOS App
Start
Core
Kernel
User
Drivers Config.
Mgr.
DOS
VMM
IFS
Virtual
Memory
Manager
Installable
File System
IO.SYS, MSDOS.SYS, COMMAND.COM
BIOS
Hardware
Phoenix
GDI
•The Kernel provides
basic operating system
functions:
•File input/output
•Memory management
•Load and execute
programs
•The User component
controls the user interface
– keyboard, mouse, etc.
•The GDI component
manages the graphics
output to the screen and
printer.