CSE 5343/7343 Fall 2006 Case Studies

1
CSE 5343/7343Fall 2006Case Studies

• Windows History/Processes
• MS DOS to Windows NT

2
Windows Case Study Outline

• History
• MS-DOS
• Windows 3.xx
• Windows NT
• Windows 2000
• Windows XP
• Design Philosophy
• Process Management

3
CAUTIONThere are so many variations of
Windows. Each version is different. Some are
drastically different (even if the GUI is
similar.)
4
MS-DOS History (1 pp 633-639)

• 1975
• First real PC, Altair, developed by Micro
  Instrumentation Telemetry Systems based on Intel
  8080 8-bit microprocessor with 256 bytes of
  memory.
• Bill Gates and Paul Allen of Microsoft develop a
  version of Basic for Altair.
• CP/M was dominant OS.
• IBM asked Microsoft to develop a ROM BASIC. IBM
  chose Intel 8088. Gates suggested IBM use
  CP/M-86. IBM met with Digital Research and
  CP/M-86 was running late. Microsoft decided to
  write its own OS. Microsoft purchased 86-DOS
  from Seattle Computer Products.

5
MS-DOS History (contd)

• 1981 MS-DOS prototype running in February and
  appeared in IBM PC announcement (MS-DOS 1.0) in
  August.
• 4000 lines of assembly code
• 12K memory
• CP/M compatible
• Device independent I/O treated as files in Unix
• Command processor had a resident and transient
  part

6
MS-DOS History (contd)

• MS-DOS 2.0 March 1983
• 20,000 lines of code
• IBM PC/XT with 10M hard disk
• Hierarchical file system (as in Unix)
• Device drivers
• Users wanted multi-tasking, but instead Microsoft
  added the ability for a print spooler to run
  concurrently with other tasks in background mode
  as time permits. When MS-DOS has nothing to do
  an interrupt is generated to run the print
  spooler.

7
MS-DOS History (contd)

• MS-DOS 3.0 August 1984
• 40,000 lines of code
• PBM PC/AT with 20M hard and 1.2 floppy
• Intel 80286 16M address space
• 24 bit addresses
• Ring protection mechanism
• Cooperative multitasking
• Virtual memory
• Real address mode 1 MB address space acts as
  fast 8086
• Protected mode All 16 MB

8
Windows History (3,4)

• Early Windows
• Not true OS just a new GUI layer with fixes to
  address memory constraints.

9
Windows History (contd)

• Problems with DOS/Windows 3.1
• 16 bits Cant access all of memory.
• 1M barrier for memory
• Cooperative multitasking
• Nonreentrant
• Lost system resources
• Win16 applications overwriting memory of another

10
Windows Question

• Who invented windows?
• Who invented the mouse?

ANSWER XEROX PARC
11
Windows 95 Design (3)

• Design Goals
• Less than 4MB
• Backward compatible (Support Win16 and DOS)
• Increased stability Fault handler is not part
  of application.
• Three major portions
• User I/O manager Windows manager
• GDI GD manager
• Kernel Memory, Files, Task managers

12
Windows 95 Design (contd)

• Registry
• Central information including startup and init.
• Supports plug and play
• Virtual Machine used to run Win16 applications.
• User mode kernel mode
• Long file names

13
OS/2 Design (5)

• Microsoft/IBM designed to replace DOS on Intel
  machines
• Early 1990s Microsoft released Windows 3.0 which
  took over the market
• IBM viewed Windows as stepping stone to OS/2
• Microsoft wanted to have Windows compete with
  OS/2
• IBM/Microsoft split

14
Windows NT Design(3,5,6)

• New Technology
• DEC (RSX VMS ELN) NT
• VMS 1 WNT (HAL 1 IBM)
• All major designs of David Cutler
• 1993, versions 3.1, 3.5, 3.51, 4.0
• Mostly C/C
• 3.1 had same GUI as Windows
• 32-bit OS

15
Windows NT Design (contd)

• Preemptive multi-tasking
• Supports multiple processors
• Used on many architectures
• Backward compatibility
• Fully reentrant code
• Object oriented

16
Windows NT Design (contd)

• NTFS NT File System
• Permissions for file/directory and all objects
• Security
• Domain Set of machines with similar uses and
  authorizations
• Registry contains information about OS and
  application configurations
• Hardware
• Installed software
• Applications and file types
• Current user
• Actively loaded user profiles

17
Windows 2000 Design(5,7)

• (AKA) Windows NT 5.0
• Distributed File System
• Multiple monitors
• Objects
• Event , Mutant, Mutex, Semaphore, Thread, Timer
• Interrupt, Asynchronous Procedure Call (APC),
  Process
• Subsystems provide backward compatibility
• Like virtual machines

18
Windows XP Design (7)

• 32/64 bit
• Preemptive multitasking
• October 2001 released
• Client-server architecture for multiple processors

19
Win32 Subsystem (6)

• Used in most Windows OSs
• Window manager
• Process/Thread
• CreateFile
• GetMessage

20
Windows Process Management
21
MS-DOS Processes (2)

• Single tasking since functions are nonreentrant.
• Only real multitasking is background for
  printing. Can change time slice for this.
• EXEC function used by COMMAND.COM
• Allocate memory
• Write program segment prefix
• Load program into memory
• Transfer control to program
• Child may in turn use EXEC

22
Early Windows Processes(2)

• Cooperative multitasking
• Windows program voluntarily yields control at
  certain times (Windows 4 and 6.2)

23
Windows NT Processes (6)

• Executable program (code and data)
• Private virtual address space
• System resources (semaphores, ports, etc)
• Process ID
• Threads

24
Windows NT Threads (6)

• Registers
• Stacks (kernel, user)
• Private storage (used by subsystems)
• Thread ID (client ID)
• Mode transition (switch from user mode to kernel
  mode) does not require a context switch.
• Test
• Windows Task Manager/Performance
• Control Panel/Administrative Tools/Performance

25
Windows NT Handles (6)

• Provides ability to access an object at a certain
  level of priviledge.
• Handle Table entry in EPROCESS block
• Standardized interface to objects

26
Windows NT PCB (6)

• Executive (EPROCESS) blocks
• ETHREAD blocks
• Process Environment Block (PEB)
• Thread Environment Block (TEB)

27
Windows NT Fibers (6)

• NT 3.51
• Subsets of threads
• Lightweight threads
• User level threads
• Scheduled to run by programmers not OS

28
Windows NT Process States (6)

• Ready
• Standby Next to run
• Running
• Waiting
• Transition Ready to run but kernel stack paged
  out
• Terminated

29
Windows NT Quantums (6)

• Default
• 6 on Windows NT Workstation
• 36 on Windows NT Server
• Units are not time values, but relative
• At clock interrupt, 3 is deducted from quantum if
  it is 0 then another thread may run.

30
Windows NT Thread Scheduling (6)

• Preemptive priority
• Multilevel queues RR within queue
• Scheduling independent of process
• Threads have processor affinity
• If thread is preempted, it is put at the front of
  the ready queue for that priority. When
  scheduled it receives the rest of its quantum.

31
Windows NT Priorities (6)

• 32 priority levels
• 16-31 real time
• 1-15 variable levels
• 0 system level
• Priority classes
• Real time, High, Normal, Idle
• Threads (Type with Class)
• Time critical, Highest, Above normal, Normal,
  Below normal, Lowest, Idle

32
Windows NT Priorities (6)

• Default base priority level within class
• Thread has base and current priority
• Priorities raised (1-15 range never above)
• After wait state
• Entering wait state
• Threads not getting CPU time
• Priority goes down after each quantum until base
  is reached

33
IPC(3,4,7)

• Windows 95
• Thunking
• Allows 16bit modules to communicate with 32bit
• Routine that maps addresses

34
IPC (contd)

• Messages
• Queue per thread
• Semaphores
• Win16 mutex
• Used to prevent to Win16 applications from
  executing the same code
• Ignored by Win32 applications
• Limits multitasking

35
IPC (contd)

• Clipboard
• Actually shared memory
• OLE (Object Linking and Embedding)
• Windows 95
• Drag Drop
• Enhancement to DDE
• Embed or link data from one application to
  another.
• Link pointer to data
• Embed actually move

36
IPC (contd)

• DDE (Dynamic Data Exchange)
• Windows 3.1
• Protocol that allows Windows applications to
  share data.

37
IPC (contd)

• Deferred Procedure Call (DPC)
• Windows NT/2000
• System function will be (ultimately) executed
• IRQL (Interrupt Queue Level)
• Asynchronous Procedure Call (APC)
• Like DPC but for users
• Nonblocking
• Both are viewed as software interrupts

38
References

• Harvey M. Deitel, Operating Systems Second
  Edition, Addison-Wesley, 1990.
• Mark Minasi, etal., Inside MS-DOS 6.2 Second
  Edition, New Riders Publishing, 1993.
• Jime Boyce, etal., Inside Windows 95, New Riders
  Publishing, 1995.
• Richard Wagner, Jim Boyce, Forrest Houlette,
  Randall Kennedy, and Keven Stoltz, Ultimate
  Windows 3.1, New Riders publishing, 1993.
• John Savill, The Windows NT and Windows 2000
  Answer Book A Colmplete Resource from the Desktop
  to the Enterprise, Addison-Wesley, 1999.
• David A. Solomon, Inside Windows NT Second
  Edition, Microsoft Press, 1998.
• Abraham Silberschatz, Peter Baer Galvin, and Greg
  Gagne, Windows XP Update Operating System
  Concepts Sixth Edition, 2003, John Wiley Sons.