CSE 5343/7343
Fall 2006
Case Studies
Windows History/Processes
MS DOS to Windows NT
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Windows Case Study Outline
• History
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MS-DOS
Windows 3.xx
Windows NT
Windows 2000
Windows XP
• Design Philosophy
• Process Management
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CAUTION:
There are so many variations of
Windows. Each version is
different. Some are drastically
different (even if the GUI is
similar.)
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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.
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MS-DOS History (cont’d)
• 1981 – MS-DOS prototype running in
February and appeared in IBM PC
announcement (MS-DOS 1.0) in August.
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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
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MS-DOS History (cont’d)
• MS-DOS 2.0 – March 1983
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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.
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MS-DOS History (cont’d)
• MS-DOS 3.0 – August 1984
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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
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Windows History ([3],[4])
• Early Windows
– Not true OS just a new GUI layer with “fixes”
to address memory constraints.
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Windows History (cont’d)
• Problems with DOS/Windows 3.1
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16 bits; Can’t access all of memory.
1M barrier for memory
Cooperative multitasking
Nonreentrant
Lost system resources
Win16 applications overwriting memory of
another
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Windows Question
Who invented windows?
Who invented the mouse?
ANSWER: XEROX PARC
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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
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Windows 95 Design (cont’d)
• 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
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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
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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
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Windows NT Design (cont’d)
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Preemptive multi-tasking
Supports multiple processors
Used on many architectures
Backward compatibility
Fully reentrant code
Object oriented
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Windows NT Design (cont’d)
• 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:
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Hardware
Installed software
Applications and file types
Current user
Actively loaded user profiles
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Windows 2000 Design([5],[7])
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(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
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Windows XP Design ([7])
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32/64 bit
Preemptive multitasking
October 2001 released
Client-server architecture for multiple
processors
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Win32 Subsystem ([6])
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Used in most Windows OSs
Window manager
Process/Thread
CreateFile
GetMessage
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Windows
Process
Management
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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
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Allocate memory
Write program segment prefix
Load program into memory
Transfer control to program
Child may in turn use EXEC
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Early Windows Processes([2])
• Cooperative multitasking:
– Windows program voluntarily yields control at
certain times (Windows 4 and 6.2)
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Windows NT Processes ([6])
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Executable program (code and data)
Private virtual address space
System resources (semaphores, ports, etc)
Process ID
Threads
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Windows NT Threads ([6])
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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
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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
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Windows NT PCB ([6])
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Executive (EPROCESS) blocks
ETHREAD blocks
Process Environment Block (PEB)
Thread Environment Block (TEB)
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Windows NT Fibers ([6])
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NT 3.51
Subsets of threads
“Lightweight” threads
User level threads
Scheduled to run by programmers not OS
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Windows NT Process States ([6])
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Ready
Standby – Next to run
Running
Waiting
Transition – Ready to run but kernel stack
paged out
• Terminated
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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.
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Windows NT Thread Scheduling ([6])
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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.
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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
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Windows NT Priorities ([6])
• Default base priority level within class
• Thread has base and current priority
• Priorities raised (1-15 range never above)
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After wait state
Entering wait state
Threads not getting CPU time
Priority goes down after each quantum until
base is reached
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IPC([3],[4],[7])
• Windows 95
– Thunking:
• Allows 16bit modules to communicate with 32bit
• Routine that maps addresses
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IPC (cont’d)
• Messages
– Queue per thread
• Semaphores
– Win16 mutex
– Used to prevent to Win16 applications from
executing the same code
– Ignored by Win32 applications
– Limits multitasking
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IPC (cont’d)
• Clipboard
– Actually shared memory
• OLE (Object Linking and Embedding)
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Windows 95
Drag & Drop
Enhancement to DDE
Embed or link data from one application to another.
Link – pointer to data
Embed – actually move
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IPC (cont’d)
• DDE (Dynamic Data Exchange)
– Windows 3.1
– Protocol that allows Windows applications to
share data.
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IPC (cont’d)
• 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
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References
1.
2.
3.
4.
5.
6.
7.
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, AddisonWesley, 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.
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