| 3. Windows 3.1 & Windows 95 | ||
|---|---|---|
 | Chapter 7. Parallel Machines |  |
| 3. Windows 3.1 & Windows 95 | ||
|---|---|---|
| | Chapter 7. Parallel Machines | |
Windows 3.1
Protected mode.
32 bit VMM (Virtual Machine Manager).
Win386.exe.
VxVs Virtual device drivers
GDI Graphical Devices Interface
User Windows Management
DLLs that provide OS services run in this same memory space.
If one App crashes all system crashes.
Windows 95
1 sample
protected mode
32 bit VMM (Virtual Machine Manager)
Win 32 App Run preemptive in private address space.
Differences form Windows 3.1
Provides address space for Win 32 process
Add support for threads within Win 32 Apps
It loads each win 32 App into System VM
Win 32 can write to critical areas of the OS (upper 2GB lower 1MB)
VMM schedule is preemptive but calls to 16 bit can block the system
16 bit App run cooperatively
When a 16 bit program executes all other programs can't run 16 bit code calls until it "yields" control. Win 32 apps will block if they need Win 16 calls.
Apps run in user mode kernel runs in kernel mode but sensitive areas can not be protected to allow writes by 16 bit win apps.
| |  | |
| 2. Mach Kernel |  | 4. Windows NT |
