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Windows 3.x

Windows 3.x. Umbrella term for Windows 3.0, 3.1, Windows for Workgroups, etc. Win 3.x is just an operating environment that runs on top of DOS (unlike 95, which is also an operating system) Like DOS, Windows 3.x filenames are limited to 8 + 3 characters

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Windows 3.x

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  1. Windows 3.x • Umbrella term for Windows 3.0, 3.1, Windows for Workgroups, etc. • Win 3.x is just an operating environment that runs on top of DOS (unlike 95, which is also an operating system) • Like DOS, Windows 3.x filenames are limited to 8 + 3 characters • Icons are arranged in group files (.GRP) • each group file represents contents of one window

  2. Windows 3.x core files • KRNL386.EXE • controls how programs use memory and IO • loads and executes Windows applications • USER.EXE - user interface • creates and controls onscreen windows (moving, resizing, deleting windows) • I/O through mouse, keyboard, COM ports • GDI.EXE- Windows GUI • graphics on screen

  3. Windows 3.x INI files • .INI files are used to initialize Windows • plain text files, can be edited in text editor • SYSTEM.INI • identifies device drivers • only INI file that actually needs to be present in order to load Windows 3.x • key sections of the SYSTEM.INI file are the [Boot], [Keyboard], [Drivers], and [386enh] sections.

  4. Windows 3.x INI files • WIN.INIcontrols desktop appearance and file associations • PROGMAN.INI defines desktop windows • Others: (less important) • CONTROL.INI- set colors and background patterns • MOUSE.INI- mouse hardware settings • PROTOCOL.INI- networking on Windows for Workgroups

  5. HIMEM.SYS • HIMEM.SYS is the device driver for accessing memory above 640K (expanded and extended memory) • HIMEM.SYS also creates High Memory Area (HMA): a 64KB area of memory above the 1MB address space • With HIMEM.SYS, can use DOS=HIGH statement to shift portions of DOS from conventional memory into the HMA.

  6. HIMEM.SYS cont. • For Windows 3.x to run, HIMEM.SYS must be loaded in CONFIG.SYS • HIMEM.SYS should be listed in the CONFIG.SYS file before any other memory managers or device drivers.

  7. Windows 3.x modes • real mode- 8086 mode- now obsolete • runs in DOS limit of 1 MB RAM • standard mode - 286 protected mode • could address up to 16 MB memory • can only run 1 DOS program at a time • 386 enhanced - 386 protected mode • can address up to 4 GB RAM • supports virtual memory • can run multiple DOS programs at same time

  8. Win 3.x and virtual memory • Windows 3.x in 386 protected mode supports virtual memory (unlike DOS) • Virtual memory: allows CPU to use part of hard drive to simulate extra memory- • swap file: the part of the hard drive that thinks its RAM- (see Meyers 576-580) • functions as a temporary storage area • kicks in only when you run out of RAM • swapping in and out slows system down

  9. Windows 3.x swap files • Two types of swap files: • Temporary virtual swap file • WIN386.SWP • only exists when Windows is running, erased when exit Windows • permanent swap file • 386SPART.PAR • never erased

  10. Win3.x: Cooperative multitasking • Win 3.x uses cooperative multitasking • OS transfers control to the various applications, which “cooperate” with each other to share control of the system. • 1. OS gives control to the running application • 2. When the application completes its task, it gives control back to the OS • 3. OS then gives control to the next scheduled application.

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