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

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

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.

Windows 3.x INI files WIN.INI controls 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

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.

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.

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

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

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

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.