Window 3 Learner
Window- 3 Learner
Features:
Windows 3.0 includes a Protected/Enhanced mode which allows
Windows applications to use morememory in a more painless manner than their DOS
counterparts could. It can run in any of Real, Standard, or 386 Enhanced modes,
and is compatible with any Intel processor from the 8086/8088 up
to 80286
and 80386.Windows 3.0 tries to auto detect which mode to run in, although it can be
forced to run in a specific mode using the switches:
/r (real mode),
/s ("standard"
286 protected mode) and /3 (386
enhanced protected mode) respectively. Since Windows 3.0 (and later Windows 3.1) runs in 16-bit 286 protected mode and
not 32-bit 386 protected mode, the default setup is to use the 64 KB
segmented memory model. However, on 32-bit CPUs, the programmer had access to
larger memory pointers and so it was possible to expand program segments to
whatever size was desired (the maximum limit being 16 MB due to segment
descriptors being 24-bit). Since Windows
API functions were 16-bit at the time, they could not use 32-bit pointers
and thus it was necessary to place the portion of the program code that
performed OS calls in a 64 KB segment,like
in DOS, although 32-bit instructions may be contained in the code.(Ami Pro was the
first Windows application to require a 386). Because of this, Windows 3.0 can
access only 16 MB total of RAM, even on 386 or higher CPUs which have a
theoretical capability of utilizing 4GB.
Memory modes
Windows 3.0 was the only version of
Windows that could be run in three different memory modes:
- Real mode,
intended for older computers with a CPU below Intel 80286, and corresponding to its real mode;
- Standard mode,
intended for computers with an 80286 processor, and corresponding to its protected mode;
- 386 Enhanced mode,
intended for newer computers with an Intel 80386 processor or above, and
corresponding to its protected mode and virtual 8086 mode.[12]
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