When Compaq introduced the first PC based on Intel's new 80386 microprocessor, the Compaq Deskpro 386, in 1986, it marked the first CPU change to the PC platform that was not initiated by IBM.

This was a version of Windows 2. 1 adapted for the 80386 processor.

All Windows and DOS-based applications at the time were real mode, running over the protected mode kernel by using the virtual 8086 mode, which was new with the 80386 processor.

Windows 3. 0 could run in real, standard, or 386 enhanced modes, and was compatible with any Intel processor from the 8086 / 8088 up to the 80286 and 80386.

IA-32 ( Intel Architecture, 32-bit ), also known as x86-32, i386 or x86, is the CISC instruction-set architecture of Intel's most commercially successful microprocessors, and was first implemented in the Intel 80386 as a 32-bit extension of x86 architecture.

The IA-32 instruction set was introduced in the Intel 80386 microprocessor in 1986 and remains the basis of most PC microprocessors over twenty years later.

In theory, real-mode applications could be directly executed in 16-bit protected mode if certain rules were followed ; however, as many DOS programs broke those rules, protected mode was not widely used until the appearance of its successor, the 32-bit Intel 80386, which was designed to go back and forth between modes easily.

The Intel 80386, also known as the i386, or just 386, was a 32-bit microprocessor introduced by Intel in 1985.

A 33 MHz 80386 was reportedly measured to operate at about 11. 4 MIPS.

The first personal computer to make use of the 80386 was designed and manufactured by Compaq and marked the first time a fundamental component in the IBM PC compatible de facto-standard was updated by a company other than IBM.

The predecessor of the 80386 was the Intel 80286, a 16-bit processor with a segment-based memory management and protection system.

Chief architect in the development of the 80386 was John H. Crawford.

He was responsible for extending the 80286 architecture and instruction set to 32-bit, and then led the microprogram development for the 80386 chip.

The original 80386 was subsequently renamed i386DX to avoid confusion.

The first company to design and manufacture a PC based on the Intel 80386 was Compaq.

IBM was offered use of the 80386, but had manufacturing rights for the earlier 80286.

The i387 math coprocessor was not ready in time for the introduction of the 80386, and so many of the early 80386 motherboards instead provided a socket and hardware logic to make use of an 80287.

The upgrade was a pair of chips that replaced both the 80386 and 80387.

The Intel 80486 microprocessor ( alias i486 or Intel486 ) was a higher performance follow up on the Intel 80386.

It was moved to the 80386 machine types in 1994, and exists today as Windows / XP and Linux implementations.

Work on porting 4. 3BSD-Reno and later 4. 3BSD Net / 2 to the Intel 80386 was done for the University of California by William Jolitz at Berkeley.

Newer microprocessor chips such as the Motorola 68000 ( 1979 ) and Intel 80386 ( 1985 ) also included 32-bit logical addressing.

Due to their lagging performance ( 2. 5 Mbit / s ), these devices have been largely obsolete since the advent of the 80386 processor in 1985 and its capacity for 32-bit transfers.

Protected mode was first added to the x86 architecture in 1982, with the release of Intel's 80286 ( 286 ) processor, and later extended with the release of the 80386 ( 386 ) in 1985.

On the x86 architecture, a 32-bit application normally means software that typically ( not necessarily ) uses the 32-bit linear address space ( or flat memory model ) possible with the 80386 and later chips.

The 80386 could correctly execute most code intended for earlier 16-bit x86 processors such as the 8088 and 80286 that were ubiquitous in early PCs.

The 80486 and P5 Pentium line of processors were descendants of the 80386 design.

The AT and 80286-based systems were generally socketed for the 80287, and 80386 / 80386SX based machines for the 80387 and 80387SX respectively, although early ones were socketed for the 80287, since the 80387 did not exist yet.

Even after PCs broke the 640 KB limit with the 80286, special programming techniques were required to address significant amounts of memory until the 80386, as opposed to other 32-bit processors such as SPARC which provided straightforward access to nearly their entire 4 GB memory address range.

Compaq ) and then the VESA Local Bus Standard, were late 1980s expansion buses that were tied but not exclusive to the 80386 and 80486 CPU bus.

Microsoft Fortran and the first 32 bit compiler for 80386 were also part of this project.

DESQview really came into its own on Intel 80386 machines which were better at utilizing memory above DOS's limit.

With the introduction of the 80386, the memory management features were enhanced to allow the system to be shifted into protected mode but also allowing the addresses to be configured in a virtual 8086 mode so that the extended memory could be mapped into addressing frames and accessible to real-mode programs such as MS-DOS.

DOS extenders were initially developed in the 1980s following the introduction of the Intel 80286 processor ( and later expanded upon with the Intel 80386 ), to cope with the memory limitations of MS-DOS and its derivatives.

The original accounts were all dialup shell accounts on Xenix Intel 80386 Tandy PC's, with email addresses in the format of user @ netcom. com.

Generation 2 competed against the 80386 ( the first 32-bit x86 processor ), and generation 3 against the 80486.

IBM's first priority based pre-emptive multitasking, graphical, windows based, object oriented operating system for the Intel 80386 that included virtual 8086 mode and full 32 bit support and released in 1992.

Virtual 8086 mode, introduced with the Intel 80386, allows the A20 wrap-around to be simulated by using the virtual memory facilities of the processor: physical memory may be mapped to multiple virtual addresses thus allowing the memory mapped at first mebibyte of virtual memory may be mapped again in the second mebibyte of virtual memory.

The mechanism is first described in section 9. 8. 13 in the Intel 80386 programmer's reference manual from 1986.

CEMM, for Compaq Expanded Memory Manager was the first so-called PC " memory manager " for Intel 80386 CPUs, able to transform " XMS " extended memory into " EMS " expanded memory by using the virtual memory features and the virtual 8086 mode of the CPU.

It was one of the first compilers to support the Intel 80386 " protected mode ".