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Intel 80386 Reference Programmer's Manual

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Intel 80386

<Processor> (Commonly abbreviated to "386", trademark "Intel386") The successor to the Intel 80286 microprocessor It was the first Intel processor with 32-bit data and address busses called IA-32. It can address four gigabytes (2^32 bytes) of memory; however, 16 megabytes is a typical maximum in IBM PCs. The 386 allows multiple application programs to run at the same time (when running under 386-specific operating systems) using " protected mode".

The 80386 initially shipped at 16 MHz in October 1985, making it faster than any Intel version of the 80286. Note, some others had overclocked 286 Processers up to 20Mhz.
The first IBM compatible to use the 386 was the Compaq 386, The 80386 had a MIPS (million instructions per second) rating of 5 (at 16 MHz) to 11.4 (33 MHz). This is an average of 0.33 MIPS per MHz of clock speed. <Byte magazine May93>   This indicated the 386 is up to 50% more powerful than the 0.21 MIPS/MHz rating of the 80286, although MIPS is not always a reliable pedictor of CPU performance.

It did not require special EMS memory boards to expand MS-DOS memory limits like the 80286 did. With the 386, the EMS standard can be simulated in normal extended memory, and many DOS add-ons provide this "Expanded Memory Manager" feature. This was the first X86 processor that could eliminate the 64K memory segmentation issued that programmers had to deal with

Some of the first operating systems to support the 386 processor was Bill Jolitz's 386BSD, BSDI's BSD386, Bill evans's Minix 386, and Linux. Then Microsoft Windows 3.1 .

Intel 80386 Reference Programmer's Manual

Chapter 1 -- Introduction to the 80386

Chapter 2 -- Basic Programming Model

Chapter 3 -- Applications Instruction Set

Part II Systems Programming

Chapter 4 -- Systems Architecture

Chapter 5 -- Memory Management

Chapter 6 -- Protection

Chapter 7 -- Multitasking

Chapter 8 -- Input/Output

Chapter 9 -- Exceptions and Interrupts

Chapter 10 -- Initialization

Chapter 11 -- Coprocessing and Multiprocessing

Chapter 12 -- Debugging

Part III Compatibility

Chapter 13 -- Executing 80286 Protected-Mode Code

Chapter 14 -- 80386 Real-Address Mode

Chapter 15 -- Virtual 8086 Mode

Chapter 16 -- Mixing 16-Bit and 32 Bit Code

Part IV Instructions Set

Chapter 17 -- 80386 Instruction Set