The Intel 80386, otherwise known as the Intel386, i386 or just 386, is a microprocessor which has been used as the central processing unit (CPU) of many personal computers since 1986. During its design phase the processor was code-named simply P3, the third-generation processor in the x86 line. The 80386 operated at about 5 million instructions per second (MIPS) to 11.4 MIPS for the 33 MHz model. [1] It was the first x86 processor to have a 32-bit architecture, with a basic programming model that has remained virtually unchanged for over twenty years and remains completely backward compatible. Successively newer implementations of this same architecture have become literally several hundred times faster than the original i386 chip during these years. Alexei Shulgin, born 1963 in Moscow, Russia, is a contemporary artist. ... CPU redirects here. ... Image File history File links No higher resolution available. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Advanced Micro Devices, Inc. ... For other uses, see IBM (disambiguation) and Big Blue. ... CPU redirects here. ... This article is about the SI unit of frequency. ... This article is about the SI unit of frequency. ... The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is by far the most common field-effect transistor in both digital and analog circuits. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... An instruction set is (a list of) all instructions, and all their variations, that a processor can execute. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... It has been suggested that this article or section be merged with X86 assembly language. ... Diagram of an Intel Core 2 dual core processor, with CPU-local Level 1 caches, and a shared, on-die Level 2 cache. ... Package Diagram for 168-Pin PGA Embedded IntelDX2™ Processor The pin grid array or PGA is a type of packaging used for integrated circuits, particularly microprocessors. ... A microprocessor incorporates most or all of the functions of a central processing unit (CPU) on a single integrated circuit (IC). ... CPU redirects here. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... Instructions per second (IPS) is a measure of a computers processor speed. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ...

It was designed with several very impressive features:

1. run multiple concurrent multi-user multitasking operating systems ( see here)
2. page 4GB of memory from 64TB of virtual memory
3. hardware debugging support
4. Virtual 8086 mode

Designed and manufactured by Intel, the i386 processor was taped-out (1000 nm) in October of 1985. Intel decided against producing the chip before that date, as the cost of production would have been uneconomical. Full-function chips were first delivered to customers in 1986. Mainboards for 386-based computer systems were highly elaborate and expensive to produce, but were rationalized upon the 386's mainstream adoption. The first personal computer to make use of the 386 was designed and manufactured by Compaq[2], and Andy Grove, Intel's CEO at the time, made the decision to single-source the processor, a decision that was ultimately crucial to both the processor's and Intel's success in the market. The Dining Philosophers, a classic problem involving concurrency and shared resources In computer science, concurrency is a property of systems in which several computational processes are executing at the same time, and potentially interacting with each other. ... Multi-user is a term that defines an operating system that allows concurrent access by multiple users of a computer. ... In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ... The Popek and Goldberg virtualization requirements are a set of sufficient conditions for a computer architecture to efficiently support system virtualization. ... In computer operating systems, paging memory allocation, paging refers to the process of managing program access to virtual memory pages that do not currently reside in RAM. It is implemented as a task that resides in the kernel of the operating system and gains control when a page fault takes... This article is about the unit of measurement. ... RAM redirects here. ... This article is about a measurement term for data storage capacity. ... This article is about the computer term. ... Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. ... Debugging is a methodical process of finding and reducing the number of bugs, or defects, in a computer program or a piece of electronic hardware thus making it behave as expected. ... In the 80386 and later, Virtual 8086 mode, also called virtual real mode (or VM86), allows the execution of real mode applications that violate the rules under the control of a protected mode operating system. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... In electronics, tape-out is the name of the final stage of the design of an integrated circuit such as a microprocessor, the point at which the description of a circuit is sent for manufacture. ... The ABIT KT7, an ATX format motherboard A motherboard is a printed circuit board used in a personal computer. ... Compaq Computer Corporation is an American personal computer company founded in 1982, and now a brand name of Hewlett-Packard. ... Dr. Andrew Stephen Grove (born September 2, 1936 in Budapest, Hungary) is an American businessman. ... Single source publishing or single sourcing allows the same content to be used in different documents and in various formats. ...

The range of processors compatible with the 80386 is often collectively termed x86 or the i386 architecture; today, Intel prefers the name IA-32 however. It has been suggested that this article or section be merged with X86 assembly language. ...

In May 2006 Intel announced that production of the 386 would cease at the end of September 2007. [3] Although it had long been obsolete as a personal computer CPU, Intel, and others, had continued to manufacture the chip for embedded systems, including aerospace technology. A router, an example of an embedded system. ... Look up aerospace in Wiktionary, the free dictionary. ...

Architecture

The processor was a significant evolution in a long line of processors that stretched back to the Intel 8008. The predecessor of the 80386 was the Intel 80286, a 16-bit processor with a segment-based memory management and protection system. The 80386 added a 32-bit architecture and a paging translation unit, which made it much easier to implement operating systems which used virtual memory. Intel 8008 The Intel 8008 was an early microprocessor designed and manufactured by Intel and introduced in April, 1972. ... AMD 80286 at 12 MHz. ... In computer science, 16-bit is an adjective used to describe integers that are at most two bytes wide, or to describe CPU architectures based on registers, address buses, or data buses of that size. ... On the Intel x86 architecture, a memory segment is the portion of memory which may be addressed by a single index register without changing a 16-bit segment selector. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... In computer operating systems, paging memory allocation, paging refers to the process of managing program access to virtual memory pages that do not currently reside in RAM. It is implemented as a task that resides in the kernel of the operating system and gains control when a page fault takes... This article is about the computer term. ...

The 80386 featured three operating modes: real mode, protected mode and virtual mode. The protected mode allowed the use of all the possibilities of the 286 and the protected mode extension of the 386, especially addressing up to 4 GB of memory. Finally, the virtual 8086 mode (or VM86) made it possible to run one or more real mode programs in a protected environment. Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... GB may stand for: // Gordon Brown, the new British Prime Minister George W. Bush, the US President Gb (digraph), a digraph in the Latin alphabet Government and binding, theory by Noam Chomsky Sarin, nerve gas (NATO designation: GB) Gigabit (symbol: Gb or Gbit) Gigabyte (symbol: GB) Game Boy line, a... In the 80386 and later, Virtual 8086 mode, also called virtual real mode (or VM86), allows the execution of real mode applications that violate the rules under the control of a protected mode operating system. ... Real mode (also called real address mode in Intels manuals) is an operating mode of 80286 and later x86-compatible CPUs. ...

The 386DX architecture.

Though Intel would shortly introduce the 80486 and eventually the Intel Pentium line of processors, the support in the 386 for the 32-bit flat memory model would arguably be the most important feature change for the x86 processor family until AMD released x86-64 in 2003. Image File history File links Download high resolution version (1409x994, 66 KB) The 386DX architecture. ... Image File history File links Download high resolution version (1409x994, 66 KB) The 386DX architecture. ... The Intel486[1] brand refers to Intels family of i486 (incl. ... Pentium MMX - top view The Pentium is a fifth-generation x86 architecture microprocessor by Intel which first shipped on March 22, 1993. ... In computer programming, the flat memory model is an approach to organizing memory address space. ... Advanced Micro Devices, Inc. ... The AMD64 or x86-64 is a 64-bit processor architecture invented by AMD. It is a superset of the x86 architecture, which it natively supports. ...

i386SX

The Intel 80386SX processor of a Compaq Deskpro Computer

Later in the i386's production run, Intel introduced the i386SX (internally codenamed P9), which was meant to be a low cost version of the 386 line (a similar situation to the introduction of the 8088 chip, used in the original IBM PC, which was a lower cost version of the 8086). The SX series of chips was 32-bit internally, but had a 16-bit external data bus and a 24 bit address bus; therefore, the processor could only address 16 MB of memory (similar to a Motorola 68000). The original i386 was subsequently renamed the i386DX to avoid confusion. Neither CPU included a math coprocessor (most mainboards included a socket for an i387), though the naming would cause some head-scratching later when the i486 came in a DX variant that did include floating-point capability (which was physically present but disabled in early i486SXs). Compaq Computer Corporation is an American personal computer company founded in 1982, and now a brand name of Hewlett-Packard. ... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... The 8086 is a 16-bit microprocessor chip designed by Intel in 1978, which gave rise to the x86 architecture. ... MB, Mb, mB or mb may mean: Mb (digraph) Megabit (1,000,000 bits) or mebibit (220 = 1,048,576 bits); the preferred symbols are Mb and Mibit, respectively¹ Megabyte (1,000,000 bytes) or mebibyte (220 = 1,048,576 bytes); the preferred symbols are MB and MiB, respectively¹ MB... The Motorola 68000 is a CISC microprocessor, the first member of a successful family of microprocessors from Motorola, which were all mostly software compatible. ... This article or section does not cite its references or sources. ... The Intel 80387 (387) was the math coprocessor for the Intel 80386 series of microprocessors. ... This article or section is in need of attention from an expert on the subject. ...

i386SL

Intel i386 SL processor inside an Acer notebook

The i386SL was introduced as an alternative processor for laptop computers. The processor offered several power management options (e.g. SMM), as well as different "sleep" modes to conserve battery power. It also contained support for an external cache of 16 to 64 KB. The extra functions caused this variant to have over 3 times as many transistors as the i386DX. The i386SL was first available at 20 MHz clockspeed [4], with the 25 MHz model later added. [5] Acer can refer to one of the following: For the company named Acer, see Acer (company). ... Laptop with touchpad. ... System Management Mode (SMM) is a mode of Intel x86 microprocessor in which all normal execution (including the operating system) is suspended, and special separate software (usually firmware or a hardware-assisted debugger) is executed in high-privilege mode. ... For other uses, see Battery. ... For other uses, see cache (disambiguation). ... The abbreviation KB or kb can refer to: kilobyte (kB or KB), equal to 1,000 bytes or 1024 bytes depending on context, or kibibyte (KiB), equal to 1,024 bytes. ... Assorted discrete transistors A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. ...

Embedded variants

An embedded version of the i386SX was produced as the i376. This was later superseded by the i386EX, which was used in space applications such as the Hubble Space Telescope. The Intel 80376, introduced January 16, 1989, was a variant of the Intel 80386 intended for embedded systems. ... The Intel 80386EX (386EX) is a variant of the Intel 386 microprocessor designed for embedded systems. ... The Hubble Space Telescope (HST; also known colloquially as the Hubble or just Hubble) is a space telescope that was carried into Earth orbit by the Space Shuttle in April 1990. ...

The AMD Am386DX-40

Image File history File linksMetadata Download high resolution version (670x609, 156 KB) AMD 386DX-40 CPU. Source/Photographer: Appaloosa 00:07, 20 November 2005 (UTC) File links The following pages link to this file: Intel 80386 Metadata This file contains additional information, probably added from the digital camera or scanner... Image File history File linksMetadata Download high resolution version (670x609, 156 KB) AMD 386DX-40 CPU. Source/Photographer: Appaloosa 00:07, 20 November 2005 (UTC) File links The following pages link to this file: Intel 80386 Metadata This file contains additional information, probably added from the digital camera or scanner...

Business importance

The first PC company to design and manufacture a PC based on the 386 was Compaq, rather than IBM, which had been dominant until that time. IBM was offered use of the processor, but relied instead on earlier processors to which it had manufacturing rights. The success of the Compaq 386 PC played an important role in legitimizing the PC "clone" industry, and to establishing Intel (and Microsoft) as central component suppliers to it. Compaq Computer Corporation is an American personal computer company founded in 1982, and now a brand name of Hewlett-Packard. ... For other uses, see IBM (disambiguation) and Big Blue. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ...

From a business perspective, the i386 was significant because it was the first significant microprocessor to be single-sourced – it was available only from Intel Corp. Prior to this, the difficulty of making chips and the uncertainty of reliable supply required that any mass-market semiconductor be multi-sourced, that is, made by two or more manufacturers, the second and subsequent ones manufacturing under license from the designer. Single-sourcing the i386 allowed Intel greater control over its development and substantially greater profits in later years. However, AMD introduced its compatible Am386 processor in March 1991 after overcoming legal obstacles, thus ending Intel's monopoly on 32-bit 386-compatible processors. Later Cyrix offered Cx486SLC and Cx486DLC processors, pin-compatible with 80386SX and 80386DX respectively. Single source publishing or single sourcing allows the same content to be used in different documents and in various formats. ... Advanced Micro Devices, Inc. ... AMD Am386DX-40 CPU The Am386 central processing unit microprocessor was released by AMD in 1991. ... Cyrix was a CPU manufacturer that began in 1988 in Richardson, TX as a specialist supplier of high-performance math co-processors for 286 and 386 systems. ... Cyrix Cx486SLC Microprocessor The Cyrix Cx486SLC was Cyrixs first CPU offering, released after years of selling coprocessors that competed with Intels units and offered better performance at a comparable or lower price. ... Cyrix Cx486DLC Microprocessor The Cyrix Cx486DLC was an early 486 CPU from Cyrix, intended to compete with the Intel 486SX and DX. Texas Instruments, who manufactured the 486DLC for Cyrix, also released its own version of the chip, the TI486SXL with 8kB internal cache vs 1kB of the original Cyrix...

Early Problems

Early in production, Intel found a bug that could cause a system to unexpectedly halt when running 32-bit software. Not all of the processors already manufactured were affected, so Intel tested its inventory. Processors that were found to be bug-free were marked with a double-sigma (ΣΣ), whilst affected processors were marked "16 BITS S/W ONLY" and sold as otherwise good-parts, since at the time 32 bit software was not relevant for most users. Such chips are now extremely rare.

Upgrades

Intel offered a modified version of its later 80486DX in 80386 packaging, branded as the Intel RapidCAD, to provide an upgrade path for 80386 users. The upgrade worked as a pair of chips that replaced both the 386 and 387, although since the 80486DX contained an FPU itself the chip that replaced the 387 served no purpose except to appear like a coprocessor, so that the system board would be configured correctly. The CAD branding can be explained by the massive increase in floating point performance offered, whilst integer performance increase was around 30%. RapidCAD is a specially packaged Intel 486DX and a dummy floating point unit (FPU) designed as pin-compatible replacements for an Intel 80386 processor and 80387 FPU. Since the DX variant has a working on-chip FPU, a dummy FPU package is supplied to go in the Intel 387 FPU... A floating point unit (FPU) is a part of a CPU specially designed to carry out operations on floating point numbers. ...

References

External links

• Microprocessor Hall of Fame. Intel. Retrieved on 2007-08-11.
• Intel 80386 Programmer's Reference Manual 1986 (PDF)
• Intel 80386 Programmer's Reference 1986
• CPU-INFO: 80386, indepth processor history
• Intel 386 manuals