386 Central processing unit
Intel 80386 DX, 33 MHz, foreground
Produced:	From 1986 to Sept. 2007
Common manufacturers: Intel AMD IBM
Max CPU clock:	16 MHz to 40 MHz
Min feature size:	1. International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. 5 µm to 1 µm
Instruction set:	x86 (IA-32)
Cores:	1
Socket:	132-pin PGA, 132-pin PQFP; SX variant: 100-pin PQFP

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. A micrometre ( American spelling: micrometer; symbol µm) is one millionth of a Metre, or equivalently one thousandth of a Millimetre An instruction set is a list of all the instructions and all their variations that a processor can execute See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal IA-32 ( Intel Architecture 32-bit) often generically called X86 or x86-32, is the Instruction set architecture of Intel A multi-core processor (or chip-level multiprocessor, CMP) combines two or more independent cores into a single package composed of a single Integrated A pin grid array, often abbreviated PGA, refers to the arrangement of pins on the integrated circuit packaging PQFP, or plastic quad flat pack, is a type of IC packaging It has generally been superseded by the thinner TQFP package PQFP, or plastic quad flat pack, is a type of IC packaging It has generally been superseded by the thinner TQFP package A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated During its design phase the processor was code-named simply P3, the third-generation processor in the x86 line. See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal The 80386 operated at about 5 million instructions per second (MIPS) to 11. Instructions per second (IPS is a measure of a Computer 's processor speed 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. See also X86 assembly language The generic term x86 refers to the most commercially successful Instruction set architecture in the history of Personal The range of Integer values that can be stored in 32 bits is 0 through 4294967295 or −2147483648 through 2147483647 using Two's complement encoding Successively newer implementations of this same architecture have become literally several hundred times faster than the original i386 chip during these years.

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. In Computer science, concurrency is a properties of system in which several Computational processes are executing at the same time and potentially interacting Multi-user is a term that defines an Operating system or Application software 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. An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination 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 that have their Main memory divided into pages, paging (sometimes called swapping) is a transfer A gigabyte (derived from the SI prefix Giga-) is a unit of Information or Computer A terabyte (derived from the prefix Tera- and commonly abbreviated TB) is a measurement term for data storage capacity. Virtual memory is a Computer system technique which gives an application program the impression that it has contiguous working memory while in fact it may be physically Typical PC hardware A typical Personal computer consists of a case or chassis in a tower shape (desktop and the following parts Motherboard In the 80386 Microprocessor and later Virtual 8086 mode, also called virtual real mode or VM86, allows the execution of Real mode In Electronics design, tape-out or tapeout is the final stage of the Design cycle of Integrated circuits or Printed circuit boards 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. A motherboard is the central or primary Printed circuit board (PCB making up a complex electronic system such as a modern Computer or Laptop 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. A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated Compaq Computer Corporation was an American Personal computer company founded in 1982 and is now a brand name of Hewlett-Packard. Andrew Stephen Grove (Gróf András István (born 2 September 1936) is a Hungarian - American Businessman and scientist Single source publishing, also known as single sourcing, allows the same content to be used in different documents or 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. IA-32 ( Intel Architecture 32-bit) often generically called X86 or x86-32, is the Instruction set architecture of Intel

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 personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated An embedded system is a special-purpose Computer system designed to perform one or a few dedicated functions often with Real-time computing constraints This article is about the field of research and industry for the corporation see The Aerospace Corporation Aerospace comprises the

Architecture

The processor was a significant evolution in a long line of processors that stretched back to the Intel 8008. The Intel 8008 was an early byte-oriented Microprocessor designed and manufactured by Intel and introduced in April 1972 The predecessor of the 80386 was the Intel 80286, a 16-bit processor with a segment-based memory management and protection system. The Intel 286, introduced on February 1, 1982, (originally named 80286, and also called iAPX 286 in the programmer's manual In computing memory segmentation is one of the most common ways to achieve Memory protection; another common one is Paging. 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. The range of Integer values that can be stored in 32 bits is 0 through 4294967295 or −2147483648 through 2147483647 using Two's complement encoding In Computer Operating systems that have their Main memory divided into pages, paging (sometimes called swapping) is a transfer Virtual memory is a Computer system technique which gives an application program the impression that it has contiguous working memory while in fact it may be physically

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. In computing protected mode, also called protected virtual address mode, is an operational mode of X86 -compatible Central processing units (CPU Finally, the virtual 8086 mode (or VM86) made it possible to run one or more real mode programs in a protected environment. In the 80386 Microprocessor and later Virtual 8086 mode, also called virtual real mode or VM86, allows the execution of Real mode Real mode, also called real address mode, 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. The Intel 486, otherwise known as the 80486 i486 or just 486 was the first tightly pipelined X86 design The Pentium brand refers to Intel 's single-core x86 Microprocessor based on the P5 fifth-generation Microarchitecture. In computer systems design a flat memory model refers to a linear addressing Paradigm, such that the CPU can directly (and sequentially address all of the available x86-64 is a Superset of the x86 instruction set architecture.

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). Compaq Computer Corporation was an American Personal computer company founded in 1982 and is now a brand name of Hewlett-Packard. The Intel 8088 is an Intel X86 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 and introduced on the market in 1978 which gave rise to the X86 architecture 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 Motorola 68000 is a 16/32-bit CISC Microprocessor core designed and marketed by Freescale Semiconductor (formerly Motorola Semiconductor 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). A coprocessor is a Computer processor used to supplement the functions of the primary processor (the CPU The Intel 80387 ( 387 or i387) was the math Coprocessor for the 80386 series of Microprocessors and the first Intel In Computing, floating point describes a system for numerical representation in which a string of digits (or Bits represents a Real number.

i386SL

Intel i386 SL processor inside an Acer notebook

The i386SL was introduced as an alternative processor for laptop computers. A laptop computer, also known as a notebook computer, is a small Personal computer designed for mobile use. The processor offered several power management options (e. g. SMM), as well as different "sleep" modes to conserve battery power. System Management Mode (SMM is an operating mode first released with the Intel 386SL and available in later Microprocessors in the X86 architecture, in In electronics a battery is a combination of two or more Electrochemical cells which store chemical Energy which can be converted into electrical energy It also contained support for an external cache of 16 to 64 KB. In Computer science, a cache (kæʃ like "cash") is a collection of data duplicating original The extra functions caused this variant to have over 3 times as many transistors as the i386DX. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals The i386SL was first available at 20 MHz clockspeed [4], with the 25 MHz model later added. [5]

Embedded variants

An embedded version of the i386SX was produced as the i376. The Intel 80376, introduced January 16, 1989, was a variant of the Intel 80386SX intended for Embedded systems. This was later superseded by the i386EX, which was used in space applications such as the Hubble Space Telescope. The Intel 80386EX ( 386EX) is a variant of the Intel 386 Microprocessor designed for Embedded systems Introduced in August 1994 The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into

The AMD Am386DX-40

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. Compaq Computer Corporation was an American Personal computer company founded in 1982 and is now a brand name of Hewlett-Packard. International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology 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. Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer

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. Single source publishing, also known as single sourcing, allows the same content to be used in different documents or in various formats 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. The Am386 CPU was released by AMD in 1991. A 100%-compatible clone of the Intel 80386 design it sold millions of units Later Cyrix offered Cx486SLC and Cx486DLC processors, pin-compatible with 80386SX and 80386DX respectively. Cyrix was a CPU manufacturer that began in 1978 in Richardson Texas as a specialist supplier of high-performance math co-processors for 286 and Cyrix Cx486SLC was Cyrix 's first CPU offering released after years of selling Coprocessors that competed with Intel's units and offered better Cyrix Cx486DLC was an early 486 CPU from Cyrix, intended to compete with the Intel 486SX and DX

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 BIT 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. RapidCAD is a specially packaged Intel 486DX and a dummy Floating point unit (FPU designed as pin-compatible replacements for an Intel 80386 processor 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%.

References

External links

• Microprocessor Hall of Fame. Intel. Retrieved on 2007-08-11. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 2492 BC - Traditional date of the defeat of Bel by Hayk, progenitor and founder of the Armenian nation
• Intel 80386 Programmer's Reference Manual 1986 (PDF)
• Intel 80386 Programmer's Reference 1986
• CPU-INFO: 80386, indepth processor history
• Intel 386 manuals