i386

Development of i386 technology began in 1982 under the internal name of P3.{{cite magazine |last=Gomes |first=Lee |date=November–December 1985 |title=Behind the Scenes: The Making of the 386. |issue=Special 32-Bit Issue: "A Well-Bred Classic: The 80386" |magazine=Solutions |publisher=Intel Corporation |editor-last=Rant |editor-first=Jon |page=19}} The tape-out of the 80386 development was finalized in July 1985. The 80386 was introduced as pre-production samples for software development workstations in October 1985.{{cite journal | last=Goering | first=Richard | title=Development Tools Support 80386 Applications | url=https://books.google.com/books?id=60A-AQAAIAAJ&q=%22Valid+Logic%22+80386+%22Daisy%22 | date=December 1985 | journal=Computer Design | publisher=PennWell | volume=24 | issue=17 | pages=33–34 | access-date=October 14, 2021 | via=Gale OneFile}} Manufacturing of the chips in significant quantities commenced in June 1986,{{Cite magazine | last = Forbes | first = Jim | title = Development of 386 Accelerating |magazine= InfoWorld | volume = 8 | issue = 4 | page =5 | publisher = InfoWorld Media Group| date = January 27, 1986 | url = https://books.google.com/books?id=my8EAAAAMBAJ&pg=PA5 | issn = 0199-6649 }} Introduced October 1985, production chip in June 1986.{{Cite magazine | last = Ranney | first = Elizabeth | title = ALR Hopes to Beat Completion With Fall Release of 386 Line |magazine= InfoWorld | volume = 8 | issue = 35 | page =5 | publisher = InfoWorld Media Group| date = September 1, 1986| url = https://books.google.com/books?id=cS8EAAAAMBAJ&pg=PA5| issn = 0199-6649}} The first 80386 computers were released around October 1986. along with the first plug-in device that allowed existing 80286-based computers to be upgraded to the 386, the Translator 386 by American Computer and Peripheral.{{cite journal | last=Whitmore | first=Sam | title=Product Lets Users Write Software for 80386 at Low Cost | url=https://link.gale.com/apps/doc/A4280128/GPS | date=June 17, 1986 | journal=PCWeek | publisher=Ziff-Davis | volume=3 | issue=24 | page=11 | access-date=October 14, 2021 | via=Gale OneFile}}{{cite journal | last=Rhein | first=Bob | date=August 11, 1986 | url=https://archive.org/details/sim_mis-week_1986-08-11_7_32/page/38/ | title=ACP Is Readying 2 Boards | journal=MIS Week | volume=7 | issue=32 | page=38 | publisher=Fairchild Publications | via=the Internet Archive}} The 80386 being sole sourced made the CPU very expensive.{{Cite magazine |last=Marshall |first=Trevor |last2=Tazelaar |first2=Jane Morrill |date=February 1989 |title=Worth the RISC |url=https://archive.org/details/eu_BYTE-1989-02_OCR/page/n299/mode/2up?view=theater |access-date=2024-10-08 |magazine=BYTE |pages=245–249}} Mainboards for 80386-based computer systems were cumbersome and expensive at first, but manufacturing was justified upon the 80386's mainstream adoption. The first personal computer to make use of the 80386 was the Deskpro 386, designed and manufactured by Compaq;{{cite web |url=http://www.crn.com/crn/special/supplement/816/816p65_hof.jhtml|archive-url=https://web.archive.org/web/20090627055110/http://www.crn.com/crn/special/supplement/816/816p65_hof.jhtml |url-status=dead |archive-date=June 27, 2009 |title=CRN |date=June 27, 2009 |via=The Internet Archive |access-date=March 15, 2018}} this marked the first time a fundamental component in the IBM PC compatible de facto standard was updated by a company other than IBM.

The first versions of the 386 have 275,000 transistors. The 20 MHz version operates at 4–5 MIPS. It also performs between 8,000 and 9,000 Dhrystones per second.Intel Corporation, "New Product Focus Components: The 32-Bit Computing Engine Full Speed Ahead", Solutions, May/June 1987, page 10 The 25 MHz 386 version is capable of 7 MIPS.Lewnes, Ann, "Welcome 80386SX", Microcomputer Solutions, September/October 1988, page 2 A 33 MHz 80386 was reportedly measured to operate at about 11.4 and 11.5 MIPS.{{cite web |url=http://intel80386.com |title=Intel Architecure Programming and Information |website=intel80386.com |access-date=March 15, 2018}}Intel Corporation, "A Guide to the Intel Architecture", Microcomputer Solutions, January/February 1992, page 11 At that same speed, it has the performance of 8 VAX MIPS.Lewnes, Ann, "The Intel386 Architecture Here to Stay", Intel Corporation, Microcomputer Solutions, July/August 1989, page 2 These processors run about 4.4 clocks per instruction.Chen, Allan, "Designing a Mainframe on a Chip: Interview with the i486 Microprocessor Design Team", Intel Corporation, Microcomputer Solutions, July/August 1989, page 12

In May 2006, Intel announced that i386 production would stop at the end of September 2007.{{cite web |title=Intel cashes in ancient chips |url=http://www.reghardware.co.uk/2006/05/18/intel_cans_386_486_960_cpus/ |access-date=May 18, 2006 |archive-url=https://web.archive.org/web/20110813073335/http://www.reghardware.com/2006/05/18/intel_cans_386_486_960_cpus/ |archive-date=August 13, 2011 |url-status=dead}} Although it had long been obsolete as a personal computer CPU, Intel and others had continued making the chip for embedded systems. Such systems using an i386 or one of many derivatives are common in aerospace technology and electronic musical instruments, among others. Some mobile phones also used (later fully static CMOS variants of) the i386 processor, such as the BlackBerry 950{{cite web |url=http://the-gadgeteer.com/2001/02/26/rim_blackberry_950_review/ |title=RIM BlackBerry 950 Review |website=The Gadgeteer |date=February 26, 2001 |access-date=March 15, 2018}} and Nokia 9000 Communicator. Linux continued to support i386 processors until December 11, 2012, when the kernel cut 386-specific instructions in version 3.8.{{cite web |url=https://www.phoronix.com/scan.php?page=news_item&px=MTI0OTg |title=Linux Kernel Drops Support for Old Intel 386 CPUs |last=Larabel |first=Michael |website=Phoronix |date=December 12, 2012 |access-date=October 14, 2019}}

File:80386DX arch.png]]

|}

The processor was a significant evolution in the x86 architecture, and extended 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 three-stage instruction pipeline which it brought up to total of 6-stage instruction pipeline, extended the architecture from 16-bits to 32-bits, and added an on-chip memory management unit.Intel Corporation, "Extending the Legacy of Leadership: The 80386 Arrives", Special 32-Bit Issue Solutions, November/December 1985, page 2 This paging translation unit made it much easier to implement operating systems that used virtual memory. It also offered support for register debugging.

The 80386 featured three operating modes: real mode, protected mode and virtual mode. The protected mode, which debuted in the 286, was extended to allow the 386 to address up to 4 GB of memory. With the addition of segmented addressing system, it can expand up to 64 terabytes of virtual memory.Rant, Jon; "Extending the Legacy of Leadership: The 80386 Arrives", Intel Corporation, Special 32-Bit Issue Solutions, November/December 1985, page 2 The all new virtual 8086 mode (or VM86) made it possible to run one or more real mode programs in a protected environment, although some programs were not compatible. It features scaled indexing and 64-bit barrel shifter.Intel Corporation, "New Product Focus Component: A 32-Bit Microprocessor With A Little Help From Some Friends", Special 32-Bit Issue Solutions, November/December 1985, page 13

The ability for a 386 to be set up to act like it had a flat memory model in protected mode despite the fact that it uses a segmented memory model in all modes was arguably the most important feature change for the x86 processor family until AMD released the x86-64 in 2003.

Several new instructions have been added to 386: BSF, BSR, BT, BTS, BTR, BTC, CDQ, CWDE, LFS, LGS, LSS, MOVSX, MOVZX, SETcc, SHLD, SHRD.

Two new segment registers have been added (FS and GS) for general-purpose programs. The single Machine Status Word of the 286 grew into eight control registers CR0–CR7. Debug registers DR0–DR7 were added for hardware breakpoints. New forms of the MOV instruction are used to access them.

The chief architect in the development of the 80386 was John H. Crawford.{{cite web|url=http://www.intel.com/pressroom/kits/bios/crawford.htm |title=Intel Fellow—John H. Crawford |publisher=Intel.com |date=August 16, 2010 |access-date=September 17, 2010}} He was responsible for extending the 80286 architecture and instruction set to 32-bits, and then led the microprogram development for the 80386 chip.

The i486 and P5 Pentium line of processors were descendants of the i386 design.

The following data types are directly supported and thus implemented by one or more i386 machine instructions; these data types are briefly described here.:

• Bit (Boolean value), bit field (group of up to 32 bits) and bit string (up to 4 Gbit in length).
• 8-bit integer (byte), either signed (range −128..127) or unsigned (range 0..255).
• 16-bit integer, either signed (range −32,768..32,767) or unsigned (range 0..65,535).
• 32-bit integer, either signed (range −2³¹..2³¹−1) or unsigned (range 0..2³²−1).
• Offset, a 16- or 32-bit displacement referring to a memory location (using any addressing mode).
• Pointer, a 16-bit selector together with a 16- or 32-bit offset.
• Character (8-bit character code).
• String, a sequence of 8-, 16- or 32-bit words (up to 4 Gbyte in length).{{Cite journal|last1=El-ayat|first1=K. A.|last2=Agarwal|first2=R. K.|date=December 1985|title=The Intel 80386 - Architecture And Implementation|journal=IEEE Micro|volume=5|issue=6|pages=4–22|doi=10.1109/mm.1985.304507|s2cid=23062397|issn=0272-1732}}
• BCD, decimal digits (0..9) represented by unpacked bytes.
• Packed BCD, two BCD digits in one byte (range 0..99).

The following i386 assembly source code is for a subroutine named _strtolower that copies a null-terminated ASCIIZ character string from one location to another, converting all alphabetic characters to lower case. The string is copied one byte (8-bit character) at a time.

00000000  55
00000001  89E5
00000003  8B750C
00000006  8B7D08
00000009  FC
0000000A  AC
0000000B  3C41
0000000D  7C06
0000000F  3C5A
00000011  7F02
00000013  0420
00000015  AA
00000016  84C0
00000018  75F0
0000001A  5D
0000001B  C3

The example code uses the EBP (base pointer) register to establish a call frame, an area on the stack that contains all of the parameters and local variables for the execution of the subroutine. This kind of calling convention supports reentrant and recursive code and has been used by Algol-like languages since the late 1950s. A flat memory model is assumed, specifically, that the DS and ES segments address the same region of memory.

The first PC based on the Intel 80386 was the Compaq Deskpro 386. By extending the 16/24-bit IBM PC/AT standard into a natively 32-bit computing environment, Compaq became the first company to design and manufacture such a major technical hardware advance on the PC platform. IBM was offered use of the 80386, but had manufacturing rights for the earlier 80286. IBM therefore chose to rely on that processor for a couple more years. The early success of the Compaq Deskpro 386 played an important role in legitimizing the PC "clone" industry and in de-emphasizing IBM's role within it. The first computer system sold with the 386SX was the Compaq Deskpro 386S, released in July 1988.{{cite journal | last=Satchell | first=Stephen | date=August 1, 1988 | url=https://books.google.com/books?id=dDoEAAAAMBAJ&pg=PA53 | title=Compaq Deskpro 386S: Compaq Introduces First of New Breed to Business Users | journal=InfoWorld | publisher=IDG Publications | volume=10 | issue=31 | pages=54–56 | via=Google Books}}

Prior to the 386, the difficulty of manufacturing microchips and the uncertainty of reliable supply made it desirable that any mass-market semiconductor be multi-sourced, that is, made by two or more manufacturers, the second and subsequent companies manufacturing under license from the originating company. The 386 was for a time (4.7 years) only available from Intel, since Andy Grove, Intel's CEO at the time, made the decision not to encourage other manufacturers to produce the processor as second sources. This decision was ultimately crucial to Intel's success in the market.{{Citation needed|date=July 2008}} The 386 was the first significant microprocessor to be single-sourced. Single-sourcing the 386 allowed Intel greater control over its development and substantially greater profits in later years.

AMD introduced its compatible Am386 processor in March 1991 after overcoming legal obstacles, thus ending Intel's 4.7-year monopoly on 386-compatible processors. From 1991 IBM also manufactured 386 chips under license for use only in IBM PCs and boards.

{{More citations needed section|date=December 2024}}

File:KL IBM 80386DX.jpg

• The AMD Am386SX and Am386DX were almost exact clones of the i386SX and i386DX. Legal disputes caused production delays for several years, but AMD's 40 MHz part eventually became very popular with computer enthusiasts as a low-cost and low-power alternative to the 25 MHz 486SX. The power draw was further reduced in the "notebook models" (Am386 DXL/SXL/DXLV/SXLV), which could operate with 3.3 V and were implemented in fully static CMOS circuitry.
• Chips and Technologies Super386 38600SX and 38600DX were developed using reverse engineering. They sold poorly, due to some technical errors and incompatibilities, as well as their late appearance on the market. They were therefore short-lived products.
• Cyrix Cx486SLC/Cx486DLC could be (simplistically) described as a kind of 386/486 hybrid chip that included a small amount of on-chip cache. It was popular among computer enthusiasts but did poorly with OEMs. The Cyrix Cx486SLC and Cyrix Cx486DLC processors were pin-compatible with i386SX and i386DX respectively. These processors were also manufactured and sold by Texas Instruments.
• IBM 386SLC and 486SLC/DLC were variants of Intel's design which contained a large amount of on-chip cache (8 KB, and later 16 KB). The agreement with Intel limited their use to IBM's own line of computers and upgrade boards only, so they were not available on the open market.
• V.M. Technology VM386SX+ was developed by Tsukuba, Japan-based fabless microprocessor design firm V.M. Technology (VMT), founded by former Intel 4004 and Zilog Z80 microprocessor design engineer Masatoshi Shima, with its primary funding originating from ASCII Corporation. The chip was primarily marketed in East Asia, avoiding the US market deliberately.{{cite magazine|magazine=Microprocessor Report|title=Proliferation of 386/486-Compatible Microprocessors to Accelerate in ’92|date=January 22, 1992|url=

https://websrv.cecs.uci.edu/~papers/mpr/MPR/ARTICLES/060101.PDF}}{{cite magazine|magazine=Microprocessor Report|title=Texas Instruments Extends 486 Line|date=November 15, 1993|url=https://websrv.cecs.uci.edu/~papers/mpr/MPR/ARTICLES/071504.pdf}} Mentions V.M. Technology's history and funding in the article, along with its Intel 386SX pin compatible product, VM386SX+. ALi M6117 SoC contains an x86 core derived from VM386SX+.

Intel originally intended for the 80386 to debut at 16 MHz. However, due to poor yields, it was instead introduced at 12.5 MHz.{{cite magazine

| last = Rosch

| first = Winn L.

| date = 29 September 1987

| title = 386s Weigh In

| url = https://books.google.com/books?id=u5dYmhF7jc4C&pg=PA92

| magazine = PC Mag

| page = 92

| issue = 39

| location =

| publisher = Ziff Davis

| access-date = 8 November 2003

}}

Early in production, Intel discovered a marginal circuit that could cause a system to return incorrect results from 32-bit multiply operations. 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), and affected processors were marked "16 BIT S/W ONLY".{{cite journal |last1=Prosise |first1=Jeff |title=Tutor |journal=PC Magazine |date=February 11, 1992 |volume=11 |issue=3 |page=328}} These latter processors were sold as good parts, since at the time 32-bit capability was not relevant for most users.{{cite magazine

| last = Moran

| first = Tom

| date = 28 September 1987

| title = Intel will not fix gray-market chips with 32-bit multiply bug

| url = https://books.google.com/books?id=ljsEAAAAMBAJ

| magazine = InfoWorld

| volume = 9

| issue = 39

| location =

| publisher = InfoWorld Publishing, Inc.

| access-date = 8 November 2003

}}

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. In this configuration the FPU operated asynchronously to the CPU, usually with a clock rate of 10 MHz. The original Compaq Deskpro 386 is an example of such design. However, this was an annoyance to those who depended on floating-point performance, as the performance advantages of the 80387 over the 80287 were significant. {{citation needed|date=June 2022}}

Image:Intel A80386-12.jpg | A very early 80386 at 12 MHz (A80386-12), before the 32-bit multiply bug was found

Image:Intel A80386-16 16 bit SW Only.jpg | An A80386-16 marked "16 BIT S/W ONLY" with the multiply bug

Image:Intel A80386-16 ΣΣ.jpg | A bug-free A80386-16 marked "ΣΣ"

File:KL Upgrade 386.jpg

Intel later offered a modified version of its 486DX in i386 packaging, branded as the Intel RapidCAD. This provided an upgrade path for users with i386-compatible hardware. The upgrade was a pair of chips that replaced both the i386 and i387. Since the 486DX design contained an FPU, the chip that replaced the i386 contained the floating-point functionality, and the chip that replaced the i387 served very little purpose. However, the latter chip was necessary in order to provide the FERR signal to the mainboard and appear to function as a normal floating-point unit.

Third parties offered a wide range of upgrades, for both SX and DX systems. The most popular ones were based on the Cyrix 486DLC/SLC core, which typically offered a substantial speed improvement due to its more efficient instruction pipeline and internal L1 SRAM cache. The cache was usually 1 KB, or sometimes 8 KB in the TI variant. Some of these upgrade chips (such as the 486DRx2/SRx2) were marketed by Cyrix themselves, but they were more commonly found in kits offered by upgrade specialists such as Kingston, Evergreen Technologies and Improve-It Technologies. Some of the fastest CPU upgrade modules featured the IBM SLC/DLC family (notable for its 16 KB L1 cache), or even the Intel 486 itself. Many 386 upgrade kits were advertised as being simple drop-in replacements, but often required complicated software to control the cache or clock doubling. Part of the problem was that on most 386 motherboards, the A20 line was controlled entirely by the motherboard with the CPU being unaware, which caused problems on CPUs with internal caches.

Overall, it was very difficult to configure upgrades to produce the results advertised on the packaging, and upgrades were often not very stable or not fully compatible.

{{Clear}}

File:Intel i386DX 25.jpg

Original version, released in October 1985. The 16 MHz version was available for 299 USD in quantities of 100.Intel Corporation, "New Product Focus Component: A 32-Bit Microprocessor With A Little Help From Some Friends", Special 32-Bit Issue Solutions, November/December 1985, page 13. The 20 MHz version was available for 599 USD in quantities of 100. The 33 MHz version was made available on April 10, 1989.

• Capable of working with 16- or 32-bit external busses

• Package: PGA-132 which was available in sampling for fourth quarter of 1985Ashborn, Jim; "Advanced Packaging: A Little Goes A Long Way", Intel Corporation, Solutions, January/February 1986, Page 2 or PQFP-132
• Process: First types CHMOS III, 1.5 μm, later CHMOS IV, 1 μm
• Die size: 104 mm² (ca. 10 mm × 10 mm) in CHMOS III and 39 mm² (6 mm × 6.5 mm) in CHMOS IV.
• Transistor count: 275,000
• Specified max clock: 12 MHz (early models), later 16, 20, 25 and 33 MHz

The military version was made using the CHMOS III process technology. It was made to withstand 105 Rads (Si) or greater. It was available for US$945 each in quantities of 100.Intel Corporation, "New Product Focus Components: 32-Bit Military Microprocessor: Up Front And Center", Solutions, January/February 1987, page 15

In 1988, Intel introduced the 80386SX, most often referred to as the 386SX, a cut-down version of the 80386 with a 16-bit data bus, mainly intended for lower-cost PCs aimed at the home, educational, and small-business markets, while the 386DX remained the high-end variant used in workstations, servers, and other demanding tasks. The CPU remained fully 32-bit internally, but the 16-bit bus was intended to simplify circuit-board layout and reduce total cost.{{efn|This was a similar approach to that used by Intel with the 8088, a derivative of the Intel 8086, that was used in the original IBM PC.}} The 16-bit bus simplified designs but hampered performance. Only 24 pins were connected to the address bus, therefore limiting addressing to 16 MB,{{efn|The 16 MB limit was similar to that of the 68000, a comparable processor.}} but this was not a critical constraint at the time. Performance differences were due not only to differing data-bus widths, but also due to performance-enhancing cache memories often employed on boards using the original chip. This version can run 32-bit application software at 70 to 90 percent compared to the regular Intel386 DX CPU.

The original 80386 was subsequently renamed i386DX to avoid confusion. However, Intel subsequently used the "DX" suffix to refer to the floating-point capability of the i486DX. The 387SX was an 80387 part that was compatible with the 386SX (i.e. with a 16-bit databus). The 386SX was packaged in a surface-mount QFP and sometimes offered in a socket to allow for an upgrade.

The 16 MHz 386SX contains the 100-lead BQFP. It was available for USD $165 in quantities of 1000. It has the performance of 2.5 to 3 MIPS as well. The low-power version was available on April 10, 1989. This version that uses 20 to 30 percent less power and has higher operating temperature up to 100 °C than the regular version.

File:Intel386sx a 50 Kc.jpg|80386SX 16 MHz

File:i386SX.jpg|A surface-mount version of Intel 80386SX processor in a Compaq Deskpro computer. It is non-upgradable unless hot-air circuit-board rework is performed

File:Intel 80386 SX die.JPG|Die of Intel 80386SX

The 80386SL was introduced as a power-efficient version for laptop computers. The processor offered several power-management options (e.g. SMM), as well as different "sleep" modes to conserve battery power.Ellis, Simson C., "The 386 SL Microprocessor in Notebook PCs", Intel Corporation, Microcomputer Solutions, March/April 1991, page 20 It also contained support for an external cache of 16 to 64 KB. The extra functions and circuit implementation techniques caused this variant to have over 3 times as many transistors as the i386DX. The i386SL was first available at 20 MHz clock speed,{{cite web|url=http://www.islandnet.com/~kpolsson/micropro/proc1990.htm |title=Chronology of Microprocessors (1990-1992) |publisher=Islandnet.com |access-date=September 17, 2010}} with the 25 MHz model later added.{{cite web|last=Mueller |first=Scott |url=http://www.informit.com/articles/article.aspx?p=130978&seqNum=27 |title=Microprocessor Types and Specifications > P3 (386) Third-Generation Processors |publisher=InformIT |access-date=September 17, 2010}} With this system, it reduced up to 40% foot space than the Intel386 SX system. That translate to lighter and more portable cost-effective system.

Dave Vannier, the chief architect designed this microprocessor. It took them two years to complete this design since it uses the existing 386 architecture to implement. That assist with advanced computer-aided design tools which includes a complete simulation of system board. This die contains the 386 CPU core, AT Bus Controller, Memory Controller, Internal Bus Controller, Cache Control Logic along with Cache Tag SRAM and Clock. This CPU contains 855,000 transistors using one-micron CHMOS IV technology. It was available for USD $176 in 1,000 unit in quantities.Chen, Allan, "The 386 SL Microprocessor Superset: The 32-bit Notebook Hits the Road", Intel Corporation, Microcomputer Solutions, January/February 1991, page 2 The 25-MHz version was available in samples for USD $189 in 1,000-piece quantities, that version was finally made available in production by the end of 1991.Intel Corporation, "New Product Focus: Components: New 25-MHz CPU is Fastest for Notebooks", Microcomputer Solutions, November/December 1991, page 11 It supports up to 32 Megabytes of physical address space.{{cite web | publisher=Intel Corporation | title=Introduction to the Intel386 SL Microprocessor SuperSet Technical Overview | series=Order No. 240852-002 | date=September 1991 | page=37 | url=https://bitsavers.org/components/intel/80386/240852-002_386SL_Technical_Overview_1991.pdf | via=bitsavers.org}} There was a 20-MHz cacheless version of Intel386 SL microprocessor, at the press time samples of this version were available for USD $101 in 1,000-piece quantities.Intel Corporation, "New Product Focus: OEM: Intel386 SL CPU Version Offers Cost-Savings", Microcomputer Solutions, March/April 1992, page 12 There were low-voltage 20-Mhz version and cacheless 16- and 20-Mhz version microprocessors. These low voltage uses 3.3 Volts to supplied them and they do support full static mode as well. They were available for USD $94, $48 and $78 respectively in 1,000 pieces quantities.Chen, Allen, "The New Mobile PC", Intel Corporation, Microcomputer Solutions, July/August 1992, page 3-9

File:80386SL processor from 1990.jpg|i386SL from 1990

In May 1991, Intel introduced an upgrade for IBM PS/2 Model 50 and 60 systems which contain 80286 microprocessors, converting them to full blown 32-bit systems. The SnapIn 386 module is a daughtercard with 20-MHz 386SX and 16-Kbyte direct-mapped cache SRAM memory. It directly plugs into the existing 286 socket with no cables, jumpers or switches. In the winter of 1992, an additional to this module now supported to IBM PS/2 Model 50 Z, 30 286 and 25 286 systems. Both modules were available for USD $495.Intel Corporation, "New Product Focus: Systems: SnapIn 386 Module Upgrades PS/2 PCs", Microcomputer Solutions, September/October 1991, page 12Intel Corporation, "New Product Focus: Systems: More User Can Snap In An Intel386 CPU", Microcomputer Solutions, January/February 1992, page 10

{{Main|RapidCAD}}

A specially packaged Intel 486DX and a dummy floating-point unit (FPU) designed as pin-compatible replacements for an i386 processor and i387 FPU.

{{Main|Intel 80376}}

This was an embedded version of the 80386SX which did not support real mode and paging in the MMU.

{{Main|Intel 80386EX}}

File:KL Intel i386EX.jpg

System and power management and built in peripheral and support functions: Two 82C59A interrupt controllers; Timer, Counter (3 channels); Asynchronous SIO (2 channels); Synchronous SIO (1 channel); Watchdog timer (Hardware/Software); PIO. Usable with 80387SX or i387SL FPUs.

• Data/address bus: 16 / 26 bits
• Package: PQFP-132, SQFP-144 and PGA-168
• Process: CHMOS V, 0.8 μm
• Specified max clock:
• i386EX: 16 MHz @2.7–3.3 volts or 20 MHz @3.0–3.6 volts or 25 MHz @4.5–5.5 volts
• i386EXTB: 20 MHz @2.7–3.6 volts or 25 MHz @3.0–3.6 volts
• i386EXTC: 25 MHz @4.5–5.5 volts or 33 MHz @4.5–5.5 volts

File:KL Intel i386CX.jpg

Transparent power management mode, integrated MMU and TTL compatible inputs (only 386SXSA). Usable with i387SX or i387SL FPUs.

• Data/address bus: 16 / 26 bits (24 bits for i386SXSA)
• Package: BQFP-100
• Voltage: 4.5–5.5 volts (25 and 33 MHz); 4.75–5.25 volts (40 MHz)
• Process: CHMOS V, 0.8 μm
• Specified max clock: 25, 33, 40 MHz

Transparent power management mode and integrated MMU. Usable with i387SX or i387SL FPUs.

• Data/address bus: 16 / 26 bits
• Package: BQFP-100
• Voltage: 3.0 volts (16 MHz) or 3.3 volts (25 MHz)
• Process: CHMOS V, 0.8 μm
• Specified max clock: 16, 25 MHz

File:Intel chips 286 386 486 size comparison.jpg

Windows 95 was the only entry in the Windows 9x series to officially support the 386, requiring at least a 386DX, though a 486 or better was recommended;{{cite web |url=http://support.microsoft.com/kb/138349 |title=Windows 95 Installation Requirements |publisher=Microsoft |date=2000-12-17 |website=Microsoft Support |archive-url=https://web.archive.org/web/20041019021615/http://support.microsoft.com/kb/138349 |archive-date=2004-10-19 |access-date=2020-09-01}} Windows 98 requires a 486DX or higher.{{cite web |url=http://microsoft.com:80/windows98/guide/Win98/SysReq/default.asp |title=Windows 98 Product Guide: System Requirements |publisher=Microsoft |date=1998-12-04 |website=microsoft.com |access-date=2020-08-31 |archive-url=https://web.archive.org/web/19990420193302/http://microsoft.com/windows98/guide/Win98/SysReq/default.asp |archive-date=April 20, 1999 |url-status=live }} In the Windows NT family, Windows NT 3.51 was the last version with 386 support.{{cite web |url=http://support.microsoft.com/kb/139733/ |title=Windows NT 3.5x Setup Troubleshooting Guide |publisher=Microsoft |website=Microsoft Support |access-date=2020-08-31 |archive-url=https://web.archive.org/web/20070223030314/http://support.microsoft.com/kb/139733/ |archive-date=2007-02-23}}{{cite web |url=http://microsoft.com/products/prodref/428_sys.htm |title=Windows NT Workstation 4.0 - Requirements |publisher=Microsoft |date=1999-01-29 |website=microsoft.com |access-date=2020-08-31 |archive-url=https://web.archive.org/web/19990202042900/http://microsoft.com/products/prodref/428_sys.htm |archive-date=1999-02-02}}

Debian GNU/Linux dropped 386 support with the release of 3.1 (Sarge) in 2005 and completely removed support in 2007 with 4.0 (Etch).{{cite web |url=https://www.debian.org/releases/sarge/i386/release-notes/ch-upgrading.en.html |title=Release Notes for Debian GNU/Linux 3.1 ('sarge'), Intel x86 - Upgrades from previous releases |publisher=The Debian Project |date=June 2005 |website=debian.org |access-date=2020-09-01 |archive-date=May 3, 2023 |archive-url=https://web.archive.org/web/20230503163831/https://www.debian.org/releases/sarge/i386/release-notes/ch-upgrading.en.html |url-status=dead }}{{Cite web |date=September 16, 2007 |orig-date= |title=Release Notes for Debian GNU/Linux 4.0 ("etch"), Intel x86 |url=https://www.debian.org/releases/etch/i386/release-notes.en.txt |access-date=November 10, 2023 |website=debian.org |publisher=The Debian Project}} Citing the maintenance burden around SMP primitives, the Linux kernel developers cut support from the development codebase in December 2012, later released as kernel version 3.8.

Among the BSDs, FreeBSD's 5.x releases were the last to support the 386; support for the 386SX was cut with release 5.2,{{cite web |url=https://www.freebsd.org/releases/5.2R/hardware-i386.html |title=FreeBSD/i386 5.2-RELEASE Hardware Notes |publisher=The FreeBSD Project |date=January 2004 |website=freebsd.org |access-date=2020-08-31}} while the remaining 386 support was removed with the 6.0 release in 2005.{{cite web |url=https://www.freebsd.org/releases/6.0R/relnotes-i386.html |title=FreeBSD/i386 6.0-RELEASE Release Notes |publisher=The FreeBSD Project |date=November 2005 |website=freebsd.org |access-date=2020-08-31}} OpenBSD removed 386 support with version 4.2 (2007),{{cite web |url=https://www.openbsd.org/plus42.html |title=OpenBSD 4.2 Changelog |publisher=The OpenBSD project |date=November 2007 |website=openbsd.org |access-date=2020-08-31}} DragonFly BSD with release 1.12 (2008),{{cite web |url=https://www.dragonflybsd.org/release112/ |title=DragonFly 1.12.0 Release Notes |publisher=The DragonFly Project |date=2008-02-26 |website=dragonflybsd.org |access-date=2020-08-31}} and NetBSD with the 5.0 release (2009).{{cite web |url=https://www.netbsd.org/releases/formal-5/NetBSD-5.0.html |title=Announcing NetBSD 5.0 |publisher=The NetBSD Foundation |date=April 2009 |website=netbsd.org |access-date=2020-08-31}}

• List of Intel microprocessors

{{notelist}}

{{Reflist|refs=

A. K. Ray, K. M. Bhurchandi, "Advanced microprocessors and peripherals".

|2}}

• Intel Corporation
• {{cite book |author=Intel Corporation |author-mask=1 |date=1987 |title=Intel 80386 Programmer's Reference Manual 1986 |url=http://css.csail.mit.edu/6.858/2013/readings/i386.pdf}}
• {{cite book |author=Intel Corporation |author-mask=1 |url=https://archive.org/details/bitsavers_intel80386ontothe80386Apr86_12904120 |title=Introduction to the 80386, Including the 80386 Data Sheet |date=April 1986 |id=231630-002}}
• {{cite book |author=Intel Corporation |author-mask=1 |url=https://archive.org/details/bitsavers_inteldataBrocessorsandPeripheralHandbookVolume1_79473179 |series=Microprocessors and Peripheral Handbook |volume=1 |title=Microprocessor |date=October 1987 |id=231630-004 |isbn=1-55512-073-3 |chapter=4. 80386 Microprocessor Family}}
• {{cite book |author=Intel Corporation |author-mask=1 |url=https://archive.org/details/bitsavers_inteldataBrocessorandPeripheralHandbookVol1_114989017 |series=Intel Microprocessor and Peripheral Handbook |volume=1 |title=Microprocessor |chapter=4. INTEL386™ Family |date=November 1988 |id=231630-005 |isbn=1-55512-041-5}}
• [http://www.cpu-world.com/CPUs/80386/ Intel 80386 processor family]
• [http://www.pcjs.org/blog/2015/02/23/ Detailed list of early 80386 steppings (revisions)]
• {{cite web |first=Ken |last=Shirriff |title=Examining the silicon dies of the Intel 386 processor |date=October 2023 |url=http://www.righto.com/2023/10/intel-386-die-versions.html}}
• {{cite web |author-mask=1 |first=Ken |last=Shirriff |title=Reverse engineering the Intel 386 processor's register cell |date=November 2023 |url=http://www.righto.com/2023/11/reverse-engineering-intel-386.html }}
• {{cite web |author-mask=1 |first=Ken |last=Shirriff |title=Inside the Intel 386 processor die: the clock circuit |date=December 2023 |url=http://www.righto.com/2023/11/intel-386-clock-circuit.html}}
• {{cite web |author-mask=1 |first=Ken |last=Shirriff |title=Reverse engineering the barrel shifter circuit on the Intel 386 processor die |date=December 2023 |url=http://www.righto.com/2023/12/386-barrel-shifter.html}}

{{Intel processors|discontinued}}

{{Authority control}}

80386

Category:32-bit microprocessors

Category:Computer-related introductions in 1985

Category:X86 microarchitectures