Editing I386 (section)

===Early 5 V models===

==== i386DX ====
[[File:Intel i386DX 25.jpg|thumb|Intel i386DX, 25&nbsp;MHz]]
Original version, released in October 1985. The 16&nbsp;MHz version was available for 299&nbsp;[[United States dollar|USD]] in quantities of 100.<ref>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.</ref> The 20&nbsp;MHz version was available for 599 USD in quantities of 100.<ref name="auto"/> The 33&nbsp;MHz version was made available on April 10, 1989.<ref name="Lewnes, Ann 1989, page 2"/>
* Capable of working with 16- or 32-bit external busses
<!--* Cache: depends on mainboard-->
* Package: [[Pin Grid Array|PGA]]-132 which was available in sampling for fourth quarter of 1985<ref>Ashborn, Jim; "Advanced Packaging: A Little Goes A Long Way", Intel Corporation, Solutions, January/February 1986, Page 2</ref> or PQFP-132
* Process: First types [[CHMOS]] III, 1.5&nbsp;μm, later CHMOS IV, 1&nbsp;μm
* Die size: 104&nbsp;mm² (ca. 10&nbsp;mm × 10&nbsp;mm) in CHMOS III and 39&nbsp;mm² (6&nbsp;mm × 6.5&nbsp;mm) in CHMOS IV.
* Transistor count: 275,000<ref name=intelquickref/><ref name="Lewnes, Ann 1989, page 2"/>
* Specified max clock: 12&nbsp;MHz (early models), later 16, 20, 25 and 33&nbsp;MHz

==== M80386 ====
The military version was made using the CHMOS III process technology. It was made to withstand 105 [[Rad (unit)|Rads]] (Si) or greater. It was available for US$945 each in quantities of 100.<ref>Intel Corporation, "New Product Focus Components: 32-Bit Military Microprocessor: Up Front And Center", Solutions, January/February 1987, page 15</ref>

===={{anchor|The 80386SX variant}}  80386SX====
<!-- [[File:Intel386sx a 50 Kc.jpg|right|thumb|80386SX 16 MHz]]
[[File:i386SX.jpg|200px|right|thumb|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|200px|right|thumb|[[Die (integrated circuit)|Die]] of Intel 80386SX]]
[[File:80386SL processor from 1990.jpg|200px|right|thumb|i386SL from 1990]] -->

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 [[Intel 8088|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&nbsp;[[Megabyte|MB]],{{efn|The 16 MB limit was similar to that of the [[Motorola 68000|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 memory|cache memories]] often employed on boards using the original chip. This version can run 32-bit application software at 70 to 90 percent the speed of the regular Intel386 DX CPU.<ref name="Intel Corporation 1992, page 11"/>

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 [[Quad flat package|QFP]] and sometimes offered in a socket to allow for an upgrade.

The 16&nbsp;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.<ref name="Lewnes, Ann 1988, page 2"/> 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&nbsp;°C than the regular version.<ref name="Lewnes, Ann 1989, page 2"/>

<gallery>
File:Intel386sx a 50 Kc.jpg|80386SX 16&nbsp;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 (integrated circuit)|Die]] of Intel 80386SX
</gallery>

====80386SL{{anchor|The i386SL variant}}====
The '''80386SL''' was introduced as a power-efficient version for [[laptop computer]]s. The processor offered several power-management options (e.g. [[System Management Mode|SMM]]), as well as different "sleep" modes to conserve [[battery (electricity)|battery]] power.<ref>Ellis, Simson C., "The 386 SL Microprocessor in Notebook PCs", Intel Corporation, Microcomputer Solutions, March/April 1991, page 20</ref> It also contained support for an external [[CPU cache|cache]] of 16 to 64 [[Kilobyte|KB]]. The extra functions and circuit implementation techniques caused this variant to have over 3 times as many [[transistor]]s as the i386DX. The i386SL was first available at 20&nbsp;MHz clock speed,<ref>{{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}}</ref> with the 25&nbsp;MHz model later added.<ref>{{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}}</ref> 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.<ref name="Intel Corporation 1992, page 11"/>

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.<ref name="Chen, Allan 1991, page 2">Chen, Allan, "The 386 SL Microprocessor Superset: The 32-bit Notebook Hits the Road", Intel Corporation, Microcomputer Solutions, January/February 1991, page 2</ref> 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.<ref>Intel Corporation, "New Product Focus: Components: New 25-MHz CPU is Fastest for Notebooks", Microcomputer Solutions, November/December 1991, page 11</ref> It supports up to 32 Megabytes of physical address space.<ref name="Intel Corporation 1992, page 11"/><ref>{{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}}</ref>  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.<ref>Intel Corporation, "New Product Focus: OEM: Intel386 SL CPU Version Offers Cost-Savings", Microcomputer Solutions, March/April 1992, page 12</ref>  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.<ref>Chen, Allen, "The New Mobile PC", Intel Corporation, Microcomputer Solutions, July/August 1992, page 3-9</ref>

<gallery>
File:80386SL processor from 1990.jpg|i386SL from 1990
</gallery>

==== SnapIn 386 ====
In May 1991, Intel introduced an upgrade for [[IBM PS/2 Model 50]] and [[IBM PS/2 Model 60|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]], [[IBM PS/2 Model 30 286|30 286]] and [[IBM PS/2 Model 25 286|25 286]] systems. Both modules were available for USD $495.<ref>Intel Corporation, "New Product Focus: Systems: SnapIn 386 Module Upgrades PS/2 PCs", Microcomputer Solutions, September/October 1991, page 12</ref><ref>Intel Corporation, "New Product Focus: Systems: More User Can Snap In An Intel386 CPU", Microcomputer Solutions, January/February 1992, page 10</ref>

==== RapidCAD ====
{{Main|RapidCAD}}
A specially packaged [[Intel 486]]DX and a dummy [[floating-point unit]] (FPU) designed as pin-compatible replacements for an i386 processor and [[i387]] FPU.