Editing amd/am486

{{amd title|Am486}}
{{ic family
| title             = AMD Am486
| image             = AMD Am486.jpg
| caption           = Enhanced {{\|Am486DX2-66SV8B}}
| developer         = AMD
| manufacturer      = AMD
| type              = Microprocessors
| first announced   = February, 1992
| first launched    = April 1993
| production start  = 1992
| production end    = 
| arch              = 80486
| isa               = IA-32
| microarch         = 
| word              = 32 bit
| proc              = 700 nm
| proc 2            = 500 nm
| proc 3            = 350 nm
| tech              = CMOS
| clock min         = 33 Mhz
| clock max         = 120 MHz
| package           = CPGA-168
| package 2         = SQFP-208
| socket            = Socket 1
| socket 2          = Socket 2
| socket 3          = Socket 3

| succession       = Yes
| predecessor      = Am386
| predecessor link = amd/am386
| successor        = Am5x86
| successor link   = amd/am5x86
}}
'''Am486''' was a family of {{arch|32}} 4th-generation [[x86]] microprocessors introduced by [[AMD]] in [[1993]]. Am486 chips were compatible with [[Intel]]'s {{intel|80486}} and offered equivalent performance for cheaper prices.

== History ==
Just like AMD's {{amd|Am386}}, Am486 was also delayed after expensive and lengthy litigation with Intel. The first models of the Am486 (Am486DX) were finally introduced in April of 1993. The first set of AMD chips were based on Intel's microcode cleanroom implementation. AMD manufactured their first Am486s at their Submicron Development Center (SDC) in [[Wikipedia:Sunnyvale, CA|Sunnyvale, CA]] on a [[0.7 µm process]]. Chips were originally restricted to AMD's own foundry as they did not believe their agreement with Intel allowed them use outside foundry (this became irrelevant later on)<ref>{{cite book|year=1993|title=DataQuest Monday|publisher=DataQuest|pages=15-16}}</ref>. By the end of 1993 AMD revenue of the Am486 reached $250M taking a total of 20% share of the market<ref name="book1">{{cite book|last=Fletcher|first=Andrew|middle=E|year=2013|title=Profile of the Worldwide Semiconductor Industry - Market Prospects to 1997: Market Prospects to 1997|publisher=Elsevier|pages=96-97|isbn=9781483284859}}</ref>. By 1995 that share peaked at 40%.

AMD's last models (Am486DX4's) for this family were clocked at up to 120 MHz which gave AMD a significant performance advantage compared to Intel's earliest {{intel|Pentium}} chips (which were only clocked at around 60 MHz). The Am486DX4 lower price (compared to Intel's DX4) and socket-comparability ensured strong sale for quite some time after their introduction.

Earliest ([[700 nm]]) models operated at 5V, when AMD undergone a [[process shrink]] around late 1994/95 they introduced 3.3V models. Initially all models packed 8KB L1$ that used write-through policy. AMD later (See [[#Larger Cache & Post-lawsuit|§ Larger Cache]]) introduced various models with other cache set ups including write-back and double the L1$ size which was manufactured on a [[350 nm process]].

== Die ==

=== {{\|Am486DX2-66}} ===
[[File:AMD 80486DX2 die.jpg|700px]]

=== {{\|Am486DX4-100NV8T}} ===
[[File:AMD 80486DX4-100 die.JPG|700px]]

== Members ==

=== Am486DX ===
[[File:AMD Am486DX2 66MHz 2007 03 27.jpg|thumb|200px|right|{{\|Am486DX2-66}} from 1994.]]
The Am486DX chips are the standard 486 chips with an integrated FPU on-die. First versions introduced had lower clock frequency which matched their external bus speed. Later versions introduced a [[clock multiplier]]: DX2 having a multiplier of 2 and DX4 a multiplier of 3.
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<table class="wikitable sortable">
<tr><th colspan="7" style="background:#D6D6FF;">Am486DX Processors</th></tr>
<tr><th>Model</th><th>Launched</th><th>Process</th><th>Freq</th><th>Bus</th><th>Max Mem</th><th>Package</th></tr>
{{#ask: [[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[core name::~486DX*]]
 |?full page name
 |?model number
 |?first launched
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 |?bus speed#MHz
 |?max memory#GB
 |?package
 |format=template
 |template=proc table 2
 |userparam=8
 |sep=,
 |mainlabel=-
}}
{{table count|col=16|ask=[[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[core name::~486DX*]]}}
</table>

=== Am486SX ===
The Am486SX chips are somewhat a crippled version of the 486DX, models that do not include an integrated FPU. Those chips were sold at cheaper prices because of the smaller die (in the case of omitted FPU on-die) or because the FPU was defective and was thus disabled and sold as SX. Nevertheless they became an attractive option for those looking for just a performance upgrade from their older {{amd|Am386|386}}.
<!-- NOTE: 
           This table is generated automatically from the data in the actual articles.
           If a microprocessor is missing from the list, an appropriate article for it needs to be
           created and tagged accordingly.

           Missing a chip? please dump its name here: http://en.wikichip.org/wiki/WikiChip:wanted_chips
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<table class="wikitable sortable">
<tr><th colspan="7" style="background:#D6D6FF;">Am486SX Processors</th></tr>
<tr><th>Model</th><th>Launched</th><th>Process</th><th>Freq</th><th>Bus</th><th>Max Mem</th><th>Package</th></tr>
{{#ask: [[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[core name::~486SX*]]
 |?full page name
 |?model number
 |?first launched
 |?process
 |?base frequency#MHz
 |?bus speed#MHz
 |?max memory#GB
 |?package
 |format=template
 |template=proc table 2
 |userparam=8
 |mainlabel=-
}}
{{table count|col=7|ask=[[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[core name::~486SX*]]}}
</table>

=== Am486 Embedded ===
AMD sold a number of processors geared specifically toward the embedded market. Unlike the {{amd|Am386}} embedded chips, the Am486 versions were identical to their non-embedded SX/DX counterparts. They were only different from AMD's own company-support standpoint. Embedded chips were marked with "'''E'''" suffix (e.g. "SE"/"DE").
<!-- NOTE: 
           This table is generated automatically from the data in the actual articles.
           If a microprocessor is missing from the list, an appropriate article for it needs to be
           created and tagged accordingly.

           Missing a chip? please dump its name here: http://en.wikichip.org/wiki/WikiChip:wanted_chips
-->
<table class="wikitable sortable">
<tr><th colspan="7" style="background:#D6D6FF;">Am486 Embedded Processors</th></tr>
<tr><th>Model</th><th>Launched</th><th>Process</th><th>Freq</th><th>Bus</th><th>Max Mem</th><th>Package</th></tr>
{{#ask: [[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[market segment::Embedded]]
 |?full page name
 |?model number
 |?first launched
 |?process
 |?base frequency#MHz
 |?bus speed#MHz
 |?max memory#GB
 |?package
 |format=template
 |template=proc table 2
 |userparam=8
 |mainlabel=-
}}
{{table count|col=7|ask=[[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[market segment::Embedded]]}}
</table>

=== Larger Cache & Post-lawsuit ===
[[File:AMD 486 DX2 66 NV8T Front.jpg|250px|thumb|right|{{\|Am486DX2-66NV8T}} "No ICE" chip.]]
In 1994 AMD introduced a number of newer models which had Write-Back cache policy as well as a few models with twice as large cache (16 KB vs 8 KB). The older models were renamed with a "'''V8T'''" suffix; V = 3.3V, 8 = 8 KB cache, T = Write-Through Policy (e.g. {{\|Am486DX2-80V8T}}). The new models with the Write-Back Policy had "'''B'''" instead of "T" and the 16 KB versions had "'''16'''" instead of "8" (e.g. {{\|Am486DX2-66V16B}}).

Following the conclusion of an 8-year legal battle with [[Intel]], the results was [[AMD]] was allowed to copy and distribute {{amd|Am286}}s and {{amd|Am386}}s chips. Unfortunately it was also concluded that AMD did not have the copyright for Intel's {{intel|80486}} microcode. AMD was forced to destroy the older models containing Intel's [[in-circuit emulation]] (ICE) [[microcode]]. The "ICE microcode" was referred to the [[control program]] which was stored in the {{intel|80386|386's}}/{{intel|84386|486's}} programmable logic array in the processor. All newer AMD models were marked with an "'''N'''" (for "No ICE"). For example the previous model {{\|Am486DX4-100V8T}} became {{\|Am486DX4-100NV8T}}.

<!-- NOTE: 
           This table is generated automatically from the data in the actual articles.
           If a microprocessor is missing from the list, an appropriate article for it needs to be
           created and tagged accordingly.

           Missing a chip? please dump its name here: http://en.wikichip.org/wiki/WikiChip:wanted_chips
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<table class="wikitable sortable">
<tr><th colspan="7" style="background:#D6D6FF;">Newer Processors</th></tr>
<tr><th>Model</th><th>Launched</th><th>Process</th><th>Freq</th><th>Bus</th><th>Max Mem</th></tr>
{{#ask: [[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[model number::~*-??*V*]]
 |?full page name
 |?model number
 |?first launched
 |?process
 |?base frequency#MHz
 |?bus speed#MHz
 |?max memory#GB
 |format=template
 |template=proc table 2
 |userparam=7
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{{table count|col=16|ask=[[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[model number::~*-??*V*]]}}
</table>

=== Enhanced Am486 ===
{{see also|amd/am5x86|l1=Am5x86}}
[[File:AMD Am486DX4-120.jpg|200px|right|thumb|{{\|Am486DX4-120SV8B}} Enhanced Am486 @ 120 MHz.]]
In 1996 AMD introduced a number of chips they branded as "Enhanced Am486". Those processors had a number of new power saving features (e.g. SMM and Stop Clock Mode). The additional features found on the enhanced Am486 get disabled if the processor is used in a socket that does not support them, making them backwards-compatible. The new Enhanced Am486s were marked with "'''S'''" (for SMM), for example {{\|Am486DX2-66SV8B}}. Note that some later models did not include the "S" even though they were enhanced models.

<!-- NOTE: 
           This table is generated automatically from the data in the actual articles.
           If a microprocessor is missing from the list, an appropriate article for it needs to be
           created and tagged accordingly.

           Missing a chip? please dump its name here: http://en.wikichip.org/wiki/WikiChip:wanted_chips
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<table class="wikitable sortable">
<tr><th colspan="7" style="background:#D6D6FF;">Enhanced Processors</th></tr>
<tr><th>Model</th><th>Launched</th><th>Process</th><th>Freq</th><th>Bus</th><th>Max Mem</th><th>Package</th></tr>
{{#ask: [[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[has feature::System Management Mode]]
 |?full page name
 |?model number
 |?first launched
 |?process
 |?base frequency#MHz
 |?bus speed#MHz
 |?max memory#GB
 |?package
 |format=template
 |template=proc table 2
 |userparam=8
 |mainlabel=-
}}
{{table count|col=16|ask=[[Category:microprocessor models by amd]][[instance of::microprocessor]][[microprocessor family::Am486]][[has feature::System Management Mode]]}}
</table>

== Documents ==

=== Datasheets ===
* [[:File:Am486DX (May, 1993).pdf|Am486DX (May, 1993)]], Publication #17852, For -40/-33
* [[:File:AMD Am486DX4 NV8T (July, 1995).pdf|AMD Am486DX4 NV8T (July, 1995)]], Publication #19160, For 100/120
* [[:File:AMD Am486DX2 NV8T (August, 1995).pdf|AMD Am486DX2 NV8T (August, 1995)]], Publication #19200, For: 66/80
* [[:File:AMD Enhanced Am486 (March, 1996).pdf|AMD Enhanced Am486 (March, 1996)]], Publication #19225, For: DX4 -75/-100/-120 / DX2 -66/-80
* [[:File:AMD Enhanced Am486 (March, 1997).pdf|AMD Enhanced Am486 (March, 1997)]], Publication #20736, For: DX4 -100 / DX2 -66
* [[:File:Am486DE (April, 1996).pdf|Am486DE (April, 1996)]], Publication #20037, For: 66

=== Manuals ===
* [[:File:Am486 DX-DX2 Microprocessor Hardware Reference Manual (1993).pdf|Am486 DX/DX2 Microprocessor Hardware Reference Manual (1993)]]
* [[:File:Am486 Microprocessor Software User's Manual (1994).pdf|Am486 Microprocessor Software User's Manual (1994)]]

=== Thermal & Clock ===
* [[:File:Clock Gating Recommendations (Am486, Am5x86, K5) (August 1995).pdf|Clock Gating Recommendations]]; Publication #19195 Revision C/0; August 1995
* [[:File:CPU Thermal Management (Am486, Am5x86, K5) (August 1995).pdf|CPU Thermal Management]]; Publication #18448 Revision D/0; August 1995.
* [[:File:Low Voltage Power Supply Circuits (Am486, Am5x86, K5) (August 1995).pdf|Low Voltage Power Supply Circuits]]; Publication #19197 Revision D/0; August 1995.
* [[:File:Phase Lock Loop (PLL) Clock Control (Am486, Am5x86, K5) (August 1995).pdf|Phase Lock Loop (PLL) Clock Control]]; Publication #18495 Revision D/0; August 1995.

=== Others ===
* [[:File:Am486 Microprocessor PCI Customer Development Platform (December 18, 1998).pdf|Am486 Microprocessor PCI Customer Development Platform (December 18, 1998)]]

== References ==
{{reflist}}
designer	AMD +
first announced	February 1992 +
first launched	April 1993 +
full page name	amd/am486 +
instance of	microprocessor family +
instruction set architecture	IA-32 +
main designer	AMD +
manufacturer	AMD +
name	AMD Am486 +
package	CPGA-168 + and SQFP-208 +
process	700 nm (0.7 μm, 7.0e-4 mm) +, 500 nm (0.5 μm, 5.0e-4 mm) + and 350 nm (0.35 μm, 3.5e-4 mm) +
socket	Socket 1 +, Socket 2 + and Socket 3 +
technology	CMOS +
word size	32 bit (4 octets, 8 nibbles) +