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| successor link = amd/am5x86 | | successor link = amd/am5x86 | ||
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| − | '''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}} | + | '''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}}, but offered very equivalent performance for cheaper prices. |
== History == | == 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 | + | 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 it 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. | 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. | ||
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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}}). | 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 | + | 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 right copy Intel's microcode for the {{intel|80486}}. 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}}. |
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=== Enhanced Am486 === | === Enhanced Am486 === | ||
| − | + | 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. | |
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| − | 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. | ||
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* [[:File:Am486 DX-DX2 Microprocessor Hardware Reference Manual (1993).pdf|Am486 DX/DX2 Microprocessor Hardware Reference Manual (1993)]] | * [[: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)]] | * [[:File:Am486 Microprocessor Software User's Manual (1994).pdf|Am486 Microprocessor Software User's Manual (1994)]] | ||
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=== Others === | === Others === | ||
Facts about "Am486 - AMD"
| 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) + |