AMD Am5x86

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Kl AMD Am5x86-P75 PQFP.jpg
Embedded version of the AMD 5x86-P75
Production: 1995 to 1999
Producer: AMD
Processor clock: 133 MHz to 150 MHz
FSB cycle: 33 MHz to 50 MHz
L1 cache size: 16 kB
Instruction set : x86
Base: Socket 1, 2, 3
The one am5x86-P75

The AMD Am5x86 or Am486DX5 is a microprocessor from Advanced Micro Devices . It is also referred to as X5 internally by AMD , probably due to the higher multiplier compared to the DX4 models.


The Am5x86 was introduced in November 1995. It is largely based on the Enhanced Am486DX4 , but it was manufactured in a smaller process and got an L1 cache that is twice as large with 16 kB. The clock frequency and the multiplier could be increased further. In contrast to its namesake Cyrix 5x86 , the Am5x86 has no further modifications or features of the 5th generation.


Because of its internal multiplier of "4", the Am5x86 is actually the only real 80486DX4 (these only have an internal multiplier of "3"), but because of its high speed compared to the other 80486 CPUs and the strong competition from Intel's Pentium Equipped with a new name and a model rating called P-Rating : The Am5x86-P75 clocks at 133 MHz (33 MHz × 4). Variants with 150 MHz (50 MHz × 3, Am5x86-P75 +) and 160 MHz (40 MHz × 4, Am5x86-P90) have been announced. The 150 MHz version is extremely rare, but the 160 MHz version never appeared. Models below 133 MHz were sold as Enhanced Am486 with 16 kB L1 cache.

Along with the Cyrix 5x86 and the NexGen Nx586 , it is the first processor to use a P rating .


For the Am5x86-P75 special mainboards came on the market, on which a multiplier of "4 ×" can be set. If this option is not available, the CPU can be operated with a multiplier of "3 ×" and is then recognized as Am486DX4. When operating at 100 MHz (33 MHz × 3), if a very large heat sink is used, operation without a processor fan is possible. Operation at 120 MHz (40 MHz × 3) is also possible with a processor fan.

In contrast to the Cyrix 5x86 100 / 120GP, the Am5x86-P75 interprets a multiplier setting of 2 × as 4 ×, which means that the Am5x86-P75 can theoretically run fully on any 486 mainboard with a standard 3 socket, which has a processor supply voltage of 3, 45 or 3.3 volts supported. If there is only a 5-volt CPU supply voltage, you can use a standard voltage converter intermediate socket from 5 V to 3.3 / 3.45 V for this purpose, with a multiplier of 2 × on the intermediate socket for the Am5x86-P75 set so that the processor runs at 133 MHz (33 MHz × 4).

The Am5x86-P75 is available in three versions, which differ in terms of their maximum permissible processor housing surface temperature:

  • AMD-X5-133 ADW  = +55 ° C
  • AMD-X5-133 ADY  = +75 ° C
  • AMD-X5-133 ADZ  = +85 ° C

Although the Am5x86-P90 160 MHz never came onto the market, systems with an Am5x86 running at 160 MHz were still unofficially in circulation at the time. This is an overclocked Am5x86-P75 133 MHz (mostly the ADZ version), which is operated with 40 MHz FSB instead of 33 MHz and is equipped with a correspondingly powerful cooling system.


The Am5x86 was manufactured for ordinary PCs until 1999, but is still manufactured for use in embedded systems .

Model data

Am5x86 (X5)

Alternative designation: Am486DX5

Am5x86-P75 with the second designation AMD-X5.
AMD Am5x86 with the alternative name Am486DX5.
  • L1 cache: 16 kB (unified)
  • L2 cache: depending on the mainboard or chipset used
  • Socket 3 with an FSB of 33, 40 or 50 MHz
  • Operating voltage (VCore): 3.45 and 3.3 V.
  • Release DATE: September 1995
  • Manufacturing technology: 0.35 µm
  • The size: 43 mm² with 1.6 million transistors
  • Clock rates: 133 MHz
    • Am5x86-P75: 133 MHz (33 MHz × 4)
    • Am5x86-P75 +: 150 MHz (50 MHz × 3) - very rare
    • Am5x86-P90: 160 MHz (40 MHz × 4) - not released

See also

Web links

Data Sheets