AMD 5x86

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AMD 5x86

The Am5x86 processor is an x86-compatible CPU

Central processing unit

A central processing unit is an electronic circuit that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term "CPU" ever came into widespread usage....
introduced in 1995 by AMD for use in 486-class computer

Computer

A computer is a machine that manipulates Data according to a list of Code .The first devices that resemble modern computers date to the mid-20th century , although the computer concept and various machines similar to computers existed earlier....
systems. It was one of the fastest, and most universally-compatible upgrade paths for users of 486 systems.

Introduced in November 1995, the Am5x86 (also known as 5x86-133, Am5x86, X5-133, and sold under various 3rd-party labels such as "Turbochip") is an Enhanced Am486

Am486

The Am486 is a 80486-class family of computer central processing unit that was produced by AMD in the 1990s. Intel beat AMD to market by nearly four years, but AMD priced its 40 MHz 486 at or below Intel's price for a 33 MHz chip, offering about 20% better performance for the same price....
processor with an internally-set multiplier

Clock signal

In electronics and especially Synchronous logic digital circuits, a clock signal is a Signalling used to coordinate the actions of two or more Electronic circuit....
of 4, allowing it to run at 133 MHz on systems without official support for clock-multiplied DX2

Intel 80486DX2

The Intel's i486DX2 is a central processing unit produced by Intel that was introduced in 1992. The i486DX2 was nearly identical to the Intel 80486DX but for the addition of clock multiplier circuitry....
or DX4 486

Intel 80486DX4

The Intel IntelDX4 is a clock-tripled 80486 microprocessor with 16kb L1 cache. Intel named it deceptively during litigation with AMD over trademarks....
processors.

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Encyclopedia

The Am5x86 processor is an x86-compatible CPU

Central processing unit

Computer

Am486

Clock signal

Intel 80486DX2

Intel 80486DX4

The Intel IntelDX4 is a clock-tripled 80486 microprocessor with 16kb L1 cache. Intel named it deceptively during litigation with AMD over trademarks....
processors. Like all Enhanced Am486, the Am5x86 featured write-back L1 cache

CPU cache

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access computer storage. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations....
, and unlike all but a few, a generous 16 kibibyte

Kibibyte

A kibibyte is a unit of information or computer storage, established by the International Electrotechnical Commission in 2000. Its symbol is KiB....
s rather than the more common 8 KiB. A rare 150 MHz-rated part may have also been released by AMD.

Since having a clock multiplier of four was not part of the original Socket 3 design, AMD made the 5x86 accept a 2x setting from the motherboard and instead operate at a rate of 4x. When using an Am5x86, the motherboard must be set to the 2x setting. The chip will actually physically fit into an older 486 socket such as a socket 1 or 2 or the original 168-pin 80486 socket, but doing this requires a replacement voltage regulator, since the AMD chip runs at 3.45 volts.

The combination of clock speed and the relatively large 16 KiB write-back L1 cache allowed the 5x86 to equal or slightly exceed an Intel Pentium

Pentium

Introduced on March 22, 1993, the original Pentium was the first superscalar x86 architecture microprocessor. Its fifth-generation x86 microarchitecture was a direct extension of the 80486 architecture with dual integer pipeline s, a faster FPU unit, wider data bus, and features for further reduced address calculation latency....
75 MHz processor in integer

Integer

The integers are natural numbers including 0 and their negative and non-negative numberss . They are numbers that can be written without a fractional or decimal component, and fall within the set ....
arithmetic performance. Also, because it was based on a pure 486 design, it was compatible with older systems, something its slightly faster rival, the Cyrix Cx5x86

Cyrix Cx5x86

Released in August 1995, four months before the more famous Cyrix 6x86, the Cyrix 5x86 was one of the fastest Central processing units ever produced for Socket 3 computer systems....
, had trouble with. The CPU was commonly overclocked to 160 MHz, thereby giving performance similar to that of a Pentium 90 MHz system. Although it has been reported that individuals have successfully run the chip at 200 MHz, this would seldom have been achievable due to the rarity of VLB

VESA Local Bus

The VESA Local Bus was mostly used in personal computers. VESA Local Bus worked alongside the Industry Standard Architecture bus; it acted as a high-speed conduit for memory-mapped I/O and Direct memory access, while the ISA bus handled interrupts and port-mapped I/O....
video card

Video card

A video card, also known as a graphics accelerator card, display adapter, or graphics card, is an expansion card whose function is to generate and output images to a display....
s and motherboard

Motherboard

A motherboard is the central printed circuit board in some complex electronic systems, such as modern personal computers. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple Inc....
s (especially the cache RAM

Static random access memory

Static random access memory is a type of semiconductor memory where the word static indicates that, unlike dynamic random access memory, it does not need to be periodically memory refresh, as SRAM uses bistable latch to store each bit....
) that could cope with a 50 MHz system bus

Front side bus

In personal computers, the Front Side Bus is the bus that carries data between the central processing unit and the Northbridge .Depending on the processor used, some computers may also have a back side bus that connects the CPU to the CPU cache....
. The image of the Socket 3 version above, of type ADZ, was in fact the preferred version of the chip because it was rated for higher temperatures and thus more forgiving of overclocking.

The Am5x86 is also notable for the first-ever use of the controversial PR rating

PR rating

The PR system was developed by AMD in the mid-1990s as a method of comparing their x86 processors to those of rival Intel....
. Because the 5x86 was the equal of a Pentium 75 MHz processor in benchmarks, AMD later marketed the chip as "Am5x86-P75".

Sales of the Am5x86 were an important source of revenue for AMD at a time when lengthy delays in bringing the AMD K5

AMD K5

The K5 was Advanced Micro Devices first X86 architecture processor to be developed entirely in-house. Introduced in March 1996, its primary competition was Intel Corporation Pentium microprocessor....
to production were threatening the company's profitability.

AMD manufactured the Am5x86 processor for ordinary PC systems until 1999. It was popular for entry-level desktop systems, appeared in many different notebook models, and also sold separately as an upgrade processor for older 486 systems. Several companies made upgrade kits which packaged an AMD 5x86 with a voltage regulator and socket converter, which allowed its use on almost any 486 motherboard ever produced. The chips were even used on later Acorn

Acorn

The acorn, or oak nut, is the nut of the oak tree . It is a nut , containing a single seed , enclosed in a tough, leathery shell, and borne in a cup-shaped cupule....
RiscPC "PC card" second processors. The RiscPC's OpenBus only supported a 32-bit memory interface, which meant that the Pentium

Pentium

Pentium OverDrive

The Pentium OverDrive was a microprocessor marketing brand name used by Intel, to cover a variety of consumer upgrade products sold in the mid 1990s....
for 486 systems was a troublesome CPU, with many compatibility issues, and so was not used. The 5x86 therefore provided the acme of RiscPC Windows performance.

The chip remains in production today, and is a popular choice for use in embedded controllers. One derivative of the 5x86 family is the core used in the Élan SC520 family of microcontrollers marketed by AMD.

Models

Am5x86-P75 (X5-133)

350 nm CMOS
CMOS

Complementary metal?oxide?semiconductor , is a major class of integrated circuits. CMOS technology is used in microprocessors, microcontrollers, Static Random Access Memory, and other digital logic circuits....
process
L1 Cache
CPU cache

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access computer storage. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations....
: 16 KiB unified. write-back or write-through. 4-way associative
Socket 3
Socket 3

Socket 3 was a type of CPU_Sockets into which various x86 microprocessors were inserted. It was commonly found alongside a secondary socket designed for a math coprocessor chip, in this case the Intel 80487....
, 168-pin Socket 1
Socket 1

Socket 1 was the second of a series of standard CPU socket created by Intel into which various x86 microprocessors were plugged. It was an upgrade to Intel's first standard Pin grid array socket and the first with an official designation....
, or Socket 2
Socket 2

Socket 2 was one of the series of CPU socket into which various x86 microprocessors were plugged. It was an updated Socket 1 with added support for Pentium Overdrive processors....
with voltage regulator
Vcore: 3.45 V
Clock rate: 133 MHz
Front side bus
Front side bus

In personal computers, the Front Side Bus is the bus that carries data between the central processing unit and the Northbridge .Depending on the processor used, some computers may also have a back side bus that connects the CPU to the CPU cache....
: 33 MHz

AMD 5x86

Models

Am5x86-P75 (X5-133)

External links