AMD K5
Encyclopedia
The K5 was AMD's
Advanced Micro Devices
Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...

 first x86
X86 architecture
The term x86 refers to a family of instruction set architectures based on the Intel 8086 CPU. The 8086 was launched in 1978 as a fully 16-bit extension of Intel's 8-bit based 8080 microprocessor and also introduced segmentation to overcome the 16-bit addressing barrier of such designs...

 processor to be developed entirely in-house. Introduced in March 1996, its primary competition was Intel's
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...

 Pentium microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

. The K5 was an ambitious design, closer to a Pentium Pro than a Pentium regarding technical solutions and internal architecture. However, the final product was closer to the Pentium regarding performance, although faster clock for clock compared to the Pentium.

Technical details

The K5 was based upon an internal highly parallel 29k
AMD Am29000
The AMD 29000, often simply 29k, was a popular family of 32-bit RISC microprocessors and microcontrollers developed and fabricated by Advanced Micro Devices . They were, for a time, the most popular RISC chips on the market, widely used in laser printers from a variety of manufacturers...

 RISC processor architecture with an x86 decoding front-end. The K5 offered good x86 compatibility. All models had 4.3 million transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

s, with five integer units that could process instructions out of order
Out-of-order execution
In computer engineering, out-of-order execution is a paradigm used in most high-performance microprocessors to make use of instruction cycles that would otherwise be wasted by a certain type of costly delay...

 and one floating point unit. The branch target buffer was four times the size of the Pentium's and register renaming
Register renaming
In computer architecture, register renaming refers to a technique used to avoid unnecessary serialization of program operations imposed by the reuse of registers by those operations.-Problem definition:...

 improved parallel performance of the pipelines. The chip's speculative execution
Speculative execution
Speculative execution in computer systems is doing work, the result of which may not be needed. This performance optimization technique is used in pipelined processors and other systems.-Main idea:...

 of instructions reduced pipeline stalls. It had a 16 KB, four-way set associative instruction cache and an 8 KB data cache. The K5 lacked MMX instructions, which Intel started offering in its Pentium MMX processors that were launched in early 1997.

Performance

The K5 project represented an early chance for AMD to take technical leadership from Intel. Although the chip addressed the right design concepts, the actual engineering implementation had its issues. The low clock rates were, in part, due to AMD's limitations as a "cutting edge" manufacturing company at the time, in part due to the design itself (many levels of logic, thus slowing it down). Having a branch prediction unit four times the size of the Pentium, yet reportedly not delivering superior performance is an example of how the actual implementation fell short of the project's goals. Additionally, while the K5's floating point performance was better than that of the Cyrix 6x86
Cyrix 6x86
The Cyrix 6x86 is a sixth-generation, 32-bit 80x86-compatible microprocessor designed by Cyrix and manufactured by IBM and SGS-Thomson. It was originally released in 1996.-Architecture:...

, it was weaker than that of the Pentium. Because it was late to market and did not meet performance expectations, the K5 never gained the acceptance among large computer manufacturers that the Am486
Am486
The Am486 is a 80486-class family of computer processors 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.While...

 and AMD K6
AMD K6
The K6 microprocessor was launched by AMD in 1997. The main advantage of this particular microprocessor is that it was designed to fit into existing desktop designs for Pentium branded CPUs. It was marketed as a product which could perform as well as its Intel Pentium II equivalent but at a...

 enjoyed.

Models

There were two sets of K5 processors, internally called the SSA/5 and the 5k86, both released with the K5 label. The "SSA/5" line ran from 75 to 100 MHz (5K86 P75 to P100, later K5 PR-75 to PR100); the "5k86" line ran from 90 to 133 MHz. However, AMD used what it called a 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.-Branding:...

, or performance rating, to label the chips according to their equivalence to a Pentium of that clock speed. Thus, a 116 MHz chip from the second line was marketed as the "K5 PR166". Manufacturing delays caused the PR200's arrival to unfortunately nearly align with the release of K6. Since AMD did not want the two chips competing, the K5-PR200 only arrived in small numbers.

SSA/5

  • Sold as 5K86 P75 to P100, later as K5 PR75 to PR100
  • 4.3 million Transistors in 500 or 350 nm
  • L1-Cache: 8 + 16 KB (Data + Instructions)
  • Socket 5
    Socket 5
    Socket 5 was created for the second generation of Intel P5 Pentium processors operating at speeds from 75 to 120 MHz as well as certain Pentium OverDrive and Pentium MMX processors with core voltage 3.3 V. Consisting of 320 pins, this was the first socket to use a staggered pin grid array, or...

     and Socket 7
    Socket 7
    Socket 7 is a physical and electrical specification for an x86-style CPU socket on a personal computer motherboard. The socket supersedes the earlier Socket 5, and accepts P5 Pentium microprocessors manufactured by Intel, as well as compatibles made by Cyrix/IBM, AMD, IDT and others.Socket 7 was...

  • VCore: 3.52V
  • Front side bus
    Front side bus
    A front-side bus is a computer communication interface often used in computers during the 1990s and 2000s.It typically carries data between the central processing unit and a memory controller hub, known as the northbridge....

    : 50 (PR75), 60 (PR90), 66 MHz (PR100)
  • First release: March 27, 1996
  • Clockrate: 75, 90, 100 MHz

5k86

  • Sold as K5 PR120 to PR166 (PR200)
  • 4.3 million Transistors in 350 nm
  • L1-Cache: 8 + 16 KB (Data + Instructions)
  • Socket 5
    Socket 5
    Socket 5 was created for the second generation of Intel P5 Pentium processors operating at speeds from 75 to 120 MHz as well as certain Pentium OverDrive and Pentium MMX processors with core voltage 3.3 V. Consisting of 320 pins, this was the first socket to use a staggered pin grid array, or...

     and Socket 7
    Socket 7
    Socket 7 is a physical and electrical specification for an x86-style CPU socket on a personal computer motherboard. The socket supersedes the earlier Socket 5, and accepts P5 Pentium microprocessors manufactured by Intel, as well as compatibles made by Cyrix/IBM, AMD, IDT and others.Socket 7 was...

  • VCore: 3.52V
  • Front side bus
    Front side bus
    A front-side bus is a computer communication interface often used in computers during the 1990s and 2000s.It typically carries data between the central processing unit and a memory controller hub, known as the northbridge....

    : 60 (PR120/150), 66 MHz
  • First release: October 7, 1996
  • Clockrate: 90 (PR120), 100 (PR133), 105 (PR150), 116.6 (PR166), 133 MHz (PR200)

Further reading

  • Gwennap, Linley (25 March 1996). "AMD Ships Pentium Competitor". Microprocessor Report.
  • Slater, Michael (24 October 1994). "AMD's K5 Designed to Outrun Pentium". Microprocessor Report.
  • Slater, Michael (8 May 1995). "AMD K5 Volume Slips into 1996". Microprocessor Report.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK