Imitation To Innovation: AMD’s Best CPUs – Part 1

AMD Clones Intel

The year is 1981, and Intel (see history of Intel processors) has just been chosen by IBM to supply the processor for the first personal computer. IBM wanted at least two CPU suppliers for its PC, and forced Intel to license its technology. And so it was that AMD became one of the first companies to sell an 8086 clone. AMD’s first processor went on sale in 1982. Because it was a licensed processor, the AMD 8086 (and 8088) was identical to Intel’s model.

AMD 8086

Code name	?
Date released	1982
Architecture	16-bits
Data bus	16-bits
Address bus	20-bits
Maximum memory	1 MB
L1 cache	no
L2 cache	no
Clock frequency	5-10 MHz
FSB	same as clock frequency
FPU	8087
SIMD	no
Fabrication process	3,000 nm
Number of transistors	29,000
Power consumption	?
Voltage	5 V
Die surface area	16 mm²
Connector	40 pins

Note the “© Intel” on the processor, made by AMD.

Am286: Manufactured Under License, But Faster

AMD’s Am286, a clone of the Intel 80286 manufactured under license, was identical to the chip from Intel, but it had a big advantage: its higher clock speed. Whereas Intel’s 286s topped out at 12.5 MHz, AMD sold 20 MHz versions. Because the 286 was more economical than the 386, whose innovations weren’t fully exploited for several years, AMD was already the value choice more than 20 years ago.

Am286

Code name	?
Date released	1983
Architecture	16-bits
Data bus	16-bits
Address bus	24-bits
Maximum memory	16 MB
L1 cache	no
L2 cache	no
Clock frequency	8-20 MHz
FSB	same as clock frequency
FPU	80287
SIMD	no
Fabrication process	1,500 nm
Number of transistors	134,000
Power consumption	?
Voltage	5 V
Die surface area	49 mm²
Connector	68 pins

Am386: A 40-MHz 386

In 1991, AMD released its 386 processor. Like its predecessors, this model was identical to the Intel versions. AMD was licensed to produce clones of Intel products, right down to the microcode (the CPU’s firmware). This processor had two notable features. First, it was faster than the Intel model—40 MHz compared to a top speed of 33 MHz at Intel—and it was the first to sport the Windows Compatible logo on the package.

Am386

Code name	?
Date released	1991
Architecture	32-bits
Data bus	32-bits
Address bus	32-bits
Maximum memory	4,096 MB
L1 cache	no
L2 cache	no
Clock frequency	12-40 MHz
FSB	same as clock frequency
FPU	80387
SIMD	no
Fabrication process	1,500 – 1,000 nm
Number of transistors	275,000
Power consumption	2 W (33 MHz)
Voltage	5 V
Die surface area	42 mm²
Connector	132 pins

Am486: The Last Clone

The 486 was the last clone of an Intel processor. AMD produced 486s in two different versions—one with microcode by Intel and another with microcode by AMD, because the company was having legal hassles with Intel by that point. In addition to processors sold under the 486 designation, AMD also marketed an AMD 5×86, which was a 486 with a 4x clock multiplier. Running at 133 MHz, this model was compatible with 486 motherboards, but had the performance of a Pentium 75. It was with the 5×86 that AMD began using the famous “Pentium Rating” (5×86 PR 75), which it would stay with up to and including the Athlon 64 X2.

Am486 / 5×86

Code name	?	X5
Date released	1993	1995
Architecture	32-bits	32-bits
Data bus	32-bits	32-bits
Address bus	32-bits	32-bits
Maximum memory	4,096 MB	4,096 MB
L1 cache	8 KB	16 KB
L2 cache	motherboard (FSB frequency)	motherboard (FSB frequency)
Clock frequency	16-120 MHz	133 MHz
FSB	16-50 MHz	33 MHz
FPU	built-in	built-in
SIMD	no	no
Fabrication process	1,000 – 800 nm	350 nm
Number of transistors	1,185,000	?
Power consumption	?	?
Voltage	5 V–3.3 V	3.45 V
Die surface area	81 – 67 mm²	?
Connector	168 pins	168 pins

The K5: AMD’s Very Own Processor

In 1996, AMD released its fifth-generation processor, the K5. Compared to Intel’s Pentium, the K5 was technically more advanced, though it did have some faults. It’s especially interesting because of its RISC-based internal architecture that decoded x86 instructions into micro-instructions before executing them. The K5 had difficulty reaching high clock speeds and its FPU was a little weak. Still, in normal use, the K5 was a better performer than the Pentium and its PR was not just hype—a K5 clocked at 100 MHz was sold as a PR133 chip, meaning that AMD considered it as being equivalent in performance to a 133 MHz Pentium.

AMD K5

Code name	SSA/5, 5k86
Date released	1996
Architecture	32-bits
Data bus	64-bits
Address bus	32-bits
Maximum memory	4,096 MB
L1 cache	16 KB + 8 KB
L2 cache	motherboard (FSB frequency)
Clock frequency	75-133 MHz (PR75 – PR200)
FSB	50-66 MHz
FPU	built-in
SIMD	no
Fabrication process	500 – 350 nm
Number of transistors	4.3 million
Power consumption	11-16 W
Voltage	3.52 V
Die surface area	251 – 181 mm²
Connector	Socket 5 or 7

The use of the PR resulted in such oddities as a K5 PR90 and PR120 running at the same frequency (90 MHz) and a PR100 and PR133 both clocked at 100 MHz. Notice also that the CPU package informed buyers that a heat sink and fan were required—at that time, the use of such cooling devices was not yet common practice.

The K6: AMD Extends Its Range

In 1997, AMD released a new processor: the K6. Unlike the K5, which was created by AMD, the K6 was the result of the work done by NexGen on the Nx686. This processor was compatible with Socket 7 (Pentium) motherboards and offered very good performance compared to Intel’s Pentium II processors, at a much lower price. The K6’s FPU was still a little weak compared to Intel’s. A 250 nm version of the K6, called Little Foot, came out in 1998.

Also in 1998, AMD announced the K6-2, a processor that used a faster bus (100 MHz) and had improved SIMD performance. It also had one more MMX unit than the K6 and a new instruction set, 3DNow!, for floating-point calculations (MMX handled only integers). The K6-2 (400 and up) was a big success because it was a good upgrade solution for owners of Pentium MMX platforms—by using the 2X multiplier on a motherboard with a 66 MHz bus, the processor was in fact operating at 6X (400 MHz), which permitted a significant gain in speed at a lower upgrade cost.

Finally, in 1999, AMD released the third version of the K6, the K6-III. The main difference from the K6-2 version was an on-chip 256 KB cache. The K6-III was very fast, but also very costly to produce, and was quickly replaced by the Athlon (K7).

AMD K6, K6-2, K6-III

Code name	K6, Little Foot (250 nm)	K6-3D, Chomper	Sharptooth
Date released	1997/1998	1998	1999
Architecture	32-bits	32-bits	32-bits
Data bus	64-bits	64-bits	64-bits
Address bus	32-bits	32-bits	32-bits
Maximum memory	4,096 MB	4,096 MB	4,096 MB
L1 cache	32 KB + 32 KB	32 + 32 KB	32 + 32 KB
L2 cache	motherboard (FSB frequency)	motherboard (FSB frequency)	256 KB (CPU frequency)
L3 cache	no	no	motherboard (FSB frequency)
Clock frequency	166-300 MHz	300-550 MHz	400-450 MHz
FSB	50-66 MHz	66-100 MHz	100 MHz
FPU	built-in	built-in	built-in
SIMD	MMX	MMX, 3DNow!	MMX, 3DNow!
Fabrication process	350 – 250 nm	250 nm	250 nm
Number of transistors	8.8 million	9.3 million	21.3 million
Power consumption	12-28 W	13-25 W	10-17 W
Voltage	2.2–2.9 V–3.2 V	2.2–2.4 V	2.2–2.4 V
Die surface area	157-68 mm²	81 mm²	118 mm²
Connector	Socket 7	Socket 7 / Super Socket 7	Super Socket 7

AMD also marketed K6-2+ and K6-3+ processors, mainly for portable PCs. These used a 180 nm fab process and had an on-chip 128 KB (K6-2+) or 256 KB (K6-3+) L2 cache.

K7/Athlon: A Killer

In 1999, AMD released its seventh-generation processor, the K7, later renamed Athlon. This chip did away with the drawbacks of earlier models and finally had an FPU worthy of the name—in fact, it was even better than Intel’s. The Athlon was the fastest x86 processor and had many strong points, including a fast FSB—the EV6, used in the first Alpha processors—and high performance numbers. The only real problem came not from the processor but from the chipsets: neither the AMD nor Via models could compete with Intel’s chipsets (like the famous 440BX). The K7 used Slot A (competing with Intel’s Slot 1) and had a Level 2 cache with a variable divider (1/2, 2/5 or 1/3).

AMD Athlon (K7, K75)

Code name	Argon (K7)	Pluto, Orion (K75)
Date released	1999	1999
Architecture	32-bits	32-bits
Data bus	64-bits	64-bits
Address bus	32-bits	32-bits
Maximum memory	4,096 MB	4,096 MB
L1 cache	64 KB + 64 KB	64 KB + 64 KB
L2 cache	Slot A (1/2 CPU)	Slot A (1/2, 2/5 or 1/3 CPU)
Clock frequency	500-700 MHz	550-1000 MHz
FSB	100 MHz (DDR)	100 MHz (DDR)
FPU	built-in	built-in
SIMD	MMX, Enhanced 3DNow!	MMX, Enhanced 3DNow!
Fabrication process	250 nm	180 nm
Number of transistors	22 million	22 million
Power consumption	42-50 W	31-65 W
Voltage	1.6 V	1.6–1.8 V
Die surface area	184 mm²	102 mm²
Connector	Slot A	Slot A

Just as a side note, it was AMD who was the first to announce (and market) a 1 GHz processor with the Athlon (two days before Intel’s 1 GHz Pentium III).

AMD Improves the Athlon: Thunderbird, XP, and more.

AMD knew it had a winner with the K7 architecture and improved it little by little, increasing the frequency and using finer fab processes. The Thunderbird core employed a 180 nm process and had 256 KB of on-chip cache. The Palomino design introduced support for SSE. The Athlon XP changed the package and reinstated PR numbers. The Thoroughbred was an Athlon XP using a 130 nm fab process (with a 256 KB cache). Barton had a 512 KB cache and also used a 130 nm process. Athlon XP and subsequent models used the PR number instead of a clock frequency designation.

AMD Athlon

Code name	Thunderbird	Palomino/XP	Thoroughbred	Barton
Date released	2000	2001	2002	2003
Architecture	32-bits	32-bits	32-bits	32-bits
Data bus	64-bits	64-bits	64-bits	64-bits
Address bus	32-bits	32-bits	32-bits	32-bits
Maximum memory	4,096 MB	4,096 MB	4,096 MB	4,096 MB
L1 cache	64 KB + 64 KB	64 KB + 64 KB	64 KB + 64 KB	64 KB + 64 KB
L2 cache	256 KB (CPU frequency)	256 KB (CPU frequency)	256 KB (CPU frequency)	512 KB (CPU frequency)
Clock frequency	650-1,400 MHz	1,000-1,733 MHz	1,200-2,250 MHz	1,400-2,200 MHz
FSB	100/133 MHz (DDR)	133 MHz (DDR)	133/166 MHz (DDR)	166/200 MHz (DDR)
FPU	built-in	built-in	built-in	built-in
SIMD	MMX, Enhanced 3DNow!	MMX, Enhanced 3DNow!, SSE	MMX, Enhanced 3DNow!, SSE	MMX, Enhanced 3DNow!, SSE
Fabrication process	180 nm	180 nm	130 nm	130 nm
Number of transistors	37 million	37.5 million	37.2 million	54.3 million
Power consumption	38-72 W	46-72 W	49-68 W	60-76 W
Voltage	1.7-1.75 V	1.75 V	1.5-1.65 V	1.65 V
Die surface area	120 mm²	129.26 mm²	84.66 mm²	100.99 mm²
Connector	Socket A	Socket A	Socket A	Socket A

We should mention that AMD also produced versions for servers (Athlon MP) and for laptops (Athlon 4, Athlon XP Mobile), as well as the Geode NX (130 nm and a 256 KB cache). AMD marketed the Thorton (130 nm, 512 KB of cache, 256 KB of which was disabled) and planned on Trinidad, an Athlon using a 90 nm process. There were more PR oddities: the Athlon XP 2600+ was clocked at 1,900, 1,917, 2,000, 2,083, or 2,133 MHz depending on the version, for instance