Imitation To Innovation: AMD's Best CPUs

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 5x86, 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 5x86 that AMD began using the famous “Pentium Rating” (5x86 PR 75), which it would stay with up to and including the Athlon 64 X2.

Am486 / 5x86
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