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The 486: An FPU And Multipliers Too

Intel's 15 Most Unforgettable x86 CPUs
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The 486 is emblematic of a certain generation who were first discovering computers. In fact, the very famous 486 DX2/66 was long considered the minimum configuration for gamers. This processor, released in 1989, ushered in several interesting new features, like an on-chip FPU, data cache, and the first clock multiplier. The former consisted of an x87 coprocessor built into the 486 DX (not SX) series. An 8 KB Level 1 cache was built into the processor (write-through type, then write-back with slightly better performance). There was also the possibility of a Level 2 cache on the motherboard (at the bus frequency).

The second generation of 486s had a CPU multiplier, since the processor operated faster than the FSB, with DX2 (2x multiplier) and DX4 (3x multiplier) versions. Another anecdote: the “487SX” sold as an FPU for the 486SX was actually a full 486DX that disabled and took the place of the first processor.

Intel 80486 DX
Code name P4, P24, P24C
Date released 1989
Architecture 32 bits
Data bus 32 bits
Address bus 32 bits
Maximum memory 4096 MB
L1 cache 8 KB
L2 cache Motherboard (FSB frequency)
Clock frequency 16-100 MHz
FSB 16-50 MHz
FPU On chip
SIMD No
Fabrication process 1,000–800 nm
Number of transistors 1,185,000
Power consumption N/A
Voltage 5 V–3.3 V
Die surface area 81 - 67 mm²
Connector 168 pins

The DX4 had a 16 KB cache and a few more transistors: 1.6 million. This processor, using a 600 nm process and measuring 76 mm², consumed less power than the original 486 (at a voltage of 3.3 V).

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