486SX

The Intel 486SX, often pronounced "four eighty-six SX," was a lower-cost version of the Intel 486 microprocessor. Released in 1991, it was designed to offer a more affordable entry point into the 486 performance class. The primary difference between the 486SX and its sibling, the 486DX, was the disabling of the integrated floating-point unit (FPU) on the 486SX. This meant that while the 486SX could perform integer calculations at 486 speeds, it lacked the dedicated hardware for floating-point math operations.

To perform floating-point calculations, systems with a 486SX processor would rely on software emulation or require the installation of a separate coprocessor, typically the Intel 80487SX. This coprocessor was essentially a full 486DX chip with some minor differences in pinout and detection logic. The 486SX was available in various clock speeds, starting with 16 MHz and later increasing to 20, 25, and 33 MHz.

The 486SX was successful in the market by providing a significant performance upgrade over the older 386 processors at a more accessible price point. It became a popular choice for mainstream desktop computers and enabled the widespread adoption of the 32-bit x86 architecture in a broader range of consumer products. While it was later superseded by more powerful and integrated Intel processors, the 486SX played a crucial role in the evolution of personal computing.