Intel 486SX Microprocessor

While the 80486 (DX version) is basically an enhanced 386 with an internal cache and math coprocessor, the Intel 486SX is the "economy model" lacking the math processor and internal cache. Originally issued as discounted DX chips that failed the cache and/or coprocessor tests, these defective silicon chips were soon released as their own design in a fashion similar to Intel's release of the 386SX following the higher-power 80386 processor (386DX).