Cyrix Cx486DLC

The Cyrix Cx486DLC was an early 486 CPU from Cyrix, intended to compete with the Intel 486SX and DX. Texas Instruments, who manufactured the 486DLC for Cyrix, later released its own version of the chip, the TI486SXL, with 8 kB internal cache vs 1 kB of the original Cyrix design. The similarly named IBM 486DLC, 486DLC2, 486DLC3 (aka Blue Lightning) are often confused with the Cyrix chips, but are not related and are instead based on Intel's i486 design.

Introduced in June 1992, like the later and more famous Cyrix Cx5x86 it was a hybrid CPU, incorporating features of a new CPU (in this case the Intel 80486) while plugging into its predecessor's (386DX) socket. It ran at speeds of 25, 33, and 40 MHz.

The 486DLC can be described as a 386DX with the 486 instruction set and 1 KB of on-board L1 cache added. Because it used the 386DX bus (unlike its 16-bit cousin, the 486SLC) it was a fully 32-bit chip. Like the 386 and 486SX, it had no on-board math coprocessor, but unlike the 486SX, it could make use of an Intel 387DX or compatible numeric coprocessor. A few 486SX motherboards also provided i387 sockets, but this feature was a very much a rarity. Due to the smaller L1 cache, the 486DLC could not compete on a clock-for-clock basis with the 486SX, but a 33 MHz 486DLC could keep pace with a 25 MHz 486SX, cost less, and offered the ability to upgrade further with the addition of an inexpensive math coprocessor.