The Cyrix Cx486SLC was Cyrix

Cyrix

Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas as a specialist supplier of high-performance math coprocessors for 286 and 386 microprocessors. The company was founded by former Texas Instruments staff members and had a long but troubled relationship...

's first CPU

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

 offering, released after years of selling coprocessor

Coprocessor

A coprocessor is a computer processor used to supplement the functions of the primary processor . Operations performed by the coprocessor may be floating point arithmetic, graphics, signal processing, string processing, or encryption. By offloading processor-intensive tasks from the main processor,...

s that competed with Intel's units and offered better performance at a comparable or lower price.

The 486SLC is based on the i386SX bus, and was intended as an entry-level chip to compete with the Intel 386SX and 486SX. Texas Instruments

Texas Instruments

Texas Instruments Inc. , widely known as TI, is an American company based in Dallas, Texas, United States, which develops and commercializes semiconductor and computer technology...

 manufactured the 486SLC for Cyrix, and also sold it under its own name; ti486SLC. Later, they also released their own version of the chip, the TI486SXLC which featured 8kB internal cache vs 1kB in the original Cyrix design. The similarly named IBM 486SLC, 486SLC2, 486SLC3 (16-bit version of IBM 486DLC aka Blue Lightning) and IBM 386SLC

386SLC

The 386SLC was an Intel-licensed version of the 386SX , developed and manufactured by IBM in 1991. It included power-management capabilities and an 8KB internal cache, which enabled it to yield comparable performance to 386DX processors of the same clock speed, which were considerably more expensive...

 are often confused with the Cyrix chips, but are not related and instead based on an Intel CPU core.

Introduced in May 1992, like the later and more famous Cyrix Cx5x86

Cyrix Cx5x86

Released in August 1995, four months before the more famous Cyrix 6x86, the Cyrix 5x86 was one of the fastest CPUs ever produced for Socket 3 computer systems...

 it was a hybrid CPU, incorporating features of a new CPU (in this case the Intel 80486

Intel 80486

The Intel 80486 microprocessor was a higher performance follow up on the Intel 80386. Introduced in 1989, it was the first tightly pipelined x86 design as well as the first x86 chip to use more than a million transistors, due to a large on-chip cache and an integrated floating point unit...

) while having a pin out similar to the existing 386SX, enabling existing board designs to be easily modified for the new chip. It ran at speeds of 20, 25, 33, and 40 MHz, although it had difficulty running reliably at 40 MHz using some operating systems. In December 1992 Cyrix also released the Cyrix Cx486SLC/e (25, 33 MHz) which offered power management, and a low voltage laptop version, the 3.3v Cyrix Cx486SLC/e-V (20, 25 MHz). In December 1993 Cyrix released a clock doubled version (25/50 MHz) cx486SLC2, as well as a clip-on upgrade for 386SX systems, the cx486SRx2 (16/33, 20/40 & 25/50 MHz).

The 486SLC can be described as a 386SX with the 486 instruction set and 1K of onboard L1 cache added. Unfortunately it inherited the 386SX's 24-bit address bus (16mb max. DRAM) , and 16-bit datapath which limited its memory bandwidth. Like the 386 and 486SX, it had no on-board math coprocessor

Coprocessor

A coprocessor is a computer processor used to supplement the functions of the primary processor . Operations performed by the coprocessor may be floating point arithmetic, graphics, signal processing, string processing, or encryption. By offloading processor-intensive tasks from the main processor,...

, but unlike the 486SX, it could make use of an Intel 287, 387SX or compatible coprocessor. Due to the limitations of the 386SX's bus and its smaller L1 cache, its performance could not compete with the 486SX when the latter was running on a full 32-bit bus.

The 486SLC was primarily used in very inexpensive low-end motherboard

Motherboard

In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

s and PC clones. Because of its low power consumption, it also saw use in laptop

Laptop

A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...

s. The 486SLC was also available as a 32-bit version based on the i386DX bus, see 486DLC.