The Cyrix Cx486SLC is a x86 microprocessor that was developed by
Cyrix
Cyrix Corporation was a microprocessor developer that was founded in 1988 in Richardson, Texas, as a specialist supplier of floating point units for 286 and 386 microprocessors. The company was founded by Tom Brightman and Jerry Rogers. Ter ...
. It was one of Cyrix's first
CPU offerings, released after years of selling
math coprocessors that competed with
Intel's units and offered better performance at a comparable or lower price. It was announced in March of 1992, and released 2 months later in May, with a price of $119. It was priced competitively against the
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer compo ...
486SX, causing Intel to lower the price of their chip from $286 to $119 in just days.
Specifications
The 486SLC is based on the
i386SX
The Intel 386, originally released as the 80386 and later renamed i386, is the third-generation x86 architecture microprocessor from Intel. It was the first 32-bit processor in the line, making it a significant evolution in the x86 archite ...
bus, and was intended as an entry-level chip to compete with the Intel 386SX and 486SX.
SGS-Thomson and
Texas Instruments
Texas Instruments Incorporated (TI) is an American multinational semiconductor company headquartered in Dallas, Texas. It is one of the top 10 semiconductor companies worldwide based on sales volume. The company's focus is on developing analog ...
manufactured the 486SLC for Cyrix. Texas Instruments also sold it under its own name as TX486SLC. Later, Texas Instruments also released their own version of the chip, the TI486SXLC which featured 8KB internal cache vs 1KB in the original Cyrix design. These chips went under the name Potomac, and Cyrix would receive full royalties for them. The similarly named
IBM 486SLC
The 386SLC is an Intel-licensed version of the 386SX (32-bit internal, 16-bit external, 24-bit memory addressing), developed and manufactured by IBM in 1991. It included power-management capabilities and an 8KB internal CPU cache, which enabled ...
, 486SLC2, 486SLC3 (16-bit external bus version of IBM 486DLC aka Blue Lightning) and
IBM 386SLC 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
The Cyrix 5x86 is a line of x86 microprocessors designed by Cyrix and released on June 5 of 1995. Cyrix, being a fabless company, had the chips manufactured by IBM. The line came out about 5 months before the more famous Cyrix 6x86. The Cyrix ...
it was a hybrid CPU, incorporating features of a new CPU (in this case the
Intel 80486
The Intel 486, officially named i486 and also known as 80486, is a microprocessor introduced in 1989. It is a higher-performance follow-up to the i386, Intel 386. It represents the fourth generation of binary compatible CPUs following the Inte ...
) 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 (16 MB max. DRAM), and 16-bit datapath which limited its memory bandwidth. Like the 386 and 486SX, it had no on-board
x87 math coprocessor, but unlike the 486SX, it could make use of an Intel i287, 387SX or compatible
x87 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
A motherboard, also called a mainboard, a system board, a logic board, and informally a mobo (see #Nomenclature, "Nomenclature" section), is the main printed circuit board (PCB) in general-purpose computers and other expandable systems. It ho ...
s and PC clones. Because of its low power consumption, it also saw use in
laptop
A laptop computer or notebook computer, also known as a laptop or notebook, is a small, portable personal computer (PC). Laptops typically have a Clamshell design, clamshell form factor (design), form factor with a flat-panel computer scree ...
s. The 486SLC was also available as a 32-bit version based on the i386DX bus, see
486DLC
The Cyrix Cx486DLC is an x86 desktop microprocessor developed by Cyrix. It was Cyrix's second CPU offering, released years after selling math coprocessors that competed with Intel's units and offered better performance at a comparable or lower ...
.
Texas Instruments TX486SLC.jpg, TI486SLC
Evergreen Technologies Inc., 486 SuperChip (16118395508) (cropped).jpg, Cyrix Cx486SLC with 87SLC co-processor (top view)
Evergreen Technologies Inc., 486 SuperChip (16305942855) (cropped).jpg, Cyrix Cx486SLC with 87SLC co-processor (bottom view)
KL TI 486SXLC.jpg, TI486SXLC
Versions
Cx486SLC/SLC2
The base 486SLC, which had speeds of 20, 25, 33, and 40 MHz with 1 KB of cache and a 16-bit bus. A later version, the 486SLC2, ran at 50 MHz.
TI486SLC
TI's rebranded version of the Cx486SLC.
TI486SXLC/SXLC2
The TI486SXLC/SXLC was Texas Instrument's version of the Cx486SLC. They had 8 KB of cache over the original 1 KB, a 32-bit internal data bus, and supported clock-doubling.
Cx486SRx2
Intel v. Cyrix lawsuit
Before even announcing the chip in March of 1992, Intel filed a lawsuit against Cyrix for patent infringement. Prior to this, Cyrix asked for a declaratory judgement that would prevent Intel from suing Cyrix.
Texas Instruments joined the suit shortly after with an intervene, siding with Cyrix.
Cyrix used SGS-Thomson as a second manufacturer of the chip, as the company had license to use Intel's patents. Intel however claimed the licence SGS-Thomson had was never intended to allow companies like Cyrix to circumvent Intel patents, which Intel stated was "patent laundering".
The lawsuit, which concluded in 1994, stated:
''Cyrix is entitled to judgment in its favor on its affirmative defenses of patent exhaustion and implied license based on the use or resale of its claim 1 microprocessors purchased from TI and ST.''
See also
*
Cyrix Cx486DLC
The Cyrix Cx486DLC is an x86 desktop microprocessor developed by Cyrix. It was Cyrix's second CPU offering, released years after selling math coprocessors that competed with Intel's units and offered better performance at a comparable or lower ...
- Cyrix's next CPU offering, released in June of 1992.
References
*{{cite web, url=http://www.tweaktown.com/reviews/22/via_c3_aka_cyrix_3/index.html , title=VIA C3 (AKA Cyrix 3) , date= 5 July 2001 , website=TweakTown , archive-url=https://web.archive.org/web/20200729035127/https://www.tweaktown.com/reviews/22/via_c3_aka_cyrix_3/index.html , archive-date=29 July 2020 Mentions Cyrix Cx486SLC in the Introduction.
486SLC
The Cyrix Cx486SLC is a x86 microprocessor that was developed by Cyrix. It was one of Cyrix's first Central processing unit, CPU offerings, released after years of selling Floating-point unit, math coprocessors that competed with Intel, Intel's ...
Computer-related introductions in 1992
X86 microarchitectures