Founded in 1988 by engineers from Texas Instruments, Cyrix was a short-lived company whose brand name is no longer used by its current owner VIA Technologies. In the 1990s, Cyrix's competition with AMD created the market for budget central processing units (CPUs) by reducing the average selling price of personal computers. The competition ultimately forced Intel to release its Celeron line of budget processors and cut the prices of its faster processors more quickly. Before its purchase by VIA, Cyrix was a subsidiary of National Semiconductor until that company distanced itself from the CPU market.

Cyrix introduced the Fasmath coprocessor in 1989 with an initial clock frequency of 16 megahertz, but later upgraded the speed to include 20, 25, 33, and 40 megahertz versions. The chip is compatible with the Intel x87 coprocessors with regards to the instruction set and pin locations, making it a viable competitor with Intel math chips in the older 80x86 (XT, AT, and 386) microprocessor machines. The microscope utilized to capture the complete coprocessor die was operated in reflected light mode with differential interference contrast (DIC) optics and a first-order retardation plate. Eight individual sections of the die were photographed and mapped together to form a composite image of the entire integrated circuit.

The Cyrix line of Intel-compatible 486DX2 microprocessors were produced in the mid and late 1990s at clock speeds ranging from 50 to 80 megahertz, and contained an internal 8-kilobyte write-back cache designed to increase processor throughput. The integrated floating point unit was reported to execute instructions approximately 10 percent faster than comparible Intel processors. These chips were available in both 3 and 5-volt versions for portable and desktop computers and were fully compatible with DOS, Windows, OS/2, UNIX, and Novell NetWare applications.

Cyrix introduced the 6x86 microprocessor, code-named the M1, as a fifth generation x86-compatible alternative to the Intel Pentium. Similar to the Pentium, the 6x86 is a superscalar, native x86-execution processor that is pin and voltage-compatible with competing Intel and AMD microprocessors. The 6x86 incorporates several advanced architectural features, including out-of-order instruction completion, superior branch prediction, deepened internal pipelines, improved cache mapping, register renaming, and speculative execution.

486 DLC (49K) - Partial die shot showing the corner of the 486 DLC with bonding wires and bus connections using oblique illumination with red and blue gels.

486 DLC 40 (63K) - Partial die shot of the 486 DLC 40 showing bus connections on the body of the chip with oblique illumination using red and blue gels.

486 DLC 40 (67K) - Partial die shot of the 486 DLC 40 showing the numerous bus connections with oblique illumination using red, blue, and yellow gels.

486DX2 (74K) - Partial die shot of a 486DX2 wafer showing the intersection between the scribe lines and bus connections on four chips using oblique illumination with red, blue, and yellow gels.

6x86 (53K) - Partial die shot showing the corner of a 6x86 microprocessor and the bus connections with oblique illumination using blue and red gels.

6x86 (55K) - Partial die shot of the intersection between scribe lines on the 6x86 Polysilicon Layer wafer using oblique illumination with yellow, blue, and red gels.

M1 (54K) - Partial die shot of a Cyrix M1 wafer showing the intersection of the scribe line using dark field illumination with red and yellow gels.

M1 (57K) - Partial die shot of the Cyrix M1 wafer showing an intersection between scribe lines and bus connections using dark field illumination with red and yellow gels.

M1 (73K) - Partial die shot of the Cyrix M1 wafer showing an intersection between scribe lines and bus connections on the chips using dark field illumination with red and yellow gels.

M1 (52K) - Partial die shot of the M1 wafer showing mostly bus connections on one of the chips as well as the intersection of scribe lines with dark field illumination using red and yellow gels.

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