Athlon Classic

Athlon Classic launched on June 23, 1999. It showed superior performance compared to the reigning champion, Pentium III, in every benchmark.^[7]

Athlon Classic is a cartridge-based processor. The design, called Slot A, was quite similar to Intel's Slot 1 cartridge used for Pentium II and Pentium III; actually it used mechanically the same slot part as competing Intel CPUs (allowing motherboard manufacturers to save on costs) but reversed "upside-down" to prevent users putting in wrong CPUs (as they were completely signal incompatible). The cartridge allowed use of higher speed cache memory than is possible to put on the motherboard. Like Pentium II and the "Katmai"-core Pentium III, Athlon Classic used a 512 KiB secondary cache. This cache, again like its competitors, ran at a fraction of the core clock rate and had its own 64-bit bus, called a "backside bus" that allowed concurrent system front side bus and cache accesses.^[8] Initially the L2 cache was set for half of the CPU clock speed, on up to 700 MHz Athlon CPUs. Faster Slot-A processors were forced to compromise with cache clock speed and ran at 2/5 (up to 850 MHz) or 1/3 (up to 1 GHz).^[9] The SRAM available at the time was incapable of matching the Athlon's clock scalability, due both to cache chip technology limitations and electrical/cache latency complications of running an external cache at such a high speed.

The Slot-A Athlons were the first multiplier-locked CPUs from AMD. This was partly done to hinder CPU remarking being done by questionable resellers around the globe. AMD's older CPUs could simply be set to run at whatever clock speed the user chose on the motherboard, making it trivial to relabel a CPU and sell it as a faster grade than it was originally intended. These relabeled CPUs were not always stable, being overclocked and not tested properly, and this was damaging to AMD's reputation. Although the Athlon was multiplier locked, crafty enthusiasts eventually discovered that a connector on the PCB of the cartridge could control the multiplier. Eventually a product called the "Goldfingers device" was created that could unlock the CPU, named after the gold connector pads on the processor board that it attached to.^[10]

In commercial terms, the Athlon Classic was an enormous success — not just because of its own merits, but also because the normally dependable Intel endured a series of major production, design, and quality control issues at this time. In particular, Intel's transition to the 180 nm production process, starting in late 1999 and running through to mid-2000, suffered delays. There was a shortage of Pentium III parts. In contrast, AMD enjoyed a remarkably smooth process transition and had ample supplies available, causing Athlon sales to become quite strong.

Specifications

• K7 "Argon" (250 nm)
• K75 "Pluto/Orion" (180 nm)
• L1-Cache: 64 + 64 KiB (Data + Instructions)
• L2-Cache: 512 KiB, external chips on CPU module with 50, 40 or 33% of CPU-speed
• MMX, 3DNow!
• Slot A (EV6)
• Front side bus: 200 MT/s (100 MHz double-pumped)
• VCore: 1.6 V (K7), 1.6 - 1.8 V (K75)
• First release: June 23, 1999 (K7), November 29, 1999(K75)
• Clockrate: 500-700 MHz (K7), 550-1000 MHz (K75)