The K5: AMD's Very Own Processor
In 1996, AMD released its fifth-generation processor, the K5. Compared to Intel’s Pentium, the K5 was technically more advanced, though it did have some faults. It’s especially interesting because of its RISC-based internal architecture that decoded x86 instructions into micro-instructions before executing them. The K5 had difficulty reaching high clock speeds and its FPU was a little weak. Still, in normal use, the K5 was a better performer than the Pentium and its PR was not just hype—a K5 clocked at 100 MHz was sold as a PR133 chip, meaning that AMD considered it as being equivalent in performance to a 133 MHz Pentium.
| Code name | SSA/5, 5k86 |
| Date released | 1996 |
| Architecture | 32-bits |
| Data bus | 64-bits |
| Address bus | 32-bits |
| Maximum memory | 4,096 MB |
| L1 cache | 16 KB + 8 KB |
| L2 cache | motherboard (FSB frequency) |
| Clock frequency | 75-133 MHz (PR75 - PR200) |
| FSB | 50-66 MHz |
| FPU | built-in |
| SIMD | no |
| Fabrication process | 500 - 350 nm |
| Number of transistors | 4.3 million |
| Power consumption | 11-16 W |
| Voltage | 3.52 V |
| Die surface area | 251 - 181 mm² |
| Connector | Socket 5 or 7 |
The use of the PR resulted in such oddities as a K5 PR90 and PR120 running at the same frequency (90 MHz) and a PR100 and PR133 both clocked at 100 MHz. Notice also that the CPU package informed buyers that a heat sink and fan were required—at that time, the use of such cooling devices was not yet common practice.