K9 was a planned microarchitecture developed by AMD as a successor to K8. The K9 codename might cover multiple projects at AMD. A deep pipeline design led by Mitch Alsup as Chief Architect, another one intended to bring massive parallelism and finally, using K9 as a codename for dual-core K8.
The whole set of intended features and the exact reasons AMD cancelled K9 remain unknown.
Deep pipeline design
According to Alsup, it was designed to be close to 95% of original K8 IPC but reach 5GHz frequency in a 35 nm process. At the time of cancellation most of the logic was running in SPICE at 5GHz and majority of the layout was done.
The K9 pipeline was dual-quad issue. It was described by Alsup as: "K9 fetched 8 instructions every other cycle and made 2 branch predictions associated with 3 next fetch addresses every other cycle. K9 issued 4 instructions per cycle and took 2 cycles to issue a fetch width."
Reportedly, the design was cancelled due to leakage current problems amplified by necessity to embrace the multi-core era. K9's DDR2 SDRAM controller was later used in K8 Rev F and its northbridge technology got put in K8 Rev G.
- Anand Lal Shimpi, Why is Barcelona late? - AMD - The Road Ahead, anandtech.com. Retrieved on December 1, 2018