Intel's first dual-core chip was a hastily concocted design that was rushed out the door in hopes of beating rival AMD to the punch, an Intel engineer told attendees at the Hot Chips conference today.
Following the company's realisation that its single-core processors had hit a wall, Intel engineers plunged headlong into designing the Smithfield dual-core chip in 2004, but they faced numerous challenges in getting it to market, according to Jonathan Douglas, a principal engineer at Intel.
"We faced many challenges from taking a design team focused on making the highest-performing processors possible to one focused on multicore designs," Douglas said.
Intel was unable to design a new memory bus in time for the dual-core chip, so it kept the same bus structure that older Pentium 4 chips used. This could support two separate single-core processors, but it was far less efficient than either the dual-independent buses that will appear on the Paxville processors or the integrated memory controller used on AMD's chips. The memory bus or frontside bus on Intel's chips is used to connect the processor to memory.
All of Intel's testing tools and processes had been designed for single-core chips, Douglas said. As a result, the company had to quickly devise a testing methodology for dual-core chips that could measure the connections between both cores.
In addition, engineers had to design a package for the Pentium D chips that could accommodate both cores. "We're putting two cores in one package; it's like trying to fit into the pair of pants you saved from college," Douglas said.
The company's Pentium D processors consist of two Pentium 4 cores placed closely together on a single silicon die. The design creates some problems, since dual-core processors must have some logic that coordinates the actions of both cores. This complication led to signalling problems that needed to be overcome.
Ultimately, Intel completed the Smithfield processor core in nine months. By the company's standards, that is an extremely short development time for a major processor design, said Kevin Krewell, editor in chief of The Microprocessor Report in San Jose, California.
"Most designs take years," Krewell said. "But it was very important for them to get back in the game and have a road map."
One reason for Intel's aggressive schedule for developing Smithfield was the company's need to respond to AMD's actions, Douglas said, without mentioning AMD by name. "We needed a competitive response. We were behind," he said.
Despite the rush, Smithfield was good enough to get Intel into the dual-core era, Krewell said. "It's not an optimal solution, but it's a viable solution. It works, and it works reasonably well," he said.