Yonah, Merom, and Conroe: Confused by Intel's Code Names?

- 2006.03.17

Ed Hurtley is a former Intel employee. He shares the history of Intel's CPU code names and what future Intel CPUs will deliver.

With the ongoing switch to Intel CPUs, Apple fans have been forced to learn a whole new batch of code names. Intel is famous for using code names for each of its processors, which, unlike Apple's code names, are publicly used by Intel executives, often years in advance of a product's release.

For example, the current crop of Intel Macs uses a processor that went by the code name "Yonah" during development. This processor now goes by the names Core Duo and Core Solo, depending on the configuration. Coming up are a trio of related processors code named "Merom", "Conroe", and "Woodcrest".

What do these names mean?

First, a bit of Intel history. During early days of processor development, Intel's CPUs didn't have code names, they just had model numbers. 4004, 8088, 80286, etc.

Since a random string of numbers can't be trademarked, Intel decided to come up with names for them. The first attempt at this was to shorten the processor's model number. Thus, the 80486 became the i486DX - not very interesting, but it could be trademarked.

During development of their fifth generation processor, Intel not only did away with the model number as a public name, but as a code name as well.

As marketing hadn't yet come up with a good public name for the upcoming fifth generation CPU, Intel engineers named the chip the P5. Later, marketing came up with the name Pentium™.

At about this time, Intel broke processor development into two groups - one group based in California, the other in Oregon - and code names took on place names. So the first Pentium II processor acquired the code name "Klamath" after a river in Oregon.

For many processor generations, processor cores were named after rivers in Oregon and later on for other locations where Intel had facilities.

After the release of the Pentium 4 Processor, Intel saw the need to develop a lower power processor for mobile use. They tasked this to their division in Haifa, Israel.

This team was so successful with their design, the Pentium M (code name "Banias") that Intel eventually decided to abandon the Pentium 4 line for a new core designed as a hybrid combining features from both the Pentium 4 and Pentium M lines.

This new line's first series of chips will be Merom, Conroe, and Woodcrest.

Back to the present. We have the new Intel-based iMac, MacBook Pro, and Mac mini using Intel's Core Duo and Core Solo chips, code named Yonah. These chips are a direct descendent of the Banias/Pentium M chip.

The big advance that Yonah made over its predecessor, "Dothan", was dual-cores. In contrast to other dual-core designs, Yonah has a shared level 2 cache. Most current dual core designs are more like having two single processors attached on one piece of silicon. Yonah's design shares many internal components.

The next generation of processors are all based on one similar core with slightly different features for different uses.

Merom is the successor to the mobile Yonah chip. The big advancement it adds over Yonah is 64-bit mode.

Conroe is the chip aimed at the desktop market. It will replace the single-core Pentium 4 and its dual-core equivalent, the Pentium D. Based on the same core technology as Merom, it will have slower clock speeds than Pentium 4, yet be faster in actual processing capability (remember the core truth of the Megahertz Myth - a more efficient CPU can outperform a less efficient one even when the less efficient one runs at a faster clock speed).

Conroe will likely have less power-saving technologies to make it cheaper, although this hasn't yet been confirmed.

Woodcrest is the workstation/server chip. It will replace Intel's Xeon line of processors in the multiprocessor market. It also will likely have fewer power-saving features enabled and may (also not confirmed) support HyperThreading, a feature that is lacking on Intel's current mobile chips (as well as all but the most expensive dual-core desktop chips).

More information on Intel's code names can be seen on the Wikipedia entry for Intel Core Microarchitecture, where you'll also see code names like Penryn, Wolfdale, Clovertown, Perryville, and Dunnington. 

Further reading: Intel Core Microarchitecture, Wikipedia