When it comes to CPU's, the names Intel and AMD normally spring to mind. In the notebook sector, Intel has a wide range of mobile CPUs available, but so far AMD has no Athlon/Duron solution that meets the thermal constraints of notebooks. In addition to these 2 big names, the VIA/Cyrix brand of value CPUs might also be familiar to many. However, Transmeta, a Santa Clara based company, is relatively unknown.
Transmeta's Crusoe TM5600 processor is much more then just a CPU.
The designers put a CPU core into the 474-pin BGA package, including Caches and Northbridge. The Transmeta chip supports 100-133MHz DDR SDRAM and 66-133MHz SDRAM, while the Sony C1V-Series implements 100MHz SDRAM only. Compared to x86 standards, the processor core is relatively simple and consumes little space. Inside, the processor works with up to 4 very long instruction words (VLIW) per clock cycle. The VLIW engine has two integer units, one floating-point unit, one load/store unit and a branch unit. The VLIW native instructions are generated by Code Morphing software dynamically from the x86 instructions.
The Code Morphing software is loaded from the Flash BIOS into the RAM. Together with the translation cache it consumes 8-16MB of memory. Sony has implemented a 16MB version that reduces the 128MB onboard memory. A Crusoe 64/128bit VLIW is called a module and contains up to four RISC like instructions, called atoms. All atoms within a molecule are executed in parallel. The molecule format determinates how atoms get routed to the functional unit. Modern x86 processors from Intel or AMD have a similar way of translating and transforming x86 instructions, but these are implemented in very complex hardware that is fast, and they also consume a lot of chip real estate and power.
The Transmeta method has the benefit of software upgrades and lower costs. For notebook maker there are other important features available. An additional north bridge is not needed, and the off the shelf Intel 82371MB Southbridge can be implemented for IO and EIDE.