The
Crusoe processor solutions consist of a hardware engine logically surrounded by
a software layer. The engine is a very long instruction word (VLIW) CPU capable
of executing up to four operations in each clock cycle. The VLIW's native instruction
set bears no resemblance to the x86 instruction set; it has been designed purely
for fast low power implementation using conventional CMOS fabrication. The surrounding
software layer gives x86 programs the impression that they are running on x86
hardware. The software layer is called Code Morphing software because it dynamically
"morphs" x86 instructions into VLIW instructions. The Code Morphing
software includes a number of advanced features to achieve good system-level performance.
Code Morphing support facilities are also built into the underlying CPUs. In other
words, the Transmeta designers have judiciously rendered some functions in hardware
and some in software, according to the product design goals and constraints. Transmeta's
Code Morphing technology changes the entire approach to designing microprocessors.
By demonstrating that practical microprocessors can be implemented as hardware-software
hybrids, Transmeta has dramatically expanded the design space that microprocessor
designers can explore for optimum solutions. Upgrades to the software portion
of a microprocessor can be rolled out independently from the chip. Finally, decoupling
the hardware design from the system and application software that use it frees
hardware designers to evolve and eventually replace their designs without perturbing
legacy software.
The concept of Crusoe is well understood from the simple sketch
of the proceesor architecture , called 'amoeba'.In this concept , the x86 architecture
is an ill-defined amoeba containing features like segmentation, ASCII arithmetic
,variable-length instructions etc. The amoeba explained how a traditional microprocessor
was, in their design, to be divided up into hardware and software.Thus Crusoe
was conceptualised as a hybrid microprocessor , that is it has a software part
and a hardware part with the software layer surrounding the hardware unit.The
role of software is to act as an emulator to translate x86 binaries into native
code at run time. Crusoe is a 128-bit microprocessor fabricated using the CMOS
process.The chip's design is based on a technique called VLIW to ensure design
simplicity and high performance.Besides this it also uses Transmeta's two pateneted
technologies , namely , Code Morphing Software and LongRun Power Management.It
is a highly integrated processor available in different vesions for different
market segments.
