PA-RISC to IA-64: transparent execution, no recompilation

Making the transition to a new architecture is never easy. Users want to keep running their favorite applications as they normally would, without stopping to adapt them to a different platform. For some legacy applications the problem is more severe. Without all the source code, it is well-nigh impossible to recompile the application to a new platform. Binary translation helps this transition process because it automatically converts the binary code from one instruction set to another without the need for high-level source code. However, different choices force different trade-offs between some form of interpretation (or emulation) and static translation. Interpretation requires no user intervention, but its performance is slow. Static translation, on the other hand, requires user intervention but provides much better performance. To help PA-RISC (precision architecture-reduced instruction set computing) users migrate to its upcoming IA-64 systems, Hewlett-Packard has developed the Aries software emulator, combining fast interpretation. The article describes how the system works and outlines its performance characteristics and quality.