Three Types of Translation

T oday’s most commercially significant microprocessors remain firmly wedded to legacy instruction set architectures, some of which are now over a decade old. Despite the admitted shortcomings of these ISAs, manufacturers are reluctant to develop radically new ones because they risk losing the commercial advantage of their product’s existing software base. On the other side of the coin, software developers find porting code to a new architecture difficult and time-consuming. If the architecture fails to gain enough market share, they—like the hardware developers— also risk losing a significant investment. Both these factors have at times conspired to forestall innovation in processor design. They also make it more difficult for new competitors to arise. Binary translation—a set of techniques that directly translate compiled code—could help break the innovation-strangling relation between ISAs and their software base.