Virtual Machines

Chapter Seven Codesigned Virtual Machines

Both hardware and software have undergone radical changes since the first commercially available computers appeared in the early 1950s. In contrast, the basic character of the interface between hardware and software has been virtually unchanged during that time. Consequently, the instruction set architectures (ISAs) currently in use reflect a perspective and a division of labor between hardware and software that is decades old. At a time when hardware resources were very expensive and hardware was relatively simple, it made sense for the ISA to be a direct reflection of the specific hardware implementation. If the hardware had an accumulator, then the ISA had an accumulator. Over the years, however, ...