Instruction Set Architecture
Part of the interface between hardware and software that is visible to the programmer
Instruction Set
- RISC, CISC , VLIW-EPIC but also other issues such as how branches are handled, multimedia/graphics extensions etc.
Addressing modes (including how the PC is used)
Registers
- Integer, floating-point, but also flat vs.windows, and special-purpose registers, e.g. for multiply/divide or for condition codes or for predication