E.1.1 Powerpc Register Set—Uisa - Motorola MPC8240 User Manual

PowerPC Register Set
Conversely, some SPRs in the processor core may not be implemented at all or may not be
implemented in the same way in other PowerPC processors.
E.1.1 PowerPC Register Set—UISA
The PowerPC UISA registers, shown in Figure E-1, can be accessed by either user- or
supervisor-level instructions. The general-purpose registers (GPRs) and floating-point
registers (FPRs) are accessed through instruction operands. Access to registers can be
explicit (that is, through the use of specific instructions for that purpose such as the mtspr
and mfspr instructions) or implicit as part of the execution (or side effect) of an instruction.
Some registers are accessed both explicitly and implicitly.
The number to the right of the register name indicates the decimal number that is used in
the syntax of the instruction operands to access the register (for example, the number used
to access the XER is one).
E-2 MPC8240 Integrated Processor User's Manual