
MOTOROLA
Chapter 1. Overview
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1.3.1.3 Run_N Counter Register (Run_N)
The 33-bit Run_N counter register is unique to the PID7v-603e. The Run_N counter is used
by the COP to control the number of processor cycles that the processor runs before halting.
The most-significant 32 bits form a 32-bit counter. The function of the least-significant bit
remains unchanged.
1.3.1.4 General-Purpose Registers (GPRs)
The PowerPC architecture defines 32 user-level, general-purpose registers (GPRs). These
registers are either 32 bits wide in 32-bit PowerPC microprocessors and 64 bits wide in
64-bit PowerPC microprocessors. The GPRs serve as the data source or destination for all
integer instructions.
1.3.1.5 Floating-Point Registers (FPRs)
The PowerPC architecture also defines 32 user-level, 64-bit floating-point registers (FPRs)
(not supported by the EC603e microprocessor). The FPRs serve as the data source or
destination for floating-point instructions. These registers can contain data objects of either
single- or double-precision floating-point formats.
1.3.1.6 Condition Register (CR)
The CR is a 32-bit user-level register that consists of eight four-bit fields that reflect the
results of certain operations, such as move, integer and floating-point compare, arithmetic,
and logical instructions, and provide a mechanism for testing and branching.
1.3.1.7 Floating-Point Status and Control Register (FPSCR)
The floating-point status and control register (FPSCR) is a user-level register that contains
all exception signal bits, exception summary bits, exception enable bits, and rounding
control bits needed for compliance with the IEEE 754 standard. (Note that this is not
supported by the EC603e microprocessor.)
1.3.1.8 Machine State Register (MSR)
The machine state register (MSR) is a supervisor-level register that defines the state of the
processor. The contents of this register are saved when an exception is taken and restored
when the exception handling completes. The 603e implements the MSR as a 32-bit register;
64-bit PowerPC processors implement a 64-bit MSR. To ensure proper operation of the
EC603e microprocessor, the MSR[FP] bit should remain cleared to zero.
1.3.1.9 Segment Registers (SRs)
For memory management, 32-bit PowerPC microprocessors implement sixteen 32-bit
segment registers (SRs). To speed access, the 603e implements the segment registers as two
arrays; a main array (for data memory accesses) and a shadow array (for instruction
memory accesses). Loading a segment entry with the Move to Segment Register
(
mtsr
)
instruction loads both arrays.