
MOTOROLA
Chapter 1. Overview
1-21
The machine status save/restore register 1 (SRR1) is a 32-bit register used to save
machine status on exceptions and to restore machine status when an
rfi
instruction
is executed.
The 32-bit SPRG0–SPRG3 registers are provided for operating system use.
The external access register (EAR) is a 32-bit register that controls access to the
external control facility through the External Control In Word Indexed (
eciwx
) and
External Control Out Word Indexed (
ecowx
) instructions.
The time base register (TB) is a 64-bit register that maintains the time of day and
operates interval timers. The TB consists of two 32-bit fields—time base upper
(TBU) and time base lower (TBL).
The processor version register (PVR) is a 32-bit, read-only register that identifies the
version (model) and revision level of the PowerPC processor.
Block address translation (BAT) arrays—The PowerPC architecture defines 16 BAT
registers, divided into four pairs of data BATs (DBATs) and four pairs of instruction
BATs (IBATs). See Figure 2-1 for a list of the SPR numbers for the BAT arrays.
The following supervisor-level SPRs are implementation-specific to the 603e:
The DMISS and IMISS registers are read-only registers that are loaded
automatically upon an instruction or data TLB miss.
The HASH1 and HASH2 registers contain the physical addresses of the primary and
secondary page table entry groups (PTEGs).
The ICMP and DCMP registers contain a duplicate of the first word in the page table
entry (PTE) for which the table search is looking.
The required physical address (RPA) register is loaded by the processor with the
second word of the correct PTE during a page table search.
The hardware implementation (HID0 and HID1) registers provide the means for
enabling the 603e’s checkstops and features, and allows software to read the
configuration of the PLL configuration signals.
The instruction address breakpoint register (IABR) is loaded with an instruction
address that is compared to instruction addresses in the dispatch queue. When an
address match occurs, an instruction address breakpoint exception is generated.
Figure 2-1 shows all the 603e registers available at the user and supervisor level. The
numbers to the right of the SPRs indicate the number that is used in the syntax of the
instruction operands to access the register.