System Address Mapping; Cpu Address Mapping To Pci Space - DEC Digital Alpha VME 4/224 User Manual

This chapter describes the mapping of the 34-bit processor physical address space
into memory and I/O space addresses. It also includes the translations of the
processor-initiated address into a PCI address, and PCI-initiated addresses into
physical memory addresses.

5.1 CPU Address Mapping to PCI Space

The 34-bit physical system bus (sysBus) address space is composed of the
following:
• Memory address space
• Local I/O space, for registers residing on the system bus (that is, registers in
the 21071-CA and 21071-DA chips)
• PCI space
The system bus represents the 21064A pin bus as well as control signals
between the 21071-CA and 21071-DA chips.
The PCI defines three physical address spaces:
• PCI memory space (for memory residing on the PCI)
• PCI I/O space
• PCI configuration space
In addition to these address spaces, the system bus I/O space is also used to
generate PCI interrupt acknowledge cycles and PCI special cycles. Figure 5–1
shows the address space. Table 5–1 provides a summary description of the
spaces.

System Address Mapping

Note
5
System Address Mapping 5–1