Instruction manual

2
Memory and I/O Addressing
This chapter describes the DEC 3000 AXP systems’ address maps, the methods of
addressing I/O space, and system I/O registers.
Note
The addresses are 34-bit physical addresses, numbered in hexadecimal
notation.
In all register diagrams, an X in a bit position indicates that the contents
of the bit are ignored when written.
This chapter covers the following topics:
• Memory alignment (Section 2.1)
• Memory address spaces (Section 2.2)
• I/O address spaces (Section 2.3)
• TURBOchannel interface bit decode map for I/O addresses (Section 2.4)
• CPU registers (Section 2.5)
• Bcache tag space (Section 2.6)
Memory and I/O Addressing 2–1