User`s guide

The XMI
2.2 XMI Addressing
The XMI supports one terabyte (2
40
bytes) of address space. The
VAX 6000 series systems use a maximum of (2
32
bytes). These
systems use one of three addressing modes:
• 30-bit mode used by VAX 6000 Models 200 through 500
• 32-bit mode used by VAX 6000 models above 500
• 30-bit mode in a 32-bit environment used by VAX 6000 models
above 500
Figure 2–3 shows how memory and I/O space are divided in the
30-bit and the 32-bit modes.
Figure 2–3 XMI Memory and I/O Address Space
30−BIT
BYTE ADDRESS
32−BIT
BYTE ADDRESS
0000 0000 Physical Mem Physical 0000
Space Memory
(512 Mbytes) Space
I/O Space
/
/
/
/
(3.5 Gbytes)
Space
0000
1FFF FFFF
0000
I/O 0000
(512 Mbytes)
msb−p390−91
(512 Mbytes)
DFFF FFFF
2000
E000
3FFF FFFF
EFFF FFFF
When a VAX 6000 system is in 30-bit mode, the 3 Gbytes of memory space
between address 2000 0000 (hex) and DFFF FFFF are not accessible.
Addressing these locations result in a machine check or hard error
interrupt.
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