User`s guide

DWMBB Adapter
The steps used for the 40-bit address translation using the 4-Kbyte page
sizes are as follows:
1 Check the upper address bits: VAXBI A<29:28> must be zero.
2 Access PMR for PMRE: VAXBI A<27:12> is an index into the PMR to
fetch the PMRE.
3 Check PMRE valid bit: If PMRE<31> = 1, then PFN is valid; otherwise
PFN is invalid and the transaction is aborted.
4 ECC check: If no uncorrectable error, then PFN is good; otherwise
PFN is bad and the transaction is aborted.
5 Generate XMI address: Zero XMI A<39>; PMRE<26:0> XMI
A<38:12>; VAXBI A<11:0> XMI A<11:0>.
Figure 3–5 shows the 40-bit address translation using 4-Kbyte page sizes.
Figure 3–5 40-Bit Addressing Mode with 4-Kbyte Page Size
3
1
3
0
2
9
2
8
2
7
1
2
1
10
VAXBI A<31:0> 0 PMR INDEX ADDRESS PAGE OFFSET
Access PMR for PMRE
3
1
3
0
2
9
2
7
2
6 0
PMRE PFN
XMI
A<39:0>
Bit <39> (the I/O select) is always forced to 0
msb−p086−89
LEN
XMI PHYSICAL ADDRESS
1
2
1
10
V0
Check if PFN is valid
Unused
3
9
3
8
0
3–12