Specifications

A–20 System Address Mapping
Subject to Change – 17 January 1997
21164 Address Space
The ISA devices have reserved the lower 64KB of PCI I/O space (85.8000.0000 to
85.801F.FFFF). Hence, all PCI devices should be relocated above this region.
Note:
A quadword access to the PCI sparse I/O space will result in a 2-long-
word burst on the PCI. However, PCI devices might not support bursting
in I/O space.
1
Missing entries (such as word size with
addr<6:5>
= 11
2
cause UNPREDICTABLE results.
2
Byte enable set to zero indicates that the byte lane carries meaningful data.
Table A–5 PCI I/O Sparse Space Read/Write Encodings
Size Byte Offset 21164 PCI
Data-In
Register
addr<4:3> addr<6:5>
1
Instruction ad<2:0>
1
Byte
2
Enable
Byte Lanes
[7:0]
Byte
00
00
01
10
11
LDL, STL addr<7>,00
addr<7>,01
addr<7>,10
addr<7>,11
1110
1101
1011
0111
<0>
<1>
<2>
<3>
Word
01
00
01
10
LDL, STL addr<7>,00
addr<7>,01
addr<7>,10
1100
1001
0011
<1:0>
<2:1>
<3:2>
Tribyte
10
00
01
LDL, STL addr<7>,00
addr<7>,01
1000
0001
<2:0>
<3:1>
Longword
11
00 LDL, STL addr<7>,00 0000 <3:0>
Quadword
11
11 LDQ, STQ 000 0000 <7:0>