Specifications

A–28 System Address Mapping
Subject to Change – 17 January 1997
21164 Address Space
The size field (address bits <38:37>) is added by the 21164 hardware as shown in the
following list. The software value is zero.
The following operations have single data transfers on the PCI:
•
INT1 read/write operations
•
INT2 read/write operations
•
INT4 read operations
The following operations may have multiple data transfers on the PCI:
•
INT4 write operations
•
INT8 read/write operations
Byte/word support is enabled when 21164 CSR ICSR<17>=1 and when CIA CSR
CIA_CNFG<IOA_BWEN>=1. Table A–9 shows noncached 21164 addresses when
byte/word support is enabled.
Size Data Size
00 INT8
01 INT4
10 INT2
11 INT1
Table A–9 21164 Byte/Word Addressing
Instruction addr<38:37> int4_valid<3:0>
LDQ 00 INT8 mask
LDL 01
addr<3:2>
,<1:0>undefined
LDWU 10
addr<3:1>
,<0>undefined
LDBU 11
addr<3:0>
STQ 00 INT4 mask
STL 01 INT4 mask
STW 10
addr<3:1>
,<0>undefined
STB 11
addr<3:0>