NonStop S-Series Server Description Manual (G06.24+)

TNS Instruction Set
HP NonStop S-Series Server Description Manual—520331-003
11-2
Memory Addressing Instructions
Memory Addressing Instructions
Figure 11-1 shows the instruction word format for memory data reference instructions
that refer to single-length (16-bit) operands. There are ten such instructions: LDX,
NSTO, LOAD, STOR, LDB, STB, LDD, STD, LADR, and ADM.
For both the single-length and doubleword formats, bit 7 begins the mode and
displacement field. The 9-bit field of I.<7:15> provides different displacement ranges
depending on the mode selected. Four of the modes are with reference to the data
segment, and the other (SG-relative) is with reference to the system data segment.
I.<5:6> is the indexing field, specifying either no indexing or a code that identifies one
of three stack registers that contains the index value. I.<0> is the direct/indirect
specifier.
Figure 11-1. Memory Addressing Instructions Provide Access to the Data
Segment
Index Value
Index Value
Index Value
567 150
Mode and Displacement
Mode
G-Relative
L-Plus-Relative
SG-Relative
L-Minus-Relative
S-Minus-Relative
0
0
10
10
11
11
1111
Displacement (0:255)
Displacement (0:127)
Displacement (0:63)
Displacement (0:31)
Displacement (0:31)
00
01
10
11
X
0
1
I
= Direct
= Indirect
= No Indexing
Register Stack
R [5]
R [6]
R [7]
Opcode
VST319.vsd