80960KB
4
Figure 3. Instruction Formats
OpcodeDisplacement
OpcodeReg/LitRegMDisplacement
OpcodeRegReg/LitModesExt’d OpReg/Lit
OpcodeRegBaseMXOffset
OpcodeRegBaseModeScalexxOffset
Displacement
Control
Compare and
Branch
Register to
Register
Memory
Access—Short
Memory
Access—Long
1.1.1 Memory Space And Addressing Modes
The 80960KB offers a linear programming
environment so that all programs running on the
processor are contained in a single address space.
Maximum address space size is 4 Gigabytes (2
32
bytes).
For ease of use the 80960KB has a small number of
addressing modes, but includes all those necessary
to ensure efficient execution of high-level languages
such as C. Table 2 lists the modes.
1.1.2 Data Types
The 80960KB recognizes the following data types:
Numeric:
• 8-, 16-, 32- and 64-bit ordinals
• 8-, 16-, 32- and 64-bit integers
• 32-, 64- and 80-bit real numbers
Non-Numeric:
•Bit
• Bit Field
• Triple Word (96 bits)
• Quad-Word (128 bits)
1.1.3 Large Register Set
The 80960KB programming environment includes a
large number of registers. In fact, 32 registers are
available at any time. The availability of this many
registers greatly reduces the number of memory
accesses required to perform algorithms, which
leads to greater instruction processing speed.
There are two types of general-purpose registers:
local and global. The 20 global registers consist of
sixteen 32-bit registers (G0 though G15) and four
80-bit registers (FP0 through FP3). These registers
Table 2. Memory Addressing Modes
• 12-Bit Offset
• 32-Bit Offset
• Register-Indirect
• Register + 12-Bit Offset
• Register + 32-Bit Offset
• Register + (Index-Register x Scale-Factor)
• Register x Scale Factor + 32-Bit Displacement
• Register + (Index-Register x Scale-Factor) +
32-Bit Displacement
• Scale-Factor is 1, 2, 4, 8 or 16
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