Freescale Semiconductor, Inc.
Besides the operation code, which specifies the function to be performed, an instruction
defines the location of every operand for the function. Instructions specify an operand
location in one of three ways:
• Register Specification
• Effective Address
• Implicit Reference
A register field of the instruction contains the number of
the register.
An effective address field of the instruction contains
address mode information.
The definition of an instruction implies the use of
specific registers.
The register field within an instruction specifies the register to be used. Other fields within
the instruction specify whether the register is an address or data register and how it is to
be used. The M68000PM/AD, M68000 Family Programmer’s Reference Manual, contains
detailed register information.
Except where noted, the following notation is used in this section:
Data
Immediate data from an instruction
Destination Destination contents
Source
Vector
An
Ax, Ay
Dn
Source contents
Location of exception vector
Any address register (A7–A0)
Address registers used in computation
Any data register (D7–D0)
Rc
Rn
Control register (VBR, SFC, DFC)
Any address or data register
Data registers, high- and low-order 32 bits of product
Data registers, division remainder, division quotient
Data registers, used in computation
Data registers, table interpolation values
Index register
Dh, Dl
Dr, Dq
Dx, Dy
Dym, Dyn
Xn
[An]
Address extension
cc
Condition code
d
Displacement
#
Example: d is a 16-bit displacement
16
ea
Effective address
# data
label
list
Immediate data; a literal integer
Assembly program label
List of registers
Example: D3–D0
[...]
Bits of an operand
Examples: [7] is bit 7; [31:24] are bits 31–24
MOTOROLA
MC68340 USER’S MANUAL
5- 13
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