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RIW Field:
Direction of operand transfer is specified by this field. When the bit is set, the
transfer is from CPU to development system. When the bit is clear, data is
written to the CPU or to memory from the development system.
Operand Size:
For sized operations, this field specifies the operand data size. All addresses
are expressed as 32-bit absolute values.
The size field is encoded as
follows:
Encoding
Operand Size
00
Byte
01
Word
10
Long
11
Reserved
Address/Data (A/D) Field:
The A/D field is used by commands that operate on address and data
registers. It determines whether the register field specifies a data or address
register. One indicates an address register; zero, a data register. For other
commands, this field may be interpreted differently.
Register Field:
In most commands, this field specifies the register number when operating on
an address or data register.
Extension Words (as required):
At this time, no command requires an extension word to specify fully the
operation to be performed, but some commands require extension words for
.w
addresses or immediate data.
Addresses require two extension words _
because only absolute long addressing is permitted. Immediate data can be
either one or two words in length -
byte and word data each require a single
extension word, . long-word data requires two words.
Both operands and
addresses are transferred most significant word first.
7.2.8.2 Command Sequence Diagram
A command sequence diagram illustrates the serial bus traffic for each
command.
Each bubble in the diagram represents a single 17-bit transfer
CPU32 REFERENCE MANUAL
DEVELOPMENT SUPPORT
MOTOROLA
7-15
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