INSTRUCTION DESCRIPTIONS
A - 288 INSTRUCTION SET DETAILS MOTOROLA
Operation: Assembler Syntax:
S➞D (parallel move) TFR S,D (parallel move)
Description: Transfer data from the specified source data ALU register S to the speci-
fied destination data ALU accumulator D. TFR uses the internal data ALU data paths;
thus, data does not pass through the data shifter/limiters. This allows the full 56-bit con-
tents of one of the accumulators to be transferred into the other accumulator without
data shifting and/or limiting. Moreover, since TFR uses the internal data ALU data paths,
parallel moves are possible. The TFR instruction only affects the L condition code bit
which can be set by data limiting associated with the instruction’s parallel move opera-
tions.
Example: :
TFR A,B A,X1 Y:(R4+N4),Y0 ;move A to B and X1, update Y0
:
Explanation of Example: Prior to execution, the 56-bit A accumulator contains the
value $01:234567:89ABCD, and the 56-bit B accumulator contains the value
$ff:FFFFFF:FFFFFF. The execution of the TFR A,B instruction moves the 56-bit value in
the A accumulator into the 56-bit B accumulator using the internal data ALU data paths
without any data shifting and/or limiting. The value in the B accumulator would have
been limited if a MOVE A,B instruction had been used. Note, however, that the parallel
move portion of the TFR instruction does use the data shifter/limiters. Thus, the value
stored in the 24-bit X1 register (not shown) would have been limited in this example.
This example illustrates a triple move instruction.
TFR Transfer Data ALU Register TFR
Before Execution After Execution
A$01:234567:89ABCD
B B
$FF:FFFFFF:FFFFFF $01:234567:89ABCD
$01:234567:89ABCD
A