Digital Photo Keychain User Manual

INSTRUCTION DESCRIPTIONS

A - 230 INSTRUCTION SET DETAILS MOTOROLA

Instruction Fields 1:

S1∗S2 Q Q Q Sign k D d

X0 X0 0 0 0 + 0 A 0

Y0 Y0 0 0 1 – 1 B 1

X1 X0 0 1 0

Y1 Y0 0 1 1

X0 Y1 1 0 0

Y0 X0 1 0 1

X1 Y0 1 1 0

Y1 X1 1 1 1

Note: Only the indicated S1

∗S2 combinations are valid. X1∗X1 and Y1∗Y1 are not valid.

Timing: 2+mv oscillator clock cycles

Memory: 1+mv program words

Example 2:

MPY X1, #9, A ;

Explanation of Example 2: The content of X1 is multiplied by 2

-9

and the result is

placed in the A accumulator. The net effect of this operation is to divide the content of

X1 by 2

and place the result in the accumulator. An alternate interpretation is that X1 is

right shifted 9 places and filled with the sign bit (0 for a positive number and 1 for a neg-

ative number) and then the result is placed in the accumulator.

MPY Signed Multiply

MPY

Before Execution After Execution

$654321

A A

$00:000000:000000 $00:0032A1:908000

$654321