LTD
Load TREG, Accumulate Previous Product, and Move Data
7-96
Words
1
Cycles for a Single LTD Instruction
Program
Operand
ROM
DARAM
SARAM
External
‡
DARAM
1
1
1
1+p
SARAM
1
1
1, 3
†
1+p
External
2+2d
2+2d
2+2d
5+2d+p
† If the operand and the code are in the same SARAM block
‡ If the LTD instruction is used with external memory, the data move will not occur. (The previous
product will be accumulated, and the TREG will be loaded.)
Cycles for a Repeat (RPT) Execution of an LTD Instruction
Program
Operand
ROM
DARAM
SARAM
External
‡
DARAM
n
n
n
n+p
SARAM
2n–2
2n–2
2n–2, 2n+1
†
2n–2+p
External
4n–2+2nd
4n–2+2nd
4n–2+2nd
4n+1+2nd+p
† If the operand and the code are in the same SARAM block
‡ If the LTD instruction is used with external memory, the data move will not occur. (The previous
product will be accumulated, and the TREG will be loaded.)
Example 1
LTD
126
;(DP = 7: addresses 0380h–03FFh,
;PM = 0: no shift of product).
Before Instruction
After Instruction
Data Memory
Data Memory
3FEh
62h
3FEh
62h
Data Memory
Data Memory
3FFh
0h
3FFh
62h
TREG
3h
TREG
62h
PREG
0Fh
PREG
0Fh
ACC
X
5h
ACC
0
14h
C
C
Cycles