108Section 10: The Index Register and Loop Control

Indirect Addressing

If RI contains:

%will address:

tVor GVwill

 

transfer to:*

 

 

 

 

 

 

21

R21

´bB

22

R22

"

"

C

23

R23

"

"

Á

24

R24

"

"

E

 

 

65

R65

 

 

*For RI 0 only.

Index Register Arithmetic

Direct. O or l { + , -, *, ÷ } V. Storage or recall arithmetic operates with the Index register in the same manner as upon other data storage registers (page 43).

Indirect. Oor l{ +, -, *, ÷} %carries out storage or recall arithmetic with the contents of the data storage register addressed by the integer portion of the number (0 to 65) in the Index register. See the above table.

Exchanging the X-Register

Direct. ´ X V exchanges contents between the X-register and the Index register. (Works the same as Xn does with registers 0 through .9.)

Indirect. ´X%exchanges contents between the X-register and the data storage register addressed by the number (0 to 65) in the Index register. See the above table.

Indirect Branching With V

The V key—but not the % key—can be used for indirect branching (tV) and subroutine calls (GV). (Only the integer portion of the number in RI is used.) (% is only used for indirect addressing of storage registers).