1989_MELPS_7700_Software_Manual

Direct Indirect Indexed V
Mode
Function
Direct indirect indexed Y addressing mode
The value obtained by adding the instruction's second byte and the contents of the
direct page register specifies 2 adjacent bytes in memory bank-O.
The value obtained by adding the contents of these bytes and the contents of the
index register Y specifies address of the actual data in memory bank-DT (DT is
contents of data bank register). If, however, the value obtained by adding the contents
of the instruction's second byte and the direct page register exceeds the bank­
Orange, the specified location will be in bank-1. Also, if addition of the contents of
memory and index register Y generate a carry, the bank number will be 1 larger than
the contents of the data bank register.
Instruction: ADC, AND, CMP, DIV, EaR, LOA, MPY, ORA, SBC, STA
ex.
: Mnemonic
ADC A, (1EH),Y
(m = 1, x = 1 )
Machine Code
71 16 1E 16
Memory
6ank-O
1252"
1253,.
DATAl (01,.)
DATA II (12,,)
}
Index
Register Y
+~=12E7,.
f----- --
c--------
I Direct Page
L Register
~+
Op Code (71,.)
Operand (1 E,,)
f--------
f---------
Data Bank
RegIster
A-A+C+I DATA I ~ DATA [E!J 12E7,. ~
.....
.,.;
21