November 09, 2018
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3.5.11 Direct Indexed with X-d,x
With Direct Indexed with X (d,x) addressing the second byte of the instruction is added to the sum of the
Direct Register and the X Index Register to form the 16-bit effective address. The operand is always in
Bank 0.
Instruction:
Opcode
offset
Direct Register
+
offset
direct address
+
X Reg
Operand
Address:
00
effective address
3.5.12 Direct Indexed with Y-d,y
With Direct Indexed with Y (d,y) addressing the second byte of the instruction is added to the sum of the
Direct Register and the Y Index Register to form the 16-bit effective address. The operand is always in
Bank 0.
Instruction:
Opcode
offset
Direct Register
+
offset
direct address
+
Y Reg
Operand
Address:
00
effective address
3.5.13 Direct Indirect Indexed-(d),y
Direct Indirect Indexed ((d),y) addressing is often referred to as Indirect Y addressing. The second byte
of the instruction is added to the Direct Register (D). The 16-bit content of this memory location is then
combined with the Data Bank register to form a 24-bit base address. The Y Index Register is added to
the base address to form the effective address.
Instruction:
Opcode
offset
Direct Register
+
offset
00
(direct address)
then: +
DBR
base address
+
Y Reg
Operand
Address:
effective address