IX and IY registers

Table of Contents

If an opcode works with the Registers HL, H or L then if that opcode is prefixed by 0xDD then it will also work on the appropriate IX, IX_h or IX_l registers, with some exceptions.

The 0xFD prefix would also work but for the IY, IY_h or IY_l registers

The exceptions are instructions like LD H,IX_h or LD L,IY_h where it isn't clear from the opcode which register the 0xFD or 0xDD prefix should operate against.

1 - LD IX undocumented instructions

Undocumented instructions for LD IX

Opcode Matrix

	A	B	C	D	E	n	IXh	IXl
A							LD A,IXh DD7C	LD A,IXl DD7D
B							LD B,IXh DD44	LD B,IXl DD45
C							LD C,IXh DD4C	LD C,IXl DD4D
D							LD D,IXh DD54	LD D,IXl DD55
E							LD E,IXh DD5C	LD E,IXl DD5D
IXh	LD IXh,A DD67	LD IXh,B DD60	LD IXh,C DD61	LD IXh,D DD62	LD IXh,E DD63	LD IXh,n DD26nn	LD IXh,IHh DD64	LD IXh,IHl DD65
IXl	LD IXl,A DD6F	LD IXl,B DD68	LD IXl,C DD69	LD IXl,D DD6A	LD IXl,E DD6B	LD IXl,n DD2Enn	LD IXl,IHh DD6C	LD IXl,IHl DD6D

Opcode Matrix Legend
Instruction Opcode hex		Undocumented

2 - LD IY undocumented instructions

Undocumented instructions for LD IY

Opcode Matrix

	A	B	C	D	E	n	IYh	IYl
A							LD A,IYh FD7C	LD A,IYl FD7D
B							LD B,IYh FD44	LD B,IYl FD45
C							LD C,IYh FD4C	LD C,IYl FD4D
D							LD D,IYh FD54	LD D,IYl FD55
E							LD E,IYh FD5C	LD E,IYl FD5D
IYh	LD IYh,A FD67	LD IYh,B FD60	LD IYh,C FD61	LD IYh,D FD62	LD IYh,E FD63	LD IYh,n FD26nn	LD IYh,IHh FD64	LD IYh,IHl FD65
IYl	LD IYl,A FD6F	LD IYl,B FD68	LD IYl,C FD69	LD IYl,D FD6A	LD IYl,E FD6B	LD IYl,n FD2Enn	LD IYl,IHh FD6C	LD IYl,IHl FD6D

Opcode Matrix Legend
Instruction Opcode hex		Undocumented

3 - Undocumented Math instructions with the IX register

Undocumented math instructions for IX register

Opcode Matrix

	INC	DEC	ADD A	ADC A	SUB	SBC A	AND	XOR	OR	CP
IXh	INC IXh DD24	DEC IXh DD25	ADD A,IXh DD84	ADC A,IXh DD8C	SUB IXh DD94	SBC A,IXh DD9C	AND IXh DDA4	XOR IXh DDAC	OR IXh DDB4	CP IXh DDBC
IXl	INC IXl DD2C	DEC IXl DD2D	ADD A,IXl DD85	ADC A,IXl DD8D	SUB IXl DD95	SBC A,IXl DD9D	AND IXl DDA5	XOR IXl DDAD	OR IXl DDB5	CP IXl DDBD

Opcode Matrix Legend
Instruction Opcode hex		Undocumented

4 - Undocumented Math instructions with the IY register

Undocumented math instructions for IY register

Opcode Matrix

	INC	DEC	ADD A	ADC A	SUB	SBC A	AND	XOR	OR	CP
IYh	INC IYh FD24	DEC IYh FD25	ADD A,IYh FD84	ADC A,IYh FD8C	SUB IYh FD94	SBC A,IYh FD9C	AND IYh FDA4	XOR IYh FDAC	OR IYh FDB4	CP IYh FDBC
IYl	INC IYl FD2C	DEC IYl FD2D	ADD A,IYl FD85	ADC A,IYl FD8D	SUB IYl FD95	SBC A,IYl FD9D	AND IYl FDA5	XOR IYl FDAD	OR IYl FDB5	CP IYl FDBD

Opcode Matrix Legend
Instruction Opcode hex		Undocumented