diff --git a/cpu.c b/cpu.c
index 87d68c8..8eaeff1 100644
--- a/cpu.c
+++ b/cpu.c
@@ -34,7 +34,6 @@ struct registers {
 struct registers regs;
 
 enum addressing_mode {
-	AM_ACC,
 	AM_IMM,
 	AM_ZP,
 	AM_ZP_X,
@@ -199,7 +198,7 @@ and(uint8_t arg)
 }
 
 static void
-asl(uint8_t arg)
+asl_acc(void)
 {
 	uint16_t tmp;
 
@@ -211,6 +210,19 @@ asl(uint8_t arg)
 	STATUS_UPDATE_NEGATIVE(regs.a);
 }
 
+static void
+asl(uint16_t mem)
+{
+	uint16_t tmp;
+
+	tmp = peek(mem) << 1;
+	memwrite(mem, tmp & 0xFF);
+
+	regs.status.carry = tmp > 0xFF;
+	STATUS_UPDATE_ZERO(tmp);
+	STATUS_UPDATE_NEGATIVE(tmp);
+}
+
 static void
 bcc(uint8_t arg)
 {
@@ -398,7 +410,7 @@ inx(void)
 }
 
 static void
-iny(uint8_t arg)
+iny(void)
 {
 	regs.y++;
 
@@ -454,7 +466,7 @@ ldy(uint8_t arg)
 }
 
 static void
-lsr(uint8_t arg)
+lsr_acc(void)
 {
 	regs.status.carry = regs.a & 1;	// bit 0 in carry
 	regs.a >>= 1;
@@ -465,7 +477,24 @@ lsr(uint8_t arg)
 }
 
 static void
-nop(uint8_t arg)
+lsr(uint16_t mem)
+{
+	uint8_t tmp;
+
+	tmp = peek(mem);
+
+	regs.status.carry = tmp & 1;	// bit 0 in carry
+	tmp >>= 1;
+	tmp &= ~(1 << 7);		// bit 7 cleared
+
+	memwrite(mem, tmp);
+
+	STATUS_UPDATE_ZERO(tmp);
+	STATUS_UPDATE_NEGATIVE(tmp);
+}
+
+static void
+nop(void)
 {
 	return;
 }
@@ -525,35 +554,63 @@ plp(void)
 }
 
 static void
-rol(uint8_t arg)
+rol_acc(void)
 {
-	uint8_t tmp;
-	tmp = (regs.a & (1 << 7)) > 0;
+	uint8_t carry;
+	carry = (regs.a & (1 << 7)) > 0;
 
 	regs.a <<= 1;
 	regs.a |= regs.status.carry;
 
-	regs.status.carry = tmp;
+	regs.status.carry = carry;
 	STATUS_UPDATE_ZERO(regs.a);
 	STATUS_UPDATE_NEGATIVE(regs.a);
 }
 
 static void
-ror(uint8_t arg)
+rol(uint16_t mem)
 {
-	uint8_t tmp;
-	tmp = regs.a & 1;
+	uint8_t carry, tmp;
+	carry = (peek(mem) & (1 << 7)) > 0;
+
+	tmp = (peek(mem) << 1) | regs.status.carry;
+	memwrite(mem, tmp);
+
+	regs.status.carry = carry;
+	STATUS_UPDATE_ZERO(tmp);
+	STATUS_UPDATE_NEGATIVE(tmp);
+}
+
+static void
+ror_acc(void)
+{
+	uint8_t carry;
+	carry = regs.a & 1;
 
 	regs.a >>= 1;
 	regs.a |= regs.status.carry << 7;
 
-	regs.status.carry = tmp;
+	regs.status.carry = carry;
 	STATUS_UPDATE_ZERO(regs.a);
 	STATUS_UPDATE_NEGATIVE(regs.a);
 }
 
 static void
-rti(uint8_t arg)
+ror(uint16_t mem)
+{
+	uint8_t carry, tmp;
+	carry = peek(mem) & 1;
+
+	tmp = (peek(mem) >> 1) | (regs.status.carry << 7);
+	memwrite(mem, tmp);
+
+	regs.status.carry = carry;
+	STATUS_UPDATE_ZERO(tmp);
+	STATUS_UPDATE_NEGATIVE(tmp);
+}
+
+static void
+rti(void)
 {
 	plp();
 	regs.pc = PULL();
@@ -743,7 +800,7 @@ interpret(void)
 			cycles += 5;
 			break;
 		case 0x0a:
-			asl(opcode_arg(AM_ACC));
+			asl_acc();
 			cycles += 2;
 			break;
 		case 0x06:
@@ -954,10 +1011,6 @@ interpret(void)
 			eor(opcode_arg(AM_IND_Y));
 			cycles += 5;
 			break;
-		case 0x1a:
-			inc(opcode_arg(AM_ACC));
-			cycles += 2;
-			break;
 		case 0xe6:
 			inc(opcode_arg(AM_ZP));
 			cycles += 5;
@@ -979,7 +1032,7 @@ interpret(void)
 			cycles += 2;
 			break;
 		case 0xc8:
-			iny(opcode_arg(AM_ACC));
+			iny();
 			cycles += 2;
 			break;
 		case 0x4c:
@@ -1075,7 +1128,7 @@ interpret(void)
 			cycles += 4;
 			break;
 		case 0x4a:
-			lsr(opcode_arg(AM_ACC));
+			lsr_acc();
 			cycles += 2;
 			break;
 		case 0x46:
@@ -1095,7 +1148,7 @@ interpret(void)
 			cycles += 6;
 			break;
 		case 0xea:
-			nop(opcode_arg(AM_ACC));
+			nop();
 			cycles += 2;
 			break;
 		case 0x09:
@@ -1151,7 +1204,7 @@ interpret(void)
 			cycles += 4;
 			break;
 		case 0x2a:
-			rol(opcode_arg(AM_ACC));
+			rol_acc();
 			cycles += 2;
 			break;
 		case 0x26:
@@ -1171,7 +1224,7 @@ interpret(void)
 			cycles += 6;
 			break;
 		case 0x6a:
-			ror(opcode_arg(AM_ACC));
+			ror_acc();
 			cycles += 2;
 			break;
 		case 0x66:
@@ -1191,7 +1244,7 @@ interpret(void)
 			cycles += 6;
 			break;
 		case 0x40:
-			rti(opcode_arg(AM_ACC));
+			rti();
 			cycles += 6;
 			break;
 		case 0x60: