diff --git a/src/65c02isa.csv b/src/65c02isa.csv
index 2901bcc..eb55211 100644
--- a/src/65c02isa.csv
+++ b/src/65c02isa.csv
@@ -134,7 +134,7 @@ OP_NOPI_84,"nop",IMPLIED,1,NULL,false
 OP_STY_ZP,"sty",ZP,2,emul_sty,false
 OP_STA_ZP,"sta",ZP,2,emul_sta,false
 OP_STX_ZP,"stx",ZP,2,emul_stx,false
-OP_SMB0_ZP,"smb0",ZP,2,NULL,false
+OP_SMB0_ZP,"smb0",ZP,2,emul_smb0,false
 OP_DEY,"dey",IMPLIED,1,emul_dey,false
 OP_BIT_IMM,"bit",IMMEDIATE,2,emul_bit,false
 OP_TXA,"txa",IMPLIED,1,emul_txa,false
@@ -150,7 +150,7 @@ OP_NOPI_94,"nop",IMPLIED,1,NULL,false
 OP_STY_ZPX,"sty",ZPX,2,emul_sty,false
 OP_STA_ZPX,"sta",ZPX,2,emul_sta,false
 OP_STX_ZPY,"stx",ZPY,2,emul_stx,false
-OP_SMB1_ZP,"smb1",ZP,2,NULL,false
+OP_SMB1_ZP,"smb1",ZP,2,emul_smb1,false
 OP_TYA,"tya",IMPLIED,1,emul_tya,false
 OP_STA_ABSY,"sta",ABSOLUTEY,3,emul_sta,false
 OP_TXS,"txs",IMPLIED,1,emul_txs,false
@@ -166,7 +166,7 @@ OP_NOPI_A4,"nop",IMPLIED,1,NULL,false
 OP_LDY_ZP,"ldy",ZP,2,emul_ldy,false
 OP_LDA_ZP,"lda",ZP,2,emul_lda,false
 OP_LDX_ZP,"ldx",ZP,2,emul_ldx,false
-OP_SMB2_ZP,"smb2",ZP,2,NULL,false
+OP_SMB2_ZP,"smb2",ZP,2,emul_smb2,false
 OP_TAY,"tay",IMPLIED,1,emul_tay,false
 OP_LDA_IMM,"lda",IMMEDIATE,2,emul_lda,false
 OP_TAX,"tax",IMPLIED,1,emul_tax,false
@@ -182,7 +182,7 @@ OP_NOPI_B4,"nop",IMPLIED,1,NULL,false
 OP_LDY_ZPX,"ldy",ZPX,2,emul_ldy,false
 OP_LDA_ZPX,"lda",ZPX,2,emul_lda,false
 OP_LDX_ZPY,"ldx",ZPY,1,emul_ldx,false
-OP_SMB3_ZP,"smb3",ZP,2,NULL,false
+OP_SMB3_ZP,"smb3",ZP,2,emul_smb3,false
 OP_CLV,"clv",IMPLIED,1,emul_clv,false
 OP_LDA_ABSY,"lda",ABSOLUTEY,3,emul_lda,false
 OP_TSX,"tsx",IMPLIED,1,emul_tsx,false
@@ -198,7 +198,7 @@ OP_NOPI_C4,"nop",IMPLIED,1,NULL,false
 OP_CPY_ZP,"cpy",ZP,2,emul_cpy,false
 OP_CMP_ZP,"cmp",ZP,2,emul_cmp,false
 OP_DEC_ZP,"dec",ZP,2,emul_dec,false
-OP_SMB4_ZP,"smb4",ZP,2,NULL,false
+OP_SMB4_ZP,"smb4",ZP,2,emul_smb4,false
 OP_INY,"iny",IMPLIED,1,emul_iny,false
 OP_CMP_IMM,"cmp",IMMEDIATE,2,emul_cmp,false
 OP_DEX,"dex",IMPLIED,1,emul_dex,false
@@ -214,7 +214,7 @@ OP_NOPI_D4,"nop",IMPLIED,1,NULL,false
 OP_NOPI_D5,"nop",ZPX,2,NULL,false
 OP_CMP_ZPX,"cmp",ZPX,2,emul_cmp,false
 OP_DEC_ZPX,"dec",ZPX,2,emul_dec,false
-OP_SMB5_ZP,"smb5",ZP,2,NULL,false
+OP_SMB5_ZP,"smb5",ZP,2,emul_smb5,false
 OP_CLD,"cld",IMPLIED,1,NULL,false
 OP_CMP_ABSY,"cmp",ABSOLUTEY,3,emul_cmp,false
 OP_PHX,"phx",IMPLIED,1,emul_phx,false
@@ -230,7 +230,7 @@ OP_NOPI_E4,"nop",IMPLIED,1,NULL,false
 OP_CPX_ZP,"cpx",ZP,2,emul_cpx,false
 OP_SBC_ZP,"sbc",ZP,2,NULL,false
 OP_INC_ZP,"inc",ZP,2,emul_inc,false
-OP_SMB6_ZP,"smb6",ZP,2,NULL,false
+OP_SMB6_ZP,"smb6",ZP,2,emul_smb6,false
 OP_INX,"inx",IMPLIED,1,emul_inx,false
 OP_SBC_IMM,"sbc",IMMEDIATE,2,NULL,false
 OP_NOP,"nop",IMPLIED,1,emul_nop,false
@@ -246,7 +246,7 @@ OP_NOPI_F4,"nop",IMPLIED,1,NULL,false
 OP_NOPI_F5,"nop",ZPX,2,NULL,false
 OP_SBC_ZPX,"sbc",ZPX,2,NULL,false
 OP_INC_ZPX,"inc",ZPX,2,emul_inc,false
-OP_SMB7_ZP,"smb7",ZP,2,NULL,false
+OP_SMB7_ZP,"smb7",ZP,2,emul_smb7,false
 OP_SED,"sed",IMPLIED,1,NULL,false
 OP_SBC_ABSY,"sbc",ABSOLUTEY,3,NULL,false
 OP_PLX,"plx",IMPLIED,1,emul_plx,false
diff --git a/src/emulation.c b/src/emulation.c
index 415f4a6..9ff4d38 100644
--- a/src/emulation.c
+++ b/src/emulation.c
@@ -494,7 +494,7 @@ emul_rts(rk65c02emu_t *e, void *id, instruction_t *i)
 	e->regs.PC = retaddr;
 }
 
-/* RMBx - reset or set memory bit (handles RMB0-RMB7) */
+/* RMBx - reset memory bit (handles RMB0-RMB7) */
 void
 emul_rmb(rk65c02emu_t *e, void *id, instruction_t *i, uint8_t bit)
 {
@@ -632,6 +632,58 @@ emul_sei(rk65c02emu_t *e, void *id, instruction_t *i)
 	e->regs.P |= P_IRQ_DISABLE;
 }
 
+/* SMBx - set memory bit (handles SMB0-SMB7) */
+void
+emul_smb(rk65c02emu_t *e, void *id, instruction_t *i, uint8_t bit)
+{
+	uint8_t val;
+
+	val = instruction_data_read_1(e, (instrdef_t *) id, i);
+
+	val |= (1 << bit);
+
+	instruction_data_write_1(e, id, i, val);
+}
+void
+emul_smb0(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 0);
+void
+emul_smb1(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 1);
+}
+void
+emul_smb2(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 2);
+}
+void
+emul_smb3(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 3);
+}
+void
+emul_smb4(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 4);
+}
+void
+emul_smb5(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 5);
+}
+void
+emul_smb6(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 6);
+}
+void
+emul_smb7(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	emul_smb(e, id, i, 7);
+}
+
 /* STP - stop the processor */
 void
 emul_stp(rk65c02emu_t *e, void *id, instruction_t *i)