diff --git a/src/65c02isa.csv b/src/65c02isa.csv
index fd3f4df..a6b221f 100644
--- a/src/65c02isa.csv
+++ b/src/65c02isa.csv
@@ -25,7 +25,7 @@ OP_ASL_ZPX,"asl",ZPX,2,NULL
 OP_RMB1_ZP,"rmb1",ZP,1,NULL
 OP_CLC,"clc",IMPLIED,1,emul_clc
 OP_ORA_ABSY,"ora",ABSOLUTEY,3,emul_ora
-OP_INC,"inc",ACCUMULATOR,1,NULL
+OP_INC,"inc",ACCUMULATOR,1,emul_inc
 OP_NOPI_1C,"nop",IMPLIED,1,NULL
 OP_TRB_ABS,"trb",ABSOLUTE,3,NULL
 OP_ORA_ABSX,"ora",ABSOLUTEX,3,emul_ora
@@ -57,7 +57,7 @@ OP_ROL_ZPX,"rol",ZPX,2,emul_rol
 OP_RMB3_ZP,"rmb3",ZP,2,NULL
 OP_SEC,"sec",IMPLIED,1,emul_sec
 OP_AND_ABSY,"and",ABSOLUTEY,3,emul_and
-OP_DEC,"dec",ACCUMULATOR,1,NULL
+OP_DEC,"dec",ACCUMULATOR,1,emul_dec
 OP_NOPI_3C,"nop",IMPLIED,1,NULL
 OP_BIT_ABSX,"bit",ABSOLUTEX,3,emul_bit
 OP_AND_ABSX,"and",ABSOLUTEX,3,emul_and
@@ -197,7 +197,7 @@ OP_NOPI_C3,"nop",IMMEDIATE,2,NULL
 OP_NOPI_C4,"nop",IMPLIED,1,NULL
 OP_CPY_ZP,"cpy",ZP,2,NULL
 OP_CMP_ZP,"cmp",ZP,2,NULL
-OP_DEC_ZP,"dec",ZP,2,NULL
+OP_DEC_ZP,"dec",ZP,2,emul_dec
 OP_SMB4_ZP,"smb4",ZP,2,NULL
 OP_INY,"iny",IMPLIED,1,emul_iny
 OP_CMP_IMM,"cmp",IMMEDIATE,2,NULL
@@ -205,7 +205,7 @@ OP_DEX,"dex",IMPLIED,1,emul_dex
 OP_WAI,"wai",IMPLIED,1,NULL
 OP_CPY_ABS,"cpy",ABSOLUTE,3,NULL
 OP_CMP_ABS,"cmp",ABSOLUTE,3,NULL
-OP_DEC_ABS,"dec",ABSOLUTE,3,NULL
+OP_DEC_ABS,"dec",ABSOLUTE,3,emul_dec
 OP_BBS4_REL,"bbs4",ZPR,2,NULL
 OP_BNE_REL,"bne",RELATIVE,2,NULL
 OP_CMP_IZPY,"cmp",IZPY,2,NULL
@@ -213,7 +213,7 @@ OP_CMP_IZP,"cmp",IZP,2,NULL
 OP_NOPI_D4,"nop",IMPLIED,1,NULL
 OP_NOPI_D5,"nop",ZPX,2,NULL
 OP_CMP_ZPX,"cmp",ZPX,2,NULL
-OP_DEC_ZPX,"dec",ZPX,2,NULL
+OP_DEC_ZPX,"dec",ZPX,2,emul_dec
 OP_SMB5_ZP,"smb5",ZP,2,NULL
 OP_CLD,"cld",IMPLIED,1,NULL
 OP_CMP_ABSY,"cmp",ABSOLUTEY,3,NULL
@@ -221,7 +221,7 @@ OP_PHX,"phx",IMPLIED,1,emul_phx
 OP_STP,"stp",IMPLIED,1,emul_stp
 OP_NOPI_DD,"nop",ABSOLUTE,3,NULL
 OP_CMP_ABSX,"cmp",ABSOLUTEX,3,NULL
-OP_DEC_ABSX,"dec",ABSOLUTEX,3,NULL
+OP_DEC_ABSX,"dec",ABSOLUTEX,3,emul_dec
 OP_BBS5_REL,"bbs5",ZPR,2,NULL
 OP_CPX_IMM,"cpx",IMMEDIATE,2,NULL
 OP_SBC_IZPX,"sbc",IZPX,2,NULL
@@ -229,7 +229,7 @@ OP_NOPI_E3,"nop",IMMEDIATE,2,NULL
 OP_NOPI_E4,"nop",IMPLIED,1,NULL
 OP_CPX_ZP,"cpx",ZP,2,NULL
 OP_SBC_ZP,"sbc",ZP,2,NULL
-OP_INC_ZP,"inc",ZP,2,NULL
+OP_INC_ZP,"inc",ZP,2,emul_inc
 OP_SMB6_ZP,"smb6",ZP,2,NULL
 OP_INX,"inx",IMPLIED,1,emul_inx
 OP_SBC_IMM,"sbc",IMMEDIATE,2,NULL
@@ -237,7 +237,7 @@ OP_NOP,"nop",IMPLIED,1,emul_nop
 OP_NOPI_EC,"nop",IMPLIED,1,NULL
 OP_CPX_ABS,"cpx",ABSOLUTE,3,NULL
 OP_SBC_ABS,"sbc",ABSOLUTE,3,NULL
-OP_INC_ABS,"inc",ABSOLUTE,3,NULL
+OP_INC_ABS,"inc",ABSOLUTE,3,emul_inc
 OP_BBS6_REL,"bbs6",ZPR,2,NULL
 OP_BEQ_REL,"beq",RELATIVE,2,NULL
 OP_SBC_IZPY,"sbc",IZPY,2,NULL
@@ -245,7 +245,7 @@ OP_SBC_IZP,"sbc",IZP,2,NULL
 OP_NOPI_F4,"nop",IMPLIED,1,NULL
 OP_NOPI_F5,"nop",ZPX,2,NULL
 OP_SBC_ZPX,"sbc",ZPX,2,NULL
-OP_INC_ZPX,"inc",ZPX,2,NULL
+OP_INC_ZPX,"inc",ZPX,2,emul_inc
 OP_SMB7_ZP,"smb7",ZP,2,NULL
 OP_SED,"sed",IMPLIED,1,NULL
 OP_SBC_ABSY,"sbc",ABSOLUTEY,3,NULL
@@ -253,5 +253,5 @@ OP_PLX,"plx",IMPLIED,1,emul_plx
 OP_NOPI_FC,"nop",IMPLIED,1,NULL
 OP_NOPI_FD,"nop",ABSOLUTE,3,NULL
 OP_SBC_ABSX,"sbc",ABSOLUTEX,3,NULL
-OP_INC_ABSX,"inc",ABSOLUTEX,3,NULL
+OP_INC_ABSX,"inc",ABSOLUTEX,3,emul_inc
 OP_BBS7_REL,"bbs7",ZPR,2,NULL
diff --git a/src/emulation.c b/src/emulation.c
index a342d95..c34e194 100644
--- a/src/emulation.c
+++ b/src/emulation.c
@@ -43,6 +43,21 @@ emul_clc(rk65c02emu_t *e, void *id, instruction_t *i)
 	e->regs.P &= ~P_CARRY;
 }
 
+/* DEC  - decrement memory location/acumulator */
+void
+emul_dec(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	uint8_t val;
+
+	/* this is absurdly inefficient */
+	val = instruction_data_read_1(e, (instrdef_t *) id, i);
+	val--;
+	instruction_data_write_1(e, id, i, val);
+
+	instruction_status_adjust_zero(e, val);
+	instruction_status_adjust_negative(e, val);
+}
+
 /* DNX - decrement X */
 void
 emul_dex(rk65c02emu_t *e, void *id, instruction_t *i)
@@ -73,6 +88,21 @@ emul_eor(rk65c02emu_t *e, void *id, instruction_t *i)
 	instruction_status_adjust_negative(e, e->regs.A);
 }
 
+/* INC - increment memory location/acumulator */
+void
+emul_inc(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+	uint8_t val;
+
+	/* this is absurdly inefficient */
+	val = instruction_data_read_1(e, (instrdef_t *) id, i);
+	val++;
+	instruction_data_write_1(e, id, i, val);
+
+	instruction_status_adjust_zero(e, val);
+	instruction_status_adjust_negative(e, val);
+}
+
 /* INX - increment X */
 void
 emul_inx(rk65c02emu_t *e, void *id, instruction_t *i)