diff --git a/src/65c02isa.csv b/src/65c02isa.csv
index af8f108..c602e34 100644
--- a/src/65c02isa.csv
+++ b/src/65c02isa.csv
@@ -35,7 +35,7 @@ OP_JSR,"jsr",ABSOLUTE,3,NULL
 OP_AND_IZPX,"and",IZPX,2,emul_and
 OP_NOPI_23,"nop",IMMEDIATE,2,NULL
 OP_NOPI_24,"nop",IMPLIED,1,NULL
-OP_BIT_ZP,"bit",ZP,2,NULL
+OP_BIT_ZP,"bit",ZP,2,emul_bit
 OP_AND_ZP,"and",ZP,2,emul_and
 OP_ROL_ZP,"rol",ZP,2,emul_rol
 OP_RMB2_ZP,"rmb2",ZP,2,NULL
@@ -43,7 +43,7 @@ OP_PLP,"plp",IMPLIED,1,emul_plp
 OP_AND_IMM,"and",IMMEDIATE,2,emul_and
 OP_ROL,"rol",ACCUMULATOR,1,emul_rol
 OP_NOPI_2C,"nop",IMPLIED,1,NULL
-OP_BIT_ABS,"bit",ABSOLUTE,3,NULL
+OP_BIT_ABS,"bit",ABSOLUTE,3,emul_bit
 OP_AND_ABS,"and",ABSOLUTE,3,emul_and
 OP_ROL_ABS,"rol",ABSOLUTE,3,emul_rol
 OP_BBR2_REL,"bbr2",ZPR,2,NULL
@@ -51,7 +51,7 @@ OP_BMI_REL,"bmi",RELATIVE,2,NULL
 OP_AND_IZPY,"and",IZPY,2,emul_and
 OP_AND_IZP,"and",IZP,2,emul_and
 OP_NOPI_34,"nop",IMPLIED,1,NULL
-OP_BIT_ZPX,"bit",ZPX,2,NULL
+OP_BIT_ZPX,"bit",ZPX,2,emul_bit
 OP_AND_ZPX,"and",ZPX,2,emul_and
 OP_ROL_ZPX,"rol",ZPX,2,emul_rol
 OP_RMB3_ZP,"rmb3",ZP,2,NULL
@@ -59,7 +59,7 @@ OP_SEC,"sec",IMPLIED,1,emul_sec
 OP_AND_ABSY,"and",ABSOLUTEY,3,emul_and
 OP_DEC,"dec",ACCUMULATOR,1,NULL
 OP_NOPI_3C,"nop",IMPLIED,1,NULL
-OP_BIT_ABSX,"bit",ABSOLUTEX,3,NULL
+OP_BIT_ABSX,"bit",ABSOLUTEX,3,emul_bit
 OP_AND_ABSX,"and",ABSOLUTEX,3,emul_and
 OP_ROL_ABSX,"rol",ABSOLUTEX,3,emul_rol
 OP_BBR3_REL,"bbr3",ZPR,2,NULL
@@ -136,7 +136,7 @@ OP_STA_ZP,"sta",ZP,2,emul_sta
 OP_STX_ZP,"stx",ZP,2,emul_stx
 OP_SMB0_ZP,"smb0",ZP,2,NULL
 OP_DEY,"dey",IMPLIED,1,emul_dey
-OP_BIT_IMM,"bit",IMMEDIATE,2,NULL
+OP_BIT_IMM,"bit",IMMEDIATE,2,emul_bit
 OP_TXA,"txa",IMPLIED,1,emul_txa
 OP_NOPI_8C,"nop",IMPLIED,1,NULL
 OP_STY_ABS,"sty",ABSOLUTE,3,emul_sty
diff --git a/src/emulation.c b/src/emulation.c
index 3f2fb37..5d70c81 100644
--- a/src/emulation.c
+++ b/src/emulation.c
@@ -12,6 +12,30 @@ emul_and(rk65c02emu_t *e, void *id, instruction_t *i)
 	instruction_status_adjust_negative(e, e->regs.A);
 }
 
+/* BIT - check if one or more bits are set */
+void
+emul_bit(rk65c02emu_t *e, void *id, instruction_t *i)
+{
+/*	uint8_t v = instruction_data_read_1(e, (instrdef_t *) id, i);
+	printf("%x\n", v);*/
+
+	/* zero flag set if acculumator AND memory equals zero */
+	if (e->regs.A & instruction_data_read_1(e, (instrdef_t *) id, i))
+		e->regs.P &= ~P_ZERO;
+	else
+		e->regs.P |= P_ZERO;
+
+	if (BIT(instruction_data_read_1(e, (instrdef_t *) id, i), 6))
+		e->regs.P |= P_SIGN_OVERFLOW;
+	else
+		e->regs.P &= ~P_SIGN_OVERFLOW;
+
+	if (BIT(instruction_data_read_1(e, (instrdef_t *) id, i), 7))
+		e->regs.P |= P_NEGATIVE;
+	else
+		e->regs.P &= ~P_NEGATIVE;
+}
+
 /* CLC - clear carry flag */
 void
 emul_clc(rk65c02emu_t *e, void *id, instruction_t *i)
diff --git a/test/test_emulation.c b/test/test_emulation.c
index 18c6f15..696e31d 100644
--- a/test/test_emulation.c
+++ b/test/test_emulation.c
@@ -22,6 +22,55 @@ rom_start(rk65c02emu_t *e, const char *name)
 	return true;
 }
 
+ATF_TC_WITHOUT_HEAD(emul_bit);
+ATF_TC_BODY(emul_bit, tc)
+{
+	rk65c02emu_t e;
+	bus_t b;
+
+	b = bus_init();
+	e = rk65c02_init(&b);
+
+	/* BIT immediate  */
+	e.regs.A = 0x40;
+	ATF_REQUIRE(rom_start(&e, "test_emulation_bit_imm.rom"));
+	ATF_CHECK(!(e.regs.P & P_ZERO));
+	ATF_CHECK(e.regs.P & P_SIGN_OVERFLOW);
+	ATF_CHECK(!(e.regs.P & P_NEGATIVE));
+	/* BIT zero page */
+	e.regs.A = 0x40;
+	bus_write_1(&b, 0x10, 0x80);
+	ATF_REQUIRE(rom_start(&e, "test_emulation_bit_zp.rom"));
+	ATF_CHECK(e.regs.P & P_ZERO);
+	ATF_CHECK(!(e.regs.P & P_SIGN_OVERFLOW));
+	ATF_CHECK(e.regs.P & P_NEGATIVE);
+	/* BIT zero page X */
+	e.regs.A = 0x40;
+	e.regs.X = 0x1;
+	bus_write_1(&b, 0x10, 0x40);
+	ATF_REQUIRE(rom_start(&e, "test_emulation_bit_zpx.rom"));
+	ATF_CHECK(!(e.regs.P & P_ZERO));
+	ATF_CHECK(e.regs.P & P_SIGN_OVERFLOW);
+	ATF_CHECK(!(e.regs.P & P_NEGATIVE));
+	/* BIT absolute */
+	e.regs.A = 0x80;
+	bus_write_1(&b, 0x2010, 0x80);
+	ATF_REQUIRE(rom_start(&e, "test_emulation_bit_abs.rom"));
+	ATF_CHECK(!(e.regs.P & P_ZERO));
+	ATF_CHECK(!(e.regs.P & P_SIGN_OVERFLOW));
+	ATF_CHECK(e.regs.P & P_NEGATIVE);
+	/* BIT absolute X */
+	e.regs.A = 0x40;
+	e.regs.X = 0x2;
+	bus_write_1(&b, 0x2010, 0x80);
+	ATF_REQUIRE(rom_start(&e, "test_emulation_bit_absx.rom"));
+	ATF_CHECK(e.regs.P & P_ZERO);
+	ATF_CHECK(!(e.regs.P & P_SIGN_OVERFLOW));
+	ATF_CHECK(e.regs.P & P_NEGATIVE);
+
+	bus_finish(&b);
+}
+
 ATF_TC_WITHOUT_HEAD(emul_dex_dey);
 ATF_TC_BODY(emul_dex_dey, tc)
 {
@@ -424,6 +473,7 @@ ATF_TC_BODY(emul_php_plp, tc)
 ATF_TP_ADD_TCS(tp)
 {
 	ATF_TP_ADD_TC(tp, emul_and);
+	ATF_TP_ADD_TC(tp, emul_bit);
 	ATF_TP_ADD_TC(tp, emul_dex_dey);
 	ATF_TP_ADD_TC(tp, emul_clc_sec);
 	ATF_TP_ADD_TC(tp, emul_inx_iny);
diff --git a/test/test_emulation_bit_abs.s b/test/test_emulation_bit_abs.s
new file mode 100644
index 0000000..39ea483
--- /dev/null
+++ b/test/test_emulation_bit_abs.s
@@ -0,0 +1,3 @@
+start:	bit 0x2010
+	stp
+
diff --git a/test/test_emulation_bit_absx.s b/test/test_emulation_bit_absx.s
new file mode 100644
index 0000000..138971c
--- /dev/null
+++ b/test/test_emulation_bit_absx.s
@@ -0,0 +1,3 @@
+start:	bit 0x200E,X
+	stp
+
diff --git a/test/test_emulation_bit_imm.s b/test/test_emulation_bit_imm.s
new file mode 100644
index 0000000..f2f0d77
--- /dev/null
+++ b/test/test_emulation_bit_imm.s
@@ -0,0 +1,3 @@
+start:	bit #0x55
+	stp
+
diff --git a/test/test_emulation_bit_zp.s b/test/test_emulation_bit_zp.s
new file mode 100644
index 0000000..6781a30
--- /dev/null
+++ b/test/test_emulation_bit_zp.s
@@ -0,0 +1,3 @@
+start:	bit 0x10
+	stp
+
diff --git a/test/test_emulation_bit_zpx.s b/test/test_emulation_bit_zpx.s
new file mode 100644
index 0000000..83409cc
--- /dev/null
+++ b/test/test_emulation_bit_zpx.s
@@ -0,0 +1,3 @@
+start:	bit 0xF,X
+	stp
+