diff --git a/src/emulation.awk b/src/emulation.awk
index ce360e7..deafbc9 100644
--- a/src/emulation.awk
+++ b/src/emulation.awk
@@ -14,7 +14,7 @@ BEGIN {
 
 END {
 	for (i in emuls)
-		printf "void %s(rk65c02emu_t *, instruction_t *);\n",i
+		printf "void %s(rk65c02emu_t *, void *id, instruction_t *);\n",i
 
 	print "#endif /* _EMULATION_H_ */"
 }
diff --git a/src/emulation.c b/src/emulation.c
index 16cae1a..96204e3 100644
--- a/src/emulation.c
+++ b/src/emulation.c
@@ -4,14 +4,11 @@
 
 /* AND - logical AND */
 void
-emul_and(rk65c02emu_t *e, instruction_t *i)
+emul_and(rk65c02emu_t *e, void *id, instruction_t *i)
 {
-	instrdef_t id;
 	uint8_t rv;
 
-	id = instruction_decode(i->opcode);
-
-	rv = e->regs.A & (instruction_data_read_1(e, &id, i));
+	rv = e->regs.A & (instruction_data_read_1(e, (instrdef_t *) id, i));
 	e->regs.A = rv;
 
 	instruction_status_adjust_zero(e, e->regs.A);
@@ -20,13 +17,9 @@ emul_and(rk65c02emu_t *e, instruction_t *i)
 
 /* LDA - load to accumulator */
 void
-emul_lda(rk65c02emu_t *e, instruction_t *i)
+emul_lda(rk65c02emu_t *e, void *id, instruction_t *i)
 {
-	instrdef_t id;
-
-	id = instruction_decode(i->opcode);
-
-	e->regs.A = instruction_data_read_1(e, &id, i);
+	e->regs.A = instruction_data_read_1(e, (instrdef_t *) id, i);
 
 	instruction_status_adjust_zero(e, e->regs.A);
 	instruction_status_adjust_negative(e, e->regs.A);
@@ -34,21 +27,20 @@ emul_lda(rk65c02emu_t *e, instruction_t *i)
 
 /* NOP - do nothing */
 void
-emul_nop(rk65c02emu_t *e, instruction_t *i)
+emul_nop(rk65c02emu_t *e, void *id, instruction_t *i)
 {
-	/* printf("nop!\n"); */
 }
 
 /* PHA - push accumulator to stack */
 void
-emul_pha(rk65c02emu_t *e, instruction_t *i)
+emul_pha(rk65c02emu_t *e, void *id, instruction_t *i)
 {
 	stack_push(e, e->regs.A);
 }
 
 /* PLA - pull from stack to accumulator */
 void
-emul_pla(rk65c02emu_t *e, instruction_t *i)
+emul_pla(rk65c02emu_t *e, void *id, instruction_t *i)
 {
 	e->regs.A = stack_pop(e);
 
@@ -58,19 +50,15 @@ emul_pla(rk65c02emu_t *e, instruction_t *i)
 
 /* STP - stop the processor */
 void
-emul_stp(rk65c02emu_t *e, instruction_t *i)
+emul_stp(rk65c02emu_t *e, void *id, instruction_t *i)
 {
 	e->state = STOPPED;
 }
 
 /* STZ - store zero */
 void
-emul_stz(rk65c02emu_t *e, instruction_t *i)
+emul_stz(rk65c02emu_t *e, void *id, instruction_t *i)
 {
-	instrdef_t id;
-
-	id = instruction_decode(i->opcode);
-
-	instruction_data_write_1(e, &id, i, 0);
+	instruction_data_write_1(e, id, i, 0);
 }
 
diff --git a/src/instruction.c b/src/instruction.c
index 4acc7d2..ca2dbb1 100644
--- a/src/instruction.c
+++ b/src/instruction.c
@@ -278,3 +278,10 @@ stack_pop(rk65c02emu_t *e)
 	return val;
 }
 
+/* increment program counter based on instruction size (opcode + operands) */ 
+void
+program_counter_increment(rk65c02emu_t *e, instrdef_t *id)
+{
+	e->regs.PC += id->size;
+}	
+
diff --git a/src/instruction.h b/src/instruction.h
index 7816538..01fc654 100644
--- a/src/instruction.h
+++ b/src/instruction.h
@@ -34,7 +34,7 @@ struct instrdef {
 	const char *mnemonic;
 	addressing_t mode;
 	uint8_t size;
-	void (*emul)(rk65c02emu_t *e, instruction_t *i);
+	void (*emul)(rk65c02emu_t *e, void *id, instruction_t *i);
 };
 
 typedef struct instrdef instrdef_t;
@@ -49,5 +49,6 @@ void instruction_status_adjust_zero(rk65c02emu_t *, uint8_t);
 void instruction_status_adjust_negative(rk65c02emu_t *, uint8_t);
 void stack_push(rk65c02emu_t *, uint8_t);
 uint8_t stack_pop(rk65c02emu_t *);
+void program_counter_increment(rk65c02emu_t *, instrdef_t *);
 
 #endif /* _INSTRUCTION_H_ */
diff --git a/src/rk65c02.c b/src/rk65c02.c
index c59f942..50417d9 100644
--- a/src/rk65c02.c
+++ b/src/rk65c02.c
@@ -32,16 +32,15 @@ rk65c02_start(rk65c02emu_t *e) {
 		i = instruction_fetch(e->bus, e->regs.PC);
 		id = instruction_decode(i.opcode);
 
-		if (id.emul != NULL)
-			id.emul(e, &i);
-		else {
+		if (id.emul != NULL) {
+			id.emul(e, &id, &i);
+			/* if (!instruction_modify_pc) */
+			program_counter_increment(e, &id);
+		} else {
 			printf("unimplemented opcode %X @ %X\n", i.opcode,
 			    e->regs.PC);
 			e->state = STOPPED;
 		}
-
-		e->regs.PC += id.size;
-
 	}
 }
 /*