diff --git a/src/65c02isa.csv b/src/65c02isa.csv
index c832670..61bd066 100644
--- a/src/65c02isa.csv
+++ b/src/65c02isa.csv
@@ -70,7 +70,7 @@ OP_NOPI_45,"nop",ZP,2,NULL
 OP_EOR_ZP,"eor",ZP,2,NULL
 OP_LSR_ZP,"lsr",ZP,2,NULL
 OP_RMB4_ZP,"rmb4",ZP,2,NULL
-OP_PHA,"pha",IMPLIED,1,NULL
+OP_PHA,"pha",IMPLIED,1,emul_pha
 OP_EOR_IMM,"eor",IMMEDIATE,2,NULL
 OP_LSR,"lsr",ACCUMULATOR,1,NULL
 OP_NOPI_4C,"nop",IMPLIED,1,NULL
@@ -102,7 +102,7 @@ OP_STZ_ZP,"stz",ZP,2,NULL
 OP_ADC_ZP,"adc",ZP,2,NULL
 OP_ROR_ZP,"ror",ZP,2,NULL
 OP_RMB6_ZP,"rmb6",ZP,2,NULL
-OP_PLA,"pla",IMPLIED,1,NULL
+OP_PLA,"pla",IMPLIED,1,emul_pla
 OP_ADC_IMM,"adc",IMMEDIATE,2,NULL
 OP_ROR,"ror",ACCUMULATOR,1,NULL
 OP_NOPI_6C,"nop",IMPLIED,1,NULL
diff --git a/src/emulation.c b/src/emulation.c
index 4cffcc4..c14c886 100644
--- a/src/emulation.c
+++ b/src/emulation.c
@@ -2,13 +2,15 @@
 
 #include "emulation.h"
 
+/* AND - logical AND */
 void
 emul_and(rk65c02emu_t *e, instruction_t *i)
 {
 	instrdef_t id;
-	id = instruction_decode(i->opcode);
 	uint8_t rv;
 
+	id = instruction_decode(i->opcode);
+
 	rv = e->regs.A & (instruction_data_read_1(e, &id, i));
 	e->regs.A = rv;
 
@@ -16,10 +18,12 @@ emul_and(rk65c02emu_t *e, instruction_t *i)
 	instruction_status_adjust_negative(e, e->regs.A);
 }
 
+/* LDA - load to accumulator */
 void
 emul_lda(rk65c02emu_t *e, instruction_t *i)
 {
 	instrdef_t id;
+
 	id = instruction_decode(i->opcode);
 
 	e->regs.A = instruction_data_read_1(e, &id, i);
@@ -28,12 +32,31 @@ emul_lda(rk65c02emu_t *e, instruction_t *i)
 	instruction_status_adjust_negative(e, e->regs.A);
 }
 
+/* NOP - do nothing */
 void
 emul_nop(rk65c02emu_t *e, instruction_t *i)
 {
 	/* printf("nop!\n"); */
 }
 
+/* PHA - push accumulator to stack */
+void
+emul_pha(rk6502emu_t *e, instruction_t *i)
+{
+	stack_push(e, e->regs.A);
+}
+
+/* PLA - pull from stack to accumulator */
+void
+emul_pla(rk65c02emu_t *e, instruciton_t *i)
+{
+	e->regs.A = stack_pop(e);
+
+	instruction_status_adjust_zero(e, e->regs.A);
+	instruction_status_adjust_negative(e, e->regs.A);
+}
+
+/* STP - stop the processor */
 void
 emul_stp(rk65c02emu_t *e, instruction_t *i)
 {