diff --git a/Lib/YMF262-HAL/Inc/FakeGPIO.hpp b/Lib/YMF262-HAL/Inc/FakeGPIO.hpp
new file mode 100644
index 0000000..a117976
--- /dev/null
+++ b/Lib/YMF262-HAL/Inc/FakeGPIO.hpp
@@ -0,0 +1,19 @@
+#ifndef FAKE_GPIO_HPP
+#define FAKE_GPIO_HPP
+
+
+#include <cstdint>
+#include "GPIO.hpp"
+
+struct FakeGpio {
+    void set_data_bus(uint8_t val){}
+    void set_a0(Port port){}
+    void set_a1(Bank address_bank){}
+    void set_cs(State state){}
+    void set_wr(State state){}
+    void set_ic(State state){}
+    void set_rd(State state){}
+    void delay_ticks(uint32_t n){}
+};
+
+#endif
\ No newline at end of file
diff --git a/Lib/YMF262-HAL/Inc/GPIO.hpp b/Lib/YMF262-HAL/Inc/GPIO.hpp
new file mode 100644
index 0000000..cad421d
--- /dev/null
+++ b/Lib/YMF262-HAL/Inc/GPIO.hpp
@@ -0,0 +1,20 @@
+#ifndef GPIO_HPP
+#define GPIO_HPP
+
+enum class State{
+    ACTIVE,
+    INACTIVE
+};
+
+
+enum class Port{
+    DATA,
+    ADDRESS
+};
+
+enum class Bank{
+    BANK_0,
+    BANK_1,
+};
+
+#endif
\ No newline at end of file
diff --git a/Lib/YMF262-HAL/Inc/YMF262-HAL.hpp b/Lib/YMF262-HAL/Inc/YMF262-HAL.hpp
index 70d5a24..6c225fd 100644
--- a/Lib/YMF262-HAL/Inc/YMF262-HAL.hpp
+++ b/Lib/YMF262-HAL/Inc/YMF262-HAL.hpp
@@ -2,11 +2,13 @@
 #define YMF262_HAL_HPP
 
 #include <cstdint>
+#include "GPIO.hpp"
 
 template <class GPIOPolicy>
 class YMF262_HAL{
      private:
-    GPIOPolicy _gpio;
+    
+     GPIOPolicy _gpio;
     uint32_t _t_icw_ticks;
     uint32_t _t_as_ticks;
     uint32_t _t_ah_ticks;
@@ -19,6 +21,21 @@ class YMF262_HAL{
     uint32_t _t_acc_ticks;
     uint32_t _t_rdh_ticks;
     uint32_t _t_recovery_ticks;
+
+    void write_bus(Bank bank, Port port, uint8_t data){
+        _gpio.set_a0(port);
+        _gpio.set_a1(bank);
+        _gpio.delay_ticks(_t_as_ticks);
+        _gpio.set_cs(State::ACTIVE);
+        _gpio.set_wr(State::ACTIVE);
+        _gpio.set_data_bus(data);
+        _gpio.delay_ticks(_t_wds_ticks);
+        _gpio.set_wr(State::INACTIVE);
+        _gpio.set_cs(State::INACTIVE);
+        _gpio.delay_ticks(_t_wdh_ticks);
+        _gpio.delay_ticks(_t_recovery_ticks);
+
+    };
     
     public:
 
@@ -38,6 +55,12 @@ class YMF262_HAL{
         _t_acc_ticks   = (uint32_t)(150 * ticks_per_ns); 
         _t_rdh_ticks  = (uint32_t)(10  * ticks_per_ns);
     };
+
+    void write(Bank bank, uint8_t reg, uint8_t data){
+        write_bus(bank,Port::ADDRESS,reg);
+        write_bus(bank,Port::DATA,data);
+    };
+
 };
 
 #endif
\ No newline at end of file