diff --git a/arduino/hd44780_debugger/hd44780_debugger.ino b/arduino/hd44780_debugger/hd44780_debugger.ino
index 99d1221..217276d 100644
--- a/arduino/hd44780_debugger/hd44780_debugger.ino
+++ b/arduino/hd44780_debugger/hd44780_debugger.ino
@@ -1,11 +1,9 @@
 /* HD44780 Character display debugger */
 
-#define EN 2
-#define RS 11
-const byte DATA_BUS[] = {10, 9, 8, 7, 6, 5, 4, 3};
+#define EN 11
+const byte DATA_BUS[] = {3, 4, 5, 6, 7, 8, 9, 10};
 
 void setup() {
-  pinMode(RS, INPUT);
   pinMode(EN, INPUT);
   for(int pin=0; pin < 8; pin++) {
     pinMode(DATA_BUS[pin], INPUT);
@@ -13,9 +11,9 @@ void setup() {
 
   Serial.begin(57600);
   Serial.println("HD44780 debugger");
-  Serial.println("DATA BUS    HEX     RS   EN");
+  Serial.println("DATA BUS    HEX     EN");
 
-  attachInterrupt(digitalPinToInterrupt(EN), onClk, CHANGE);
+  attachInterrupt(digitalPinToInterrupt(2), onClk, FALLING);
 }
 
 void loop() {}
@@ -28,7 +26,10 @@ void onClk() {
       data = (data << 1) + b;   // Shifta di 1 e aggiunge il bit corrente. Serve per ricostruire il numero da binario
     }
     
-    char output[30] = {};
-    sprintf(output, "    0x%02x    %c    %c", data, digitalRead(RS) ? 'D' : 'I', digitalRead(EN) ? 'H' : 'L');
+    char output[50] = {};
+    sprintf(output, "    0x%02x    %c", 
+      data, 
+      digitalRead(EN) ? 'D' : 'I'
+    );
     Serial.println(output);
 }
diff --git a/assembly/Makefile b/assembly/Makefile
new file mode 100644
index 0000000..f2da4c7
--- /dev/null
+++ b/assembly/Makefile
@@ -0,0 +1,5 @@
+bios:
+	z80asm -i pat80_bios_0.1.asm -o rom.bin
+	dd if=/dev/zero of=rom.bin bs=1 count=0 seek=8192
+	minipro -w rom.bin -p "AT28C64B"
+	
\ No newline at end of file
diff --git a/assembly/README.txt b/assembly/README.txt
index 2fa65c5..1750da4 100644
--- a/assembly/README.txt
+++ b/assembly/README.txt
@@ -4,4 +4,5 @@ Portare binario alla dimensione dell eeprom:
     dd if=/dev/zero of=rom.bin bs=1 count=0 seek=8192
 Scrivere su EEPROM:
     minipro -w rom.bin -p "AT28C64B"
-
+Leggere EEPROM:
+    minipro -r rom_read.bin -p "AT28C64B"
diff --git a/assembly/hd44780_lcd_test_procedure.asm b/assembly/hd44780_lcd_test_procedure.asm
index 7a03183..e32f1cd 100644
--- a/assembly/hd44780_lcd_test_procedure.asm
+++ b/assembly/hd44780_lcd_test_procedure.asm
@@ -36,4 +36,3 @@ ld a,%00100001
 out (LCD_DATA_REG),a
 
 halt
-
diff --git a/assembly/pat80_bios_0.1.asm b/assembly/pat80_bios_0.1.asm
new file mode 100644
index 0000000..78339e2
--- /dev/null
+++ b/assembly/pat80_bios_0.1.asm
@@ -0,0 +1,41 @@
+; SYSTEM CONFIGURATION
+LCD_INSTR_REG: EQU %00000000
+LCD_DATA_REG: EQU %00000001
+
+; System initialization
+call lcd_init
+
+; write characters to display
+ld bc, hello_world
+call lcd_write      ; write string to screen
+
+halt
+
+
+lcd_init:
+    ;reset procedure
+    ld a,%00111000
+    out (LCD_INSTR_REG),a
+    ld a,%00001000
+    out (LCD_INSTR_REG),a
+    ld a,%00000001
+    out (LCD_INSTR_REG),a
+
+    ;init procedure
+    ld a,%00111000
+    out (LCD_INSTR_REG),a
+    ld a,%00001110
+    out (LCD_INSTR_REG),a
+
+    ret
+
+lcd_write:
+    ld a, (bc)  ; bc is the pointer to passed string's first char
+    cp 0        ; compare A content with 0 (subtract 0 from value and set zero flag Z if result is 0)
+    ret z       ; if prev compare is true (Z flag set), string is finished, return
+    out (LCD_DATA_REG),a    ; output char
+    inc bc ; increment bc to move to next char
+    jp lcd_write
+
+hello_world:
+    DB "Lorem ipsum",0  ; null terminated string
\ No newline at end of file