Working LCD!

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"
+	

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"

assembly/hd44780_lcd_test_procedure.asm

@@ -36,4 +36,3 @@ ld a,%00100001
 out (LCD_DATA_REG),a
 
 halt
-

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