Split bios in multiple asm files

assembly/bios/Makefile

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+bios:
+	z80asm -i main.asm -o rom.bin
+	dd if=/dev/zero of=rom.bin bs=1 count=0 seek=8192
+	minipro -w rom.bin -p "AT28C64B"
+	

assembly/bios/driver_hd44780.asm

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+; HD44780 20x4 characters LCD display driver
+; @author Daniele Verducci
+
+
+; functions
+
+lcd_init:
+    ;reset procedure
+    ld a,0x38
+    out (LCD_INSTR_REG),a
+    ld a,0x08
+    out (LCD_INSTR_REG),a
+    ld a,0x01
+    out (LCD_INSTR_REG),a
+
+    ;init procedure
+    ld a,0x38
+    out (LCD_INSTR_REG),a
+    ld a,0x0F
+    out (LCD_INSTR_REG),a
+
+    ret
+
+; Writes text starting from current cursor position
+; @param BC Pointer to a null-terminated string first character
+lcd_print:
+    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_print
+
+; Set cursor position
+; @param B X-axis position (0 to 19)
+; @param C Y-axis position (0 to 3)
+lcd_locate:
+    ; TODO
+    ret
+
+; Clears the screen
+lcd_cls:
+    ld a,0x01
+    out (LCD_INSTR_REG),a   ; clear display
+    ld a,0x02
+    out (LCD_INSTR_REG),a   ; cursor to home (top left)
+    ret

assembly/bios/main.asm

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+; Pat80 BIOS v0.01
+; @author: Daniele Verducci
+; 
+; ROM is at 0x00
+; RAM is at 0x80
+; LCD is at I/O 0x00 and 0x01
+
+
+
+jp sysinit     ; Startup vector: DO NOT MOVE! Must be the first instruction
+
+
+; SYSTEM CONFIGURATION
+LCD_INSTR_REG: EQU %00000000
+LCD_DATA_REG: EQU %00000001
+
+
+; CONSTANTS
+SYSINIT_GREETING:
+    DB "Pat80 BIOS v0.1",0  ; null terminated string
+LIPSUM:
+    DB "Lorem ipsum dolor sit amet, consectetur adipiscing elit.",0
+
+
+
+
+
+include 'driver_hd44780.asm'
+
+; System initialization
+sysinit:
+    call lcd_init
+
+    ; write characters to display
+    ld bc, SYSINIT_GREETING
+    call lcd_print      ; write string to screen
+
+    ld bc, LIPSUM
+    call lcd_print
+
+    ;call lcd_cls        ; clear screen
+
+    halt
+
+
+