Experimenting with lcd cursor location instructions

assembly/bios/driver_hd44780.asm

@@ -1,6 +1,9 @@
 ; HD44780 20x4 characters LCD display driver
 ; @author Daniele Verducci
 
+; variables
+;lcd_cur_x: EQU DRV_VAR_SPACE
+;lcd_cur_y: lcd_cur_x + 1
 
 ; functions
 
@@ -36,7 +39,10 @@ lcd_print:
 ; @param B X-axis position (0 to 19)
 ; @param C Y-axis position (0 to 3)
 lcd_locate:
-    ; TODO
+    ld a,0xFE
+    out (LCD_INSTR_REG),a   ; warns the lcd microcontroller that a command is coming
+    ld a,0xA8
+    out (LCD_INSTR_REG),a   ; place cursor to first char of second line
     ret
 
 ; Clears the screen

assembly/bios/main.asm

@@ -1,8 +1,11 @@
 ; Pat80 BIOS v0.01
 ; @author: Daniele Verducci
 ; 
-; ROM is at 0x00
-; RAM is at 0x80
+; ROM is at 0x0000
+; RAM is at 0x8000
+;   SYSTEM VAR SPACE: 0x8000 - 0x8FFF (4kb)
+;   DRIVERS VAR SPACE: 0x9000 - 0x9FFF (4kb)
+;   APPLICATION VAR SPACE: 0xA000 - 0xFFFF (24kb)
 ; LCD is at I/O 0x00 and 0x01
 
 
@@ -13,6 +16,9 @@ jp sysinit     ; Startup vector: DO NOT MOVE! Must be the first instruction
 ; SYSTEM CONFIGURATION
 LCD_INSTR_REG: EQU %00000000
 LCD_DATA_REG: EQU %00000001
+SYS_VAR_SPACE: EQU 0x8000
+DRV_VAR_SPACE: EQU 0x9000
+APP_VAR_SPACE: EQU 0xA000
 
 
 ; CONSTANTS
@@ -35,12 +41,29 @@ sysinit:
     ld bc, SYSINIT_GREETING
     call lcd_print      ; write string to screen
 
+    call lcd_locate
+
     ld bc, LIPSUM
     call lcd_print
 
     ;call lcd_cls        ; clear screen
 
+    ;call count
+
     halt
 
 
+; count:
+;     myVar: EQU APP_VAR_SPACE   ; init variable
+;     ld hl, "A"          ; load value into register
+;     ld (myVar), hl      ; copy value into variable
+;     call count_loop
 
+; count_loop:
+;     ld bc, myVar
+;     call lcd_print
+;     ; increm var
+;     ld a, (myVar)
+;     inc a
+;     ld (myVar), a
+;     call count_loop