Create assembler_8048_videopac.asm

a/assembler_8048_videopac.asm

@@ -0,0 +1,50 @@
+
+; Hello World for Philips Videopac (Magnavox Odyssey 2)
+; by Frog ( https://github.com/petersobolev )
+; 25 July 2016
+
+	cpu	8048
+	org	400h
+
+; interrupt vectors
+	jmp     02C3h                           ; selectgame (RESET)
+	jmp     0009h                           ; irq
+	jmp	timer                           ; timer
+	jmp	001Ah                           ; vsyncirq
+	jmp	start                           ; after selectgame
+	jmp	0044h                           ; soundirq
+
+timer:
+	ret                                     ; no timer needed
+
+
+start:
+
+	call	011Ch                           ; gfxoff
+
+	mov	r0,#010h                        ; pointer in VDC - which char to display (one of 12)
+	mov	r3,#40                          ; x
+	mov	r4,#100                         ; y
+	mov	r1,#hellostr & 0ffh             ; string to print (should be on same 255 bytes page)
+
+	mov	r2,#11                          ; string length
+
+nextchar:
+	mov	a,r1
+	movp	a,@a                            ; get char located at @r1
+	mov	r5,a
+	inc	r1                              ; inc addr of char
+	mov	r6,#0eh                         ; white color
+	call	03EAh                           ; printchar bios subroutine (increases r0, r3)
+	djnz	r2,nextchar
+
+	call	0127h                           ; gfxon (show what is written to VDC)
+
+
+loop:
+	jmp 	loop                            ; just wait and do nothing
+
+; 'HELLO WORLD' (ascii not supported by assembler)
+hellostr:
+	db 	01dh, 012h, 00eh, 00eh, 017h, 00ch, 011h, 017h, 013h, 00eh, 01ah
+