ZX Spectrum - 4 colors at one char position demo

zx_4color.asm

basic48_cls equ 0x0D6B

	org	25000
	
	ld a, 00000111b ; PAPER 0, INK 7
	ld (iy + 83), a ; ATTR-P
	xor a ; BORDER 0
	out (0xFE), a
	ld (iy + 14), a ; BORDCR
	call basic48_cls
	
im2_prepare:
	ld a, 0xBD
	ld i, a
	ld h, a
	ld l, 0
	ld d, h
	ld e, 1
	ld bc, 256
	ld a, 0xBE
	ld (hl), a
	ldir
	
im2_copy_jump:
	ld hl, im2_jump
	ld e, a
	ld d, a ; 0xBEBE
	ld bc, 3
	ldir
	
im2_start:	
	im 2
	
forever_loop:
	ei 
	jr forever_loop
	
im2_jump:
	jp im2_handler
	
im2_handler:
	di
	ld a, (counter)
	push af
	inc a
	ld (counter), a	
	pop af
	bit 0, a
	call z, set_pattern1
	call nz, set_pattern2
  ld b, 30
  put_char: 
      push hl
      push bc
      
    apply_pattern:
        ld a, (hl)
        ld de, (attr_ptr)
        ld (de), a
        inc hl
        ld de, (pixel_ptr)
        ld b, 8
    apply_pattern_loop:	
        ld a, (hl)
        ld (de), a
        inc hl
        inc d
      djnz apply_pattern_loop
      
      ld hl, (attr_ptr)
      inc hl
      ld (attr_ptr), hl
      ld hl, (pixel_ptr)
      inc hl
      ld (pixel_ptr), hl  
      
      pop bc  
      pop hl
    djnz put_char
  ld hl, 0x5901
  ld (attr_ptr), hl
  ld hl, 0x4801
  ld (pixel_ptr), hl
	ret

set_pattern1:
	ld hl, color1
	ret
set_pattern2:
	ld hl, color2
	ret
	
counter db 0
attr_ptr dw 0x5901
pixel_ptr dw 0x4801

IF 1
color1 db 01110011b
pattern1:
	db 00011000b
	db 01100110b
	db 01100110b
	db 10011001b
	db 10011001b
	db 01100110b
	db 01100110b
	db 00011000b

color2 db 01100111b
pattern2:
	db 00011000b
	db 01111110b
	db 01111110b
	db 11100111b
	db 11100111b
	db 01111110b
	db 01111110b
	db 00011000b
ENDIF