C128_GraphicsMultiColorAssemblyInfo

lived.ch, 12:50 04.03.2024

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Standard Graphic Modes


Text Mode

	lda #$00, sta $d8 

Graphic 1 {full screen 16 colors high resolution,  320 x 200 }

	lda #$20, sta $d8

Graphic 2 {split screen 16 colors high resolution  320 x xxx }

	lda #$60, sta $d8, *depending on text part

Graphic 3 {full screen multi color low resolution  160 x 200 } 

	lda #$a0, sta $d8
	
Graphic 4 {split screen multi color low resolution 160 x xxx }

	lda #$e0, sta $d8, *depending on text part

Update 22.02.2024 	{ this Multi Color resolution is quite misleading if you take it for granted 	}	
			{ the actual horizontal resolution is still 320, meaning if you do:		}
			{ 10		ldx#$00								}
			{ 20 loop	lda #$ff							}
			{ 30		sta $2000,x							}
			{ 40		inx								}	
			{ 50		cpx #$a0 -> = dec 160 and it should be right end of the screen	}
			{ 60		bne loop							}
			{ it will draw only until middle of the screen, not to the very right end!	}
			{ in MultiColor, 1 pixel is 'converted to 2 pixels, horizontally and that why	}
			{ the resolution is 160, not 320, but that's wrong! You still need to address	}
			{ both location, not just one! Ergo, you need a value of 320 to reach right end }
			{ and not 160, like the resolution numbers are suggesting.			}

			{ and on top of that, the GRAPHIC 4 mode is buggy and it isn't update the values}
			{ after you called the mandatory SCNCLR 4 or GRAPHIC 4,1 {1 stands for deletion}}
			{ solution is to call SCNCLR 3 or GRAPHIC 3,1 and then switch to GRAPHIC 4,0,x	}
			{ x = split-screen value for GRAPHIC/TEXT mode					}
			{ Now the problems is, i don't see nowhere the information of how to do that in	}
			{ assembly? Not in one single book for C128 i read is this information available}
			{ for now i used therefore BASIC/Assembly mix to achieve what i wanted 		}
			{ check MultiColor Graphic examples!						}

Split Screen Line 16 { Mode 2, 4 }	= lda #$b0, sta $0a34


* Split screen raster line is set using register $0a34, dec 2612
  If split screen is set, value hier is copied to $d012, dec 53266 to position the raster line
  To position it properly: ( row line * 8 ) + 48
  Default value is 208 = scanline of 20 (208-48) = 160 / 8 = 20


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Hires Graphics

Drawing Color 		{ first half of the byte with values 	#$0 - #$f }
Background Color 	{ 2nd half of the byte with values 	#$0 - #$f }

{ e.g lda #$06, [0 ist first half], [6 is second half] in sta $03e2 means black drawing color on blue background }  

Colors		Value		Address	

black		lda #$06	sta $03e2

white		lda #$16	sta $03e2
red		lda #$26	sta $03e2
cyan		lda #$36	sta $03e2
purple		lda #$46	sta $03e2
green		lda #$56	sta $03e2

dark blue	lda #$66	sta $03e2
yellow		lda #$76	sta $03e2
orange		lda #$86	sta $03e2
brown		lda #$96	sta $03e2
light red	lda #$a6	sta $03e2

dark grey	lda #$b6	sta $03e2
medium grey	lda #$c6	sta $03e2
light green	lda #$d6	sta $03e2
light blue	lda #$e6	sta $03e2
light grey	lda #$f6	sta $03e2


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MultiColorMode Graphic 3 and 4: (low res)

This is initial routine i managed to put together to actually update the colors
after the change. First is the activation of Graphic 3 mode, then delete and update everything.
Eventually you can call the drawings data...
and switch to Graphic 4 (graphic/Text) if you want or just don't call it to remain in Graphic 3, full screen mode.

(see examples available for download for better understanding)

mcgfx1.asm         -e:0064-a:    -e:


 init0   lda #$00      ;bank 15
         sta $ff00
         lda #$a0      ;graphic 3
         sta $d8       ;mode
         lda #$03      ;
         sta $83       ;multicolor
         lda #$05
         sta $84       ;color 2,x
         lda #$0b
         sta $85       ;color 3,x
         lda #$0c
         sta $86       ;color 1,x
         lda #$00
         sta $d020     ;border color
         lda #$00
         sta $d021     ;screen color
         lda #$0e
         sta $f1       ;text color
         lda #$a0      ;mc graphic 3
         jsr $6acd     ;deletion 'cos
         jsr $6ad0     ;graph 4 is buggy
         jsr $6ad3     ;and causing
         jsr $6a5c     ;troubles
         jsr $6b30
         rts
 init2   lda #$e0      ;switch mode
         sta $d8       ;graph/text
         lda #144      ;raster (12)
         sta $0a34
         rts