Sprite port-mirror Attribute 4 Register

Number	$39
Readable	No
Writable	Yes
Short Description	Nextreg port-mirror to write directly into "byte 5" of Sprite Attribute Upload ($xx57 / 87).

Byte 5 is bitmapped:

For anchor sprites:

Bit	Description
7-6	"H N6" - "H" is 4/8 bit graphics selector, "N6" is sub-pattern selector for 4 bit modes. %00 = 8-bit colour patterns (256 bytes), this sprite is "anchor" %01 = this sprite is "relative" (4/8-bit colour is selected by "anchor" sprite) → see tables below %10 = 4-bit colour pattern (128 bytes) using bytes 0..127 of pattern slot, this sprite is "anchor" %11 = 4-bit colour pattern (128 bytes) using bytes 128..255 of pattern slot, this sprite is "anchor"
5	Type for following relative sprites: 0 = "composite", 1 = "big sprite"
4-3	x-axis scale factor: %00 = 1x (16 pixels), %01 = 2x, %10 = 4x, %11 = 8x (128 pixels)
2-1	y-axis scale factor: %00 = 1x (16 pixels), %01 = 2x, %10 = 4x, %11 = 8x (128 pixels)
0	MSB of Y coordinate

For composite relative sprites:

Bit	Description
7-6	%01 = relative sprite
5	"N6" bit, in 4-bit colour mode 0 = using bytes 0..127 of pattern slot, 1 = using bytes 128..255 of pattern slot. In 8-bit mode use 0.
4-3	x-axis scale factor: %00 = 1x (16 pixels), %01 = 2x, %10 = 4x, %11 = 8x (128 pixels)
2-1	y-axis scale factor: %00 = 1x (16 pixels), %01 = 2x, %10 = 4x, %11 = 8x (128 pixels)
0	Enable relative pattern offset (1 = Pattern index is added to anchor pattern index, 0 = independent pattern index)

For big-sprite relative sprites:

Bit	Description
7-6	%01 = relative sprite
5	"N6" bit, in 4-bit colour mode 0 = using bytes 0..127 of pattern slot, 1 = using bytes 128..255 of pattern slot. In 8-bit mode use 0.
4-1	use 0 (scaling is defined by anchor sprite)
0	Enable relative pattern offset (1 = Pattern index is added to anchor pattern index, 0 = independent pattern index)

See Sprite Attribute Upload ($xx57 / 87) for extra notes about anchor/relative sprites, coordinates and clipping.