Sprite port-mirror Attribute 4 (with INC) Register
| Number | $79 |
|---|---|
| Readable | No |
| Writable | Yes |
| Short Description | Same as Sprite port-mirror Attribute 4 Register ($39) (write fifth byte of sprite-attributes), plus increments Sprite port-mirror Index Register ($34) |
Byte 5 is bitmapped:
| Bit | Description |
|---|---|
| 7 | If 1, the pattern will be treated as 4-bit colour one (128 bytes), 0 is for 8-bit colour patterns (256 bytes) |
| 6 | (if bit 7 = 1): Chooses top/bottom part of pattern slot when 4-bit colour pattern
0 will target bytes 0..127 of pattern "Name" (byte 4), 1 will target bytes 128..255 of pattern "Name". (if bit 7 = 0): make this sprite "relative" one: 1 = relative, 0 = normal (anchor) type |
| 5 | (if bit 7-6 = %01) for "relative" sprite, this bit chooses top/bottom part of pattern slot for 4-bit colour mode (4 or 8 bit mode is set by anchor sprite, relative sprite can't switch the colour mode). See Bit 6 description above, if anchor sprite is in 4-bit mode. If anchor sprite is in 8-bit mode, use always 0
(else) For normal (anchor) sprites this is reserved, use always 0 |
| 4-3 | x-axis scale factor: %00 = 1x (16 pixels), %01 = 2x, %10 = 4x, %11 = 8x (128 pixels) |
| 2-1 | y-axis scale factor: %00 = 1x (16 pixels), %01 = 2x, %10 = 4x, %11 = 8x (128 pixels) |
| 0 | MSB of Y coordinate |
See Sprite Attribute Upload ($xx57 / 87) for extra notes about anchor/relative sprites, coordinates and clipping.
After write into sprite-attribute "byte 5" (Sprite Attribute Upload ($xx57 / 87)), the Sprite port-mirror Index Register ($34) is incremented (with all consequences stemming from such action). If the sprite 127 was modified, the result of the increment is officially "undefined behaviour", and code should explicitly set valid 0..127 sprite index before next sprite-attribute manipulation.