VICKY

VICKY - the graphics engine

"Vicky" is the name of the graphics engine of the C256 Foenix. It supports:

• 640x480@60FPS Max Resolution @ 256 Colors (1 Byte per pixel)
• 32 Sprites with a resolution of 32x32 pixels
• 4 layers of tiles with a resolution of 16x16 pixels for each tile
• Text Mode

During the video layer composition, Vicky has to read 1 line of bitmap (640 pixels), 1 line of tiles for each layer (4x 640 pixels) and all the lines that are part of the 32 Sprites (worst case scenario 32 lines of 32 pixels), that are displayed on that line. Then a composition and priority encoding is done. In order to establish a priority, in other words, to know which pixel will be in front, Vicky needs to store 10 lines of 640 pixels then scan the lot and determine which one will be displayed.

640 + 640 + 640 + 640 + 640 + (32 * 32) = 4224 Pixels are to be read during a single line interval. The pixel rate is 200Mbytes/sec, 5ns, so the overall operation takes 21.12us, without calculating the overhead in the FPGA to go from one process to the other.

The pixel index value $00 is always transparent, regardless if it's bitmap, tile or sprite. The respective values of the first 4 bytes represented in the LUT are thus always ignored.

Despite the fact that there is an ALPHA value in the LUT, it is not supported/used at all.

Vicky Gloabl Memory Map:

Start Address	Stop Address	Register Description	Additional Info
$AF:0000	$AF:0000	MASTER_CTRL_REG_L	Vicky Master Control Registers
$AF:0001	$AF:0001	MASTER_CTRL_REG_H
$AF:0002	$AF:0002	VKY_RESERVED_00
$AF:0003	$AF:0003	VKY_RESERVED_01
$AF:0004	$AF:0004	BORDER_CTRL_REG	Border Control Registers
$AF:0005	$AF:0005	BORDER_COLOR_B
$AF:0006	$AF:0006	BORDER_COLOR_G
$AF:0007	$AF:0007	BORDER_COLOR_R
$AF:0008	$AF:0008	BACKGROUND_COLOR_B	Background Control Registers
$AF:0009	$AF:0009	BACKGROUND_COLOR_G
$AF:000A	$AF:000A	BACKGROUND_COLOR_R
$AF:000B	$AF:000F	UNDEFINED - RESERVED
$AF:0010	$AF:0010	VKY_TXT_CURSOR_CTRL_REG	Cursor Control Registers
$AF:0011	$AF:0011	VKY_TXT_RESERVED
$AF:0012	$AF:0012	VKY_TXT_CURSOR_CHAR_REG	Char used as the Cursor
$AF:0013	$AF:0013	VKY_TXT_CURSOR_COLR_REG	Color Choice for the Cursor
$AF:0014	$AF:0014	VKY_TXT_CURSOR_X_REG_L	Cursor Position X
$AF:0015	$AF:0015	VKY_TXT_CURSOR_X_REG_H
$AF:0016	$AF:0016	VKY_TXT_CURSOR_Y_REG_L	Cursor Position Y
$AF:0017	$AF:0017	VKY_TXT_CURSOR_Y_REG_H
$AF:0018	$AF:001B	UNDEFINED - RESERVED
$AF:001C	$AF:001C	VKY_INFO_CHIP_NUM_L	Vicky Chip Part Number
$AF:001D	$AF:001D	VKY_INFO_CHIP_NUM_H
$AF:001E	$AF:001E	VKY_INFO_CHIP_VER_L	Vicky Chip Version
$AF:001F	$AF:001F	VKY_INFO_CHIP_VER_H
$AF:0020	$AF:00FF	UNDEFINED - RESERVED
$AF:0100	$AF:0100	TL0_CONTROL_REG	Tile 0 Register Set
$AF:0101	$AF:0101	TL0_START_ADDY_L	Start Address Within the Video Memory
$AF:0102	$AF:0102	TL0_START_ADDY_M
$AF:0103	$AF:0103	TL0_START_ADDY_H
$AF:0104	$AF:0104	TL0_SCROLL_X
$AF:0105	$AF:0105	TL0_SCROLL_Y
$AF:0106	$AF:0107	UNDEFINED - RESERVED
$AF:0108	$AF:0108	TL1_CONTROL_REG	Tile 1 Register Set
$AF:0109	$AF:0109	TL1_START_ADDY_L	Start Address Within the Video Memory
$AF:010A	$AF:010A	TL1_START_ADDY_M
$AF:010B	$AF:010B	TL1_START_ADDY_H
$AF:010C	$AF:010C	TL1_SCROLL_X
$AF:010D	$AF:010D	TL1_SCROLL_Y
$AF:010E	$AF:010F	UNDEFINED - RESERVED
$AF:0110	$AF:0110	TL2_CONTROL_REG	Tile 2 Register Set
$AF:0111	$AF:0111	TL2_START_ADDY_L	Start Address Within the Video Memory
$AF:0112	$AF:0112	TL2_START_ADDY_M
$AF:0113	$AF:0113	TL2_START_ADDY_H
$AF:0114	$AF:0114	TL2_SCROLL_X
$AF:0115	$AF:0115	TL2_SCROLL_Y
$AF:0116	$AF:0117	UNDEFINED - RESERVED
$AF:0118	$AF:0118	TL3_CONTROL_REG	Tile 3 Register Set
$AF:0119	$AF:0119	TL3_START_ADDY_L	Start Address Within the Video Memory
$AF:011A	$AF:011A	TL3_START_ADDY_M
$AF:011B	$AF:011B	TL3_START_ADDY_H
$AF:011C	$AF:011C	TL3_SCROLL_X
$AF:011D	$AF:011D	TL3_SCROLL_Y
$AF:011E	$AF:011F	UNDEFINED - RESERVED
$AF:0120	$AF:013F	UNDEFINED - RESERVED
$AF:0140	$AF:0140	BM_CONTROL_REG	Bitmap Registers Set
$AF:0141	$AF:0141	BM_START_ADDY_L	Start Address Within the Video Memory
$AF:0142	$AF:0142	BM_START_ADDY_M
$AF:0143	$AF:0143	BM_START_ADDY_H
$AF:0144	$AF:0144	BM_X_SIZE_L	Needs to be set to 640
$AF:0145	$AF:0145	BM_X_SIZE_H
$AF:0146	$AF:0146	BM_Y_SIZE_L	Needs to be set to 480
$AF:0147	$AF:0147	BM_Y_SIZE_H
$AF:0148	$AF:014F	BM_RESERVED
$AF:0150	$AF:01FF	UNDEFINED - RESERVED
$AF:0200	$AF:0200	SP00_CONTROL_REG	Sprite 0 (Highest Priority)
$AF:0201	$AF:0201	SP00_ADDY_PTR_L	Start Address Within the Video Memory
$AF:0202	$AF:0202	SP00_ADDY_PTR_M
$AF:0203	$AF:0203	SP00_ADDY_PTR_H
$AF:0204	$AF:0204	SP00_X_POS_L
$AF:0205	$AF:0205	SP00_X_POS_H
$AF:0206	$AF:0206	SP00_Y_POS_L
$AF:0207	$AF:0207	SP00_Y_POS_H
$AF:0208	$AF:020F		SP01 - Sprite 1
$AF:0210	$AF:0217		SP02 - Sprite 2
$AF:0218	$AF:021F		SP03 - Sprite 3
$AF:0220	$AF:0227		SP04 - Sprite 4
$AF:0228	$AF:022F		SP05 - Sprite 5
$AF:0230	$AF:0237		SP06 - Sprite 6
$AF:0238	$AF:023F		SP07 - Sprite 7
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1
$AF:0208	$AF:020F	SP01 - Sprite 1

Modes

Modes are enabled and disabled via the Vicky Master Control Register at $AF0000 via the control bits:

Mstr_Ctrl_Text_Mode_En	= $01	Enable the Text Mode
Mstr_Ctrl_Text_Overlay	= $02	Enable the Overlay of the text mode on top of Graphic Mode (the Background Color is ignored)
Mstr_Ctrl_Graph_Mode_En	= $04	Enable the Graphic Mode
Mstr_Ctrl_Bitmap_En	= $08	Enable the Bitmap Module In Vicky
Mstr_Ctrl_TileMap_En	= $10	Enable the Tile Module in Vicky
Mstr_Ctrl_Sprite_En	= $20	Enable the Sprite Module in Vicky
Mstr_Ctrl_GAMMA_En	= $40	Enable the GAMMA correction - The Analog and DVI have different color values, the GAMMA is great to correct the difference
Mstr_Ctrl_Disable_Vid	= $80	This will disable the Scanning of the Video information in the 4Meg of VideoRAM hence giving 100% bandwidth to the CPU

Bitmap Layer

The bitmap is stored anywhere in $B0 bank memory. If the bitmap is supposed to start at $B0:0000, the BM_START_ADDY has to be set to $00:0000.

• BM_CONTROL_REG = $AF0140
  • Bit 0 = disable/enable
  • Bit 1-3 = Target LUT address located at AF:2000 and up.
• BM_START_ADDY_L = $AF0141
• BM_START_ADDY_M = $AF0142
• BM_START_ADDY_H = $AF0143

LUT

A LUT, namely a Look-Up-Table, stores a selection of colors. 256 colors are supported in the video composition, which are selectable out of 16.777.216 colors in the 24 Bit RGB color scheme. The LUT also contains an 8 Bit alpha channel, though it isn't supported. In summary, the LUT has $400 (1024) bytes - and the order for composing it is B -> G -> R -> A.

As an example, if you would want to compose a LUT of 16 base colors, it would look like this:

Address	Hex Values (BGRA)	Decimal RGB Value
$AF:2000	-- ignored --	-- ignored --
$AF:2004	00 00 00 00	0, 0, 0
$AF:2008	FF FF FF 00	255, 255, 255
$AF:200C	00 00 88 00	0, 0, 136
$AF:2010	EE FF AA 00	238, 255, 170
$AF:2014	CC 44 CC 00	204, 68, 204
$AF:2018	55 CC 00 00	85, 204, 0
$AF:201C	AA 00 00 00	170, 0, 0
$AF:2020	77 EE EE 00	119, 238, 238
$AF:2024	55 88 DD 00	85, 136, 221
$AF:2028	00 44 66 00	0, 68, 102
$AF:202C	77 77 FF 00	119, 119, 255
$AF:2030	33 33 33 00	51, 51, 51
$AF:2034	77 77 77 00	119, 119, 119
$AF:2038	66 FF AA 00	102, 255, 170
$AF:203C	FF 88 00 00	255, 136, 0
$AF:2040	BB BB BB 00	187, 187, 187

Adressing anything in the LUT is achieved by simply dividing the lower 10 bits of target color address by 4.