FPGA VGA Card specifications

Description

The card features VGA output at 640x480 resolution.

This is only a preliminary specification and is subject to change during the development of the VGA card.

Display mode overview

Text mode

The text mode has a maximum of a 80 x 30 character display. Each character can be assigned some basic attributes. The text window can also be set to be displayed at different positions on the screen and the width and height of the display window varied. The text can also be display over the top of bitmap and patten modes.

Bitmap mode

The bitmap mode can work in both a native resolution of 640x480 or a half resolution size of 320x240. Each mode can be display is 4, 8 and 12-bit color with the 4 and 8 bit modes controlled by a palette. Bitmap size is independent of the screen size and limited by available VRAM. Hardware horizontal and vertical scrolling is available around the entire bitmap. Sprites can be displayed over the bitmap, see the sprites section for more information

Tile mode

The Tile mode can work in both the native and half resolution modes in the same fashion as the bitmap mode. Each mode can have a single or double layer of tiles where each tile are 16x16 pixel with a color depth of 8bpp. Each tile layer can be controlled independently and has a separate palette of 256 (255 + 1 transparent) colors. Each tile layer can select from up to 1024 tiles from a map size of 256x256 tiles. Sprites can be along with the tiles and can be displayed above or below the tiles depending on priority, see the sprites section for more information.