2
Specifications
The following table sums up the main features and characteristics of Zeal Video Board:
| Features | Details | Description |
|---|---|---|
| Video | Resolutions | 640x480, 320x240 |
| Color depth | 16-bit, RGB565 | |
| Memory | 128KB of mapped memory (check Memory Mapping) | |
| Video RAM | ~80KB of internal memory, no need for external RAM! | |
| 64KB tileset RAM, enough for 256 tiles in 8bpp, 512 tiles in 4bpp | ||
| 1KB sprites RAM, composed of 128 sprites | ||
| 6,400 bytes tilemap RAM, representing a grid of 80x40 tiles | ||
| 512 bytes palette RAM, composed of 256 16-bit colors | ||
| Text mode | 80x40 characters, wrapped when scrolled 40x20 characters, showing hidden characters when scrolled |
|
| 16 colors per character, for both foreground and background, taken from the global palette | ||
| 8x12px per character | ||
| Font Table of 256 characters, 12 bytes per characters, customizable at runtime | ||
| Hardware cursor, scroll, wait-on-newline support | ||
| Graphics mode | Virtual resolution of 1280x640, only 640x480 or 320x240 can be visible at once | |
| Hardware scrolling | ||
| Color palette (RGB565 colors) usable as a single 256-color palette or 16x16-color palettes Palette customizable at runtime |
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| 16x16px tiles, 8bpp or 4bpp | ||
| 640x480px resolution, 40x30 tiles visible on screen 320x240px resolution, 20x15 tiles visible on screen |
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| Up to 256 different tiles on screen at the same time in 8bpp mode (256-color palette) Up to 512 different tiles on screen at the same time in 4bpp mode (16 16-color palette) |
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| One background layer, one foreground layer with transparency in 8bpp mode Single layer in 4bpp mode, support flip X and flip Y |
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| Sprites | 128 hardware sprites, up to 40 sprites per scanline | |
| 16x16px tiles, taken from the same tileset than the other layers | ||
| Flip X and flip Y supported | ||
| Can be hidden behind foreground layer in 8bpp mode | ||
| Can be partially hidden in the screen borders | ||
| Bitmap modes | 320x200 or 256x240 resolutions | |
| 8bpp, using the global paletter | ||
| Configurable border color | ||
| Scrollable view | ||
| Audio | PSG | 4 voices |
| Each voice can generate triangle waves, sawtooth waves, squares waves or noise | ||
| Sample table | 256-byte sample table to generate arbitrary sound | |
| Configurable sample rate | ||
| SPI | TF Card | Interface up to 25MHz, configurable |
| Hardware FIFO | ||
| Timer | Timer | Hardware timer controller |
| 16-bit divider | ||
| 16-bit counter | ||
| count up or down | ||
| Auto-reload from preset | ||
| Accelerator | DMA | Hardware DMA controller |
| 24-bit physical address descriptor | ||
| Configurable inc/dec/none operations for both source and destination addresses | ||
| Configurable wait states for read and write | ||
| Checksum | CRC32 | Hardware CRC32 controller |
| No wait state | ||
| Miscellaneous | Recovery mode, to be able to upgrade the firmware from the 8-bit computer | |
| Modular memory mapping thanks to configuration registers | ||
| Hardware v-blank interrupt line | ||
| Hardware general purpose interrupt line (unused for now) |