Table of Contents
Some short notes of how I envision the audio/video of NeoCore to be.
This means that the following might, and most likely will, change aT anytime.
Video
Resolution
To find an optimal base resolution is a struggle. There is alot of parameters to consider.
After some thinking I opted for the 640 x 480 in 4:3 as a reasonable compromise, and 640 x 360 in 16:9. This would be supperior for the era, but not crazy so. It is also compatible with the Commander X16 in 4:3.
Bitplanes, modes and colors
The Comodore machines redefined the normal character set for custom graphics. That is a bit to restricted. The CPU is a bit to slow to really use a full bitmaped display, so some form of tiling is needed.
There should be a way to use either pure text, tiles, photos or bitmaps. Text in 2 colors, and tiles should have 1, 2, 4 or 8 bitplanes, for 2, 4, 16 or 256 colors. The same goes for full bitmap.
One color should be reserved for transparancy. With a selectable bottom color.
There should also be a possibility to use multiple and overlaid modes with different scrolling in X and Y direction. Atleast 4 seams a good number.
All modes should have defineable start in X/Y and Width/Height. This lowers memory requirements for stationary information such as score, lives etc in games.
On top of this we also have 256 sprites with different Z-priority.
Tiles
They should have a standard size of 8 x 8, 16 x 16, 24 x 24 and 32 x 32.
Text
We also want to have a seperate text mode with changable fonts.
- The text should have different textcolors and background colors.
- There should be a option for reverse, underline and flashing.
- There should be support for umlauts and descenders. So a 12 x 16 cell, 8 x 12 or similair would be good.
Photos
The FPGA also renderes photos encoded in JPG. This can be for photos, background or cut-away scenes. With sub 40ms rendering also video should be doable.
Bitmap
Bitmaps is also drawn in 1, 2, 4 or 8 bitplanes.
Sprites
They should have a standard size of 8 x 8, 16 x 16, 24 x 24 and 32 x 32. Colors are 2, 16 and 256.
Palette
The Palette is 4bits per color, 12 bits, or 4096 colors.
Audio
Audio should come from 8 sound generators, with left, right or both outputs. Waveforms are sinus, square, sawtooth, triangle and noise or a combination. Frequency and pulse width can be set. The volume uses a standard ADSR (Attack, Decay, Sustain, and Release) mode, with an overall volume controll.
There will also be 4 channels of wavetable 8-bit PCM sound. Again routed to left, right or both outputs.
There will be no extra on-board soundchips. Mostly due to that candidates are hard and/or expensive to source. However, all the expansion pods have Audio input.