This project is an envisioning of an alternate universe mid-80s home computer. It runs on RP2350 boards, with the Adafruit Fruit Jam as the primary target. The name is an homage to the VIC-II chip at the core of the Commodore 64 computer.
It is primarily written in symbolasm, a modern syntax for ARM assembly language.
A roadmap is coming soon.
Beam racing
In the early 80s, there were two camps regarding video output: a dumb framebuffer and more sophisticated on-the-fly video processing. Rendering tiles and sprites on the fly was ideally suited to 8 bit video games, enabling smoothly interactive graphics without much effort by the CPU.
Text modes were in some ways a special case of on the fly rendering. Invariably limited to fixed-width cells, video RAM contained character indices and additional attributes, and during a scanline the video hardware would look up the character index in a font RAM before scanning out. This mechanism actually has a lot in common with video game tile rendering, and C64 games often abused the text rendering capabilities to draw game content.
The heart of vic-2350 is a beam racing renderer, inspired by 80s hardware. The RP2350 has a rare confluence of factors that make beam racing appealing: framebuffers take too much RAM (so the resolution and color depth is limited), plus the chip has enough horsepower to render quite interesting graphics on the fly.
This project is a continuation of pico-dvi-rs, with a much greater emphasis on bare metal programming.
Building
The build needs:
- Rust, with the
thumbv8m.main-none-eabihftarget - symbolasm, checked out next to this repo as
../symbolasm - The
arm-none-eabibinutils (onlyasandldare used) - Python 3
Then ./build.sh builds each demo into build/<demo>.elf. Set SYMBOLASM to use a symbolasm checkout somewhere else.
The RP2350 register definitions come from the rp235x-pac crate, which the build fetches along with the other Rust dependencies. Set SVD to use a different RP2350.svd.
Running
Put the board in BOOTSEL mode, then run, for example:
picotool -x build/colorbars.elf
You can also use tools/run.sh, which, in addition to picotool, prints logs sent over USB serial. It can also start from an existing running demo, using the "1200 bps touch" method.
Demos
colorbars
This just demonstrates a simple bringup of video out, and can also be useful for calibrating video capture.
console
(no screenshot)
Displays raw USB reports; useful for debugging mice, keyboards, and other devices.
image
Displays an image encoded using the nibnib image compression format. The image is stored in flash. It should be 640x480.
rects & drag
The rects demo displays 64 colored rectangles bouncing around, showing off the animation capabilities of the race-the-beam renderer. There is also a drag variant that lets you drag the rectangles around with a USB mouse. That demo also shows off sprite rendering capabilities, for the mouse cursor.
sd_video
Plays a video clip from the SD card. The screenshot above is from Big Buck Bunny by the Blender Foundation (licensed as CC-BY 3.0). Copy the encoded video to VIDEO.NIB in the root of the SD card.
The re-encoded video binary can be found in the v0.1.0 release assets.
textdemo
A demo of text rendering. It's a proportionally spaced font (helvR10.bdf from adobe-100dpi from the xorg distribution). One line scrolls, showing basic animation.
tiles
A demo of 16x16 tile rendering, 16 colors each, with multiple palettes. The tileset is by Dandelion Pixel Art; see the maps/ subdirectory for more info.
License
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.