|link| - Bad Apple C64

You might ask: Of all the videos, why this one?

This is the secret sauce. The 1541 drive has a CPU of its own (a 6502, same as the C64!). Sam realized that by programming the drive’s CPU to read raw GCR (Group Code Recording) data and send it to the C64 via a fastloader routine, they could achieve a sustained transfer rate of ~8-10 kilobits per second. They interleaved the video data on the disk so that by the time the C64 finished decoding one frame, the drive had the next sector already spinning under the head.

While the original shadow video is black and white, the C64 version uses the machine’s native luminance. They chose a dark grey (Color $0B) and a bright white (Color $01) on a black background. This reduces color data to zero—each pixel is simply "on" or "off." This allows them to use without wasting bytes on color attributes.

The key breakthrough was realizing that storing pixel data (bitmaps) was a dead end. Instead, the demo relies on vector graphics. In the original "Bad Apple!!" music video, the black silhouettes are essentially shapes. If you can describe the mathematical outlines of those shapes, you can store them much more efficiently than storing every single pixel. bad apple c64

The "Bad Apple" shadow video is a brutal stress test. It is not a loop. It is 3 minutes and 39 seconds of continuous, high-contrast animation featuring dozens of Touhou characters (Reimu, Marisa, Sakuya) morphing, swinging weapons, and moving through complex parallax-like backgrounds. Each frame is unique.

Let’s put "Bad Apple C64" into perspective.

Porting a high-frame-rate video to a 1 MHz machine with only 64KB of RAM is a nightmare. The original video contains over 6,000 frames. On a standard C64, a single uncompressed frame could take up 8KB or more—meaning the entire video would require dozens of floppy disks. How Onslaught Cracked the Code In 2014, the demo group Bad Apple 64 You might ask: Of all the videos, why this one

Purists were not satisfied. They wanted a standard C64 with a standard 1541 drive.

To watch Bad Apple on a Commodore 64 is to confront the ghost of computing past. You realize that the hardware limits we complain about today—battery life, thermal throttling, VRAM—are luxuries. The C64 has none. It has a flickering CRT, a screaming disk drive, and a SID chip that runs so hot you can burn your finger on it.

Each frame’s shape (a girl’s hair, a falling apple, a rotating umbrella) was encoded as a series of line endpoints. The playback routine then the frame on the fly using fast line-drawing code. This reduced data per frame from 8,000 bytes to sometimes just 50–200 bytes. Sam realized that by programming the drive’s CPU

The shadow video features large, contiguous black areas. Instead of storing each pixel, the C64 stores instructions: "52 white pixels, then 200 black pixels." By analyzing the frames and encoding them as differentials (only the changes from the previous frame), the data per frame crashes from 8,000 bytes to as few as 200-300 bytes.

Your modern PC will yawn at 4K YouTube. But your soul? It will cheer every dropped frame of a 40-year-old computer doing the impossible.