Demoscenes

KRYSTAL - SINCLAIR ZX81 16KB MEGA DEMO

With this demo, we would like to pay tribute and remember the 80s, which was a defining era of the rise of domestic IT.

This demo was made in the style we wrote the C64 demos in '91-'92. There are no raster stripes, but we managed to create a giant logo "sprite", running text, and a dancing figure... according to the limited capabilities of the machine.

The basic theme is a mini video clip of a movie, main title/film/cast list. The demo parts are not separated, but come directly one after the other, using a sharp cut or transition effect. By moving the logo and running text, it recalls the style of the 80s. Retro design, mocking today's modern technology, e.g. the smartphone.

The source code consists of 800 lines of assembly, which includes a 1.6 kbyte demo engine and 14 kbyte graphics database, most of which have RLE compression. Only the girl's animation is 32 frames, which is 24576 bytes in uncompressed form. A part of the compressed is continuously decompressed in real time while the demo is running. Only one ROM routine of a couple of bytes is used, that is the key monitor at the beginning, but even with that, it still fits in 16KB.

The graphic part of the demo was completed with the self-developed SINCLAIR ZX81 Screen editor.

After 4 decades, if you still have a working ZX81, you can working circuits a bit with this demo. (download)