Posts: dots tunnel
- Dots tunnel: a 256 × 256 screen and 400 dots
What if the CPC screen changed shape so that the address of a dot were quicker to compute? The dots tunnel moves to a square screen, then spends the time saved on more dots.
- Dots tunnel: the stack, the registers and unrolling
Where do the NOPs of a dots tunnel dot go, instruction by instruction, and how many can the Z80 stack, its registers and unrolling remove without changing a single picture?
- Dots tunnel: two screens, and clearing only the dots
The v1 of the dots tunnel clears 16 KB per picture for 256 lit bytes at most, and its picture flickers. Two versions in Z80 fix the flicker, then the clearing, and we measure what each one brings.
- Dots tunnel: from the tables to a first Z80 tunnel
How the CPC stores its pixels in memory, the dots tunnel tables computed in Locomotive BASIC then by RASM, byte for byte, and a first, slow version of the tunnel in Z80, whose time we measure picture by picture.
- Dots tunnel: the principle, explained in JavaScript
Building a dots tunnel one idea at a time, in JavaScript, on a simulated CPC screen: from the projection of a circle to the byte tables the Z80 expects.