The ReSeed SID Sound Card for the Plus/4 & C16

The Commodore 264 machines, which include the Plus/4 and the C16 used the TED chip for video and sound. The audio capabilities were not great: two square wave channels. The Commodore 64’s SID chip on the other hand was a proper three voice synthesizer. So back in the day people built expansion cartridges for the Plus/4 utilizing the SID and eventually games and demos using this were published. These cards are pretty rare, but now there is a homebrew clone of the card!

Let’s Code MS DOS 0x21: 3D Fixed Point Maths

The 3D Wireframe cube is part of every demoscene coder’s learning curve. Today I want to talk you through the principles of 3D programming in general and especially the idea of fixed point maths, where you use integers instead of floating point numbers to represent fractions. Older CPUs before the 80486 had no built in floating point support, and even the FPUs were quite often rather slow and hard to program for, if available at all. So people had to opt to use integer arithmetics in stead. But 3D graphics requires fractional numbers, so how do we get both things together and manage to display a rotating wireframe cube on our MS DOS machine?