In the previous post I mentioned at the end that the BIOS, running on the ATMega328p, was only capable of communication one way. There are a couple of mailbox memory locations that are used to pass keystrokes to the 8-bit CPUs (Z80 or 6502), yet no way of receiving data back, other than an acknowledgement that the keystroke has been processed. In order to make the BIOS a bit more BASIC-friendly, I needed to add …
One of the demos I’ve carried across nearly all the platforms I’ve worked on is the rotating cube demo, typically with back-face culling (hidden line/face removal), perspective, and fast integer maths. The code has been ported to the Gameboy, CPC, PC, Atari ST and Scratch. On more capable systems I usually add filled-in polygons with simple texture mapping and Gouraud shading I first wrote this demo around 30-odd years ago for the Spectrum, and I …
I’ve been using the ZXSpin emulator for a while now to develop code on the ZX Spectrum. This has many advantages, namely an integrated assembler and disassembler, but quite a few quirks, and the editor, whilst adequate for small projects, is not really up to scratch for large ones. In addition, my main machine is an old Macbook, so have to boot into Windows on it to do any software development. My criteria for the …
