Original GameBoy IPS Mod

A friend gave me two GameBoys, one of which he wanted back after the repair. The other one was dead and I could keep it. So after a quick testing I determined that only the display board was broken due to quite severe battery damage. While maybe salvageable I decided to use a drop in IPS LCD replacement board, as the original DMG screen is pretty abysmal anyway. This mod is relatively easy to install, and requires no soldering!

Upgrading the PET 3016 to 32KB RAM

A couple of years ago I got a PET 3016 from 1979. The machine comes stock with 16KB of RAM and back then we upgraded it using a RAM/ROM expansion, giving it 32KB of SRAM and BASIC V4 ROMs. However it never ran stable in this configuration. It turns out the SRAM was not playing nice with the system. So in this video we will use new old stock 8116 DRAM chips to upgrade the mainboard to its maximum and hopefully get a stable system.


The main issue with the Commodore 8050 and 8250 drives is: How do you get data onto them? The units use 100tpi floppy drives that are incompatible to the regular 48tpi and 96tpi disk drives used in the 1541 and in PC DD and HD drives. So there is no chance using those. However there is the ZoomFloppy, which is an implementation of the XUM1541 interface and it comes with an optional IEE488 plug! We can attach the 8050 to that, and use the OpenCBM tools to read and write data to and from the floppies.

Let’s Code MS DOS 0x24: Low Level Keyboard Programming

Getting input from the keyboard can be as easy as calling the getch() function. But for games we need a better solution. For games on MS DOS machines you need quick, unbuffered input. To simply get the state of keypresses we need to talk to the keyboard controller directly. Let’s have a look at how that’s done!

Let’s Code MS DOS 0x23: 2nd Reality Lens Effect

In 1993 the Future Crew released the seminal demo “Second Reality”. Last episode we re-implemented the tunnel effect, this time we try to understand and replicate the lens effect. A bouncing, tinted glass ball that distorts the background image. Thirty years back it was pretty jaw dropping, and even today we can learn something!

Let’s Code MS DOS 0x22: 2nd Reality Tunnel Effect

In 1993 the Future Crew released the seminal demo “Second Reality”. One of the more simple effects they showed in this demo was the “Dot Tunnel”. It is a simple, yet mesmerizing oldskool demo effect. We can build on our knowledge of fixed point maths to implement this effect and maybe even improve on the original!

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?