Let’s Code MS DOS 0x1B: Fixed Point Arithmetics Rotozoomer

In the last episode we learned how to code the rotozoom effect using floating point arithmetics. This however is pretty slow on ancient DOS machines, like 486 and even worse on slower machines. So in this episode we will rewrite the program to use integer based fixed point arithmetics.

Let’s Code MS DOS 0x1A: I Am Not An Atomic Playboy! (The Rotozoomer)

Back in 1993 the Future Crew published „Second Reality“ on the PC. This was a mega-demo of epic proportions. It showcases many new and some old effects with a brilliant soundtrack. One of the effects that was very well done and that stuck in my mind was the „rotozoomer“. A tiling image being rotated and scaled in a very fluent animation. As a kid I wondered how it’s done. Later I learned the maths behind this and today we want to explore this simple yet brilliant effect. In this part we will deal with the basics and implement a floating point version. However the original code used fixed point integer arithmetics, which we will visit in a second video…

C64 Repair: Bad Color RAM

We already had a C64G on the channel, which was working fine, but was missing some keys and came „only“ with a SwinSID. This time we get a regular brown breadbin C64 with a fault: It’s showing flickery colors. This might be due to two things: Either the 1K color SRAM or the PLA might be broken. One way to find out: open up and replace some chips!

The Queen of Soundcards: Roland LAPC I

The Roland MT-32 and its brethren CM-32 and CM64 were external MIDI synthesizers that were very much a gold standard for MS DOS gaming. There was one more obscure device though, which was compatible for the most part, namely the LAPC-I. It was a CM-32 and a MPU-401 rolled into one. It’s a big whopping 8-bit ISA card. Today we will have a close look and listen to some samples.

Let’s Code MS DOS 0x18: VGA Plasma

The plasma is a staple of the demo scene effects. You can find it on all platforms: PC, C64, Amiga, Atari… So why don’t we code one ourselves? We base our program on the Fire effect done in an earlier episode, so if you missed that, please check it out, too. We simply replace the draw function with an appropriate algorithm for drawing… the plasma! It’s actually pretty simple.

The TTL Graveyard Clock

The 74 series of ICs is one of the longest running IC series. They encompass all basic logic functions and more. It is (almost) possible to build basically any digital circuit from chips of this series, without needing to use a micro controller. However it quickly becomes expensive as the transistor density of those chips is not very high. But they are a great way to learn about transistor-transistor-logic, or TTL. Today we’ll build the „TTL Graveyard Clock“, named as such because it… looks a bit like a graveyard, and this is also where 74 series chips go to die…? Kidding aside, this clock is an impressive design by Sergey Kiselev and a great way to learn soldering as well as to learn how 74 series ICs work. Plus in the end you get a fully functioning 24 hour clock with seconds!

The Greaseweazle: Inexpensive Rescue of Old Floppies

There are many solutions to image old floppies on a very low, flux based level: Kryoflux, Catweasel, Fluxengine or Supercard Pro, to name a few. The Greaseweazle is a low cost, open source variant that can be had for less than 10 EUR. It is suitable to generate disk images of a wide variety of formats, including but not limited to IBM PC, Atari ST, C64 and Amiga. In this video you can see me test the device and create a pipeline for more or less easy creation of different disk images. In theory you can even salvage data off of damaged disks. This heavily depends on how much of the disk is still readable though, and you should weigh your options carefully if the data in question is really valuable, of course.

Playing Game Music without a PC: The Roland SB55

Roland produced a number of SoundCanvas and related products. The SoundCanvas 55 came with an optional device called the SoundBrush 55. This was a floppy based MIDI recorder and player. Musicians could use it to either play back MIDI files or alternatively to record their performances. We will of course use the device to play back video game music without the need of a PC! I will have a look inside this device, which is well over 25 years old and also will hook it up to my SC55 and the MT32.

Pimping the C64

A good friend of the channel by the name of matze79 supplied me with a rather cheap C64G. As I didn’t own a C64 at the moment, this was an excellent opportunity. The poort little C64 came with two missing keys, which were fixed by 3D printed replacements. While this looks interesting and is impressive in its own right, I wanted a more long lasting fix. The C64 was also missing its SID chip and came with a nice little SwinSID. But again, we have some better replacement on hand! So let’s open up the machine, fix those things and enjoy the fantastic world of programs the C64 has to offer!