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!

Let’s Code MS DOS 0x17: Come On Let’s Twist

One ubiquitous demo effect that can be seen on a wide variety of demos and intros is the twister or the twister bar. There are numerous examples in productions for the Amiga, Atari ST and 2600 that I know of (and even at least one on the Sega Master System). And probably a lot more that I don’t know. However I have never seen this effect in any of the old PC demos, except maybe in Future Crew’s PANIC, where something very similar was used for the vertical scrolling greetings. But it was not quite the same still. So today we will code a variant of the twister using Turbo C for MS DOS!

Retro Burner: Refurbishing and Retrobriting the Galep III

I got an old Galep-III universal EPROM programmer from a friend. He couldn’t get the device to work under Windows 10, since it is quite old and uses the parallel port. This device is perfect for my 486! And since I just finished assembling an XT CF Lite card, I needed something to write its EEPROM with.
The device looks a bit aged, due to dirt and severe yellowing, so we will clean it and retrobrite it, to make it look like new. This is only my second attempt (after an experiment with my serial mouse), so let’s hope for the best!

Let’s Code ESP8266: The SI7021 Temperature and Humidity Sensor

The SiliconLabs SI7021 is a very popular sensor for measuring temperature and humidity. It uses the I2C bus and is easily accessed from the ESP9266 or ESP32. Some breakout boards use different variants of the chip, namely the measurement Specialties HTU21D or even the Sensirion SHT21. These chips are more or less compatible to one another, but some don’t implement all the commands. However temperature and humidity can be used on all those chips. Today I’ll walk you through a tutorial of accessing the SI7021 via the Arduino Wire library.

Upgrading The VGA RAMDAC

The VGA cards for historic PCs have an analog video output that is being driven by a so called RAMDAC. This is an IC that converts the digital framebuffer information into analog VGA signals. Modern PCs don’t need this anymore since they use digital output (like HDMI and DisplayPort) and digital displays. But our old retro machines use this to drive either an LCD or a traditional CRT. There are good RAMDACs out there and bad ones. One problem some RAMDACs have is noise when the VGA palette registers are written. This happens in games and demos for example when the screen is fading in or out. I found a supplier of new old stock INMOS RAMDACs, and I hope that replacing the cheap ADV RAMDAC on my Tseng ET4000 will remove the noise that I am seeing.