Welcome to the WUDSN ursel home page

WUDSN ursel - or short WUDSN - is a demo group founded in 1991. There is an explanation why the group and the site are named like that, but that's a different story you can find in the FAQ. For the time being it should be sufficient for you to know that me, aka JAC! am one of the members ever since. I have created this web site to offer my tools and productions and to share the fun I have had for more than 20 years now with my Atari-8 bit computer and other classic computers. To learn more about me and what I'm doing, check out this personal interview that I gave for ANTIC - the Atari 8-bit podcast.

Atari 2600 - Two new trackers in the making

According to lft, there are 3 approaches for creating music on the Atari VCS

  1. Stick to the very few matching notes, or
  2. Alternate quickly between the very vew matching note, or
  3. ignore the problem.

Given the fact creating music on the Atari VCS nowadays also requires coding skill, the solution is most often option 3. But a few weeks a ago a miracle occurred and suddenly even two trackers for the Atari VCS were released.

Both are very interesting and promising projects and already usable. So get you hands on them, provide feedback to the authors and get something done for Sillyventure. In addition Kylearan held a nice seminar about music and trackers for the VCS at Revision:

"The state of the Atari VCS 2600 music scene is very underdeveloped, despite the fact that it is one of the oldest platforms actively used in the demoscene. In addition to the severe and weird limitations of the hardware itself, there's also a dramatic shortage of tools accessible to musicians. As a consequence, music is hard to come by for a coder, and musical styles are often more uniform and limited than they need to be. In an attempt to improve this situation, we present TIATracker: A new sound routine for the VCS and an accompanying tracker for the PC which tries to support both musicians and coders in dealing with the specific limitations of the platform. This talk will start with a brief recap of the audio capabilities of the VCS. Then, an overview of existing audio routines and tools, both publicly available and proprietary, is provided. This is followed by a discussion and some statistics about how all this might have influenced the culture and quality of music on the VCS. Finally, TIATracker is introduced. It brings ADSR envelopes, variable pattern lengths individual to each channel, funktempo and more to the VCS, and its PC user interface targets non-coder, non-VCS musicians with tools like pitch guides, combined waveform instruments and overlay percussions."

Atari 2600 - I have no memory

The Atari 2600 Video Computer System (VCS) is a unique and interesing thing. The purpose of this tutorial is to show interested people the history of the Atari 2600, explain the hardware design decisions and how they impact the way of programming - making programming the Atari 2600 a very unique experience and challenge. And I show and explain examples that illustrate how programmers adopted the limitations and strengths of the machine to create better and better graphics in the course of 30 years. The following picture from The Argyle Sweater nicely brings it to the point. Thanks a lot to Scott Hilburn for the permission to use it.

Atari VCS has no memory


Heaven's VBXE works - after 6 hours on the CRT battlefield

At Revision in April 2015 Heaven gave me his Atari 130 XE and his Atari 65 XE with VBXE 2.0 installed. The first one had broken down at the party, the second one has a VBXE built in but not adapter cable to connect it to a TV. While the Atari 130 XE worked fine after a little cleaning and re-soldering, the VBXE machine turned out to have an Atari ST monitor connector and a complex switch built in. I sat down for some hours and traced the different signals through all the wires, the switch and the connector. I found that the way the wiring was, the connector can server as FBAS-SCART and RGB- SCART at the same time, depending on the switch position. But I didn't have a proper plug for the connector, so I first had to order one. I had to learn the hard way that there are different types of 8-pin DIN plug with slightly different pin arrangement, none actually fully matches the Atari ST monitor connector.

Months went by and finally I got a working plug, but I was frightened by the thought of soldering SCART cables with 21 pins into the damn tiny DIN plug, no knowing where color meant what and which pin is actually which (plug vs. connector, front-view vs. rear-view, ST plug vs. VBXE pinout, before the switch vs. after the switch....). And guess what: How right I was. 

Today I was in the mood and decided to give it a try. 3 hours of soldering, measuring, desoldering, measuring, re-soldering, dozens of mapping lists and diagrams I finally made it. And then, when the cable was complete, I tested it. And it didn't work at all with my SABA CRT. So a started measuring, desoldering, measuring, re-soldering, checked the diagrams again and again. Then I tried the 2nd CRT (Goldstar). It gave a very dark b/w picture and no VBXE picture at all . The 3rd CRT (Grundig) gave the same result. Meanwhile I was 100% sure that the wiring was fine. CRT number 4 (Schneider) then gave a clear picture with greyscales - in red. IN RED ?!?! Back to the board, did I swap luma with red - no I'm not that stupid. Phew, no, I'm not. The 5th CRT (Sony Triniton) presented a totally distorted picture as it didn't detect that the input was on RGB and not FBAS. Finally I grabbed my (almost) last available CRT: The Phillips that had just left my living room before X-mas. I plugged it in and WHOOOA - it f-cking worked. It just worked and looked perfect. The cable had been correct right from the start, but it took 2 hours to find the TV that could actually handle RGB via SCART. Priceless. Merry Christmas Heaven, you'll get your present soon! Here's how CRT battlefield looked like.

Parnorama view of the CRT battlefield

Working hard on DIS6502

I finally managed to escape the real life daily job business and had a great week with sun, beach and DIS6502.You don't believe that? Check the commits. Again a lot of the monolithic plain C has been transformed into readable classes with clear interaces and dependencies. Now I feel I understand the code good enough to implement the new load/save for the new workspace structure.

Me at the beach bar in Italy