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This series of talks and workshops will introduce to the world of demo programming on the Atari ST platform.

Your host: User:Gunstick

Talk about this on the discussion section of this page

For the moment chip tunes are not covered in all this. They will be used but not explained in detail how it works. You need to be a musician and programmer to dive into that. As that is mainly audio stuff the best place to do this will be a radio show ChiptuneHistory

You don't need to follow all talks and workshops as some will be overlapping and repeats.

The presentation method will be using the Gunstick-has-all-in-his-head technique. The workshops will be using real Atari hardware and emulators.


please register on this page if you are interested in anything of this so you get emails for announcements

workshop prerequisites

(this section needs links to the different items, for now just use google and luck)

To fully get up to speed with the workshop you need a working ST or emulator. There are several emulators of various quality available. Best of course is to get your hands on a real ST.

Using the real hardware brings of course some logistics problems: those things run on RGB tv frequency, and that's quite difficult to get today's LCDs to understand. So you need desk space to set up a CRT and the ST with various cables.

Using emulators has limitations as the hardware tricks are not always well emulated. Best emulator is Saint. Unfortunately only available on windows (no idea if it works with vmware fusion or wine). Another OK alternative is Steem Engine or hatari. For the emulator you also need a copy of the OS which I can give to you (hint, there's a working linux steem installation on the laptop in the chill).

And finally some software is needed. Real hardware likes floppies, the SD kind. HD do not really work well. The emulators use disk images which can be downloaded from many sites.

We will use one type of software: the assembler. There are 2 available. Devpac, a classic macro assembler. And Turboass, no macros but blazing fast (i.e. instant assembly).

Workshop 1: Introduction

  • Introduction to the Atari ST
    • History
    • presentation of the hardware
    • the OS and available software
  • evolution of software
    • games
    • cracks
    • demos
  • fist steps
    • start your ST (or emulator)
    • get programs and stuff
    • run software

Workshop 2: ST Hacking

Hacking the Atari ST

  • hardware modifications
    • add ram
    • add realtime clock
    • add screen size
  • overcoming hardware limitations with software
    • scrolling
    • distorter
    • digisound
    • sprites
    • colors
    • higher resolution
    • scrolling way too much
    • lines, faces and 3D

Workshop 3: putting it all together

  • The impossible demo: parallax distorter (from minute 08:30). People always thought that on the ST
    • you can't do 500 colors at once -> colorshok demo
    • you can't play digital samples -> digit demo
    • the video signal has always a border around -> overscan demo
    • it's impossible to move the whole screen contents -> syncscroll demo
    • bitwise shifting is impossible -> distorter
    • playfields are an Amiga thing -> playfield demo
    • there are no sprites on the ST -> big sprite demo
  • but of course this demo shows all this, at the same time (which is also impossible)
    • the algorithmic theory behind it
    • how to integrate all the effects into one
    • showing off devpac and turboass
    • visually inspecting synchon code

Workshop 4: assembler and hardware

  • programming the 68000 in assembler (using turboass)
  • specificity of the Atari ST hardware
  • smooth scrolling howto
  • color cycling effects
  • tricking the ST hardware in other ways

Workshop 5: algorythm optimizations and beyond

  • algorithms in theory
  • and in practice
  • and even faster
  • faster than experts think
  • the CLF technique (i.e. the impossible part)

Workshop 6: synchron programming in practice

  • diving into the internals of the impossible demo
  • source code
  • change parameters and watch results

Workshop 7: type your own code

  • design your own demo
  • can it be done?
  • program it!
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