Watching Contribution (C64)

Over thirty years ago, Contribution by Super Swap Sweden was released and competed in the Rebels and Agile copy party’s demo competition, taking the first place and beating entries from other C64 luminaries including Science 451 and Agile in the process. That probably shouldn’t come as a surprise since the group behind Contribution would soon go on to merge with Thundercats to form Horizon, but this particular release before that merger had a fairly specific impact on me personally which I’ll get to in a couple of paragraphs.

Including the humming intro at the start there are six parts with each showcasing a couple of nifty routines; there’s some “3D” raster bars with a bi-directional, colour split ROL scroller (the latter was the inspiration for my own routine in Koalatro over twenty eight years later), another ROL scroller with some vertical motion – making for some odd but interesting diagonal text whilst being surprisingly hard to explain – running over a thirty two point, bitmap-based plotter, a DYCP scroller which has multiple speed and wave presets, a picture mover using 56 sprites per image together with an eight sprite scroller which both seem to be ignoring the borders and to round things off there’s a pre-calculated logo animation and another sideborder scroller.

I don’t remember having seen a DYCP scroller before this demo so that was doubtless fascinating to me at the time, but what I found to be the most impressive part of the show was seeing the series of ESCOS-style, 56 sprite pictures swinging around the screen and into three of the four borders with the scroller taking up the remaining one. I barely understood what was happening in a regular ESCOS routine or indeed the enhanced ones in things like the NWCUG demos so seeing pictures whizzing around freely like that was sheer magic!

Contribution has a special place in my heart; it was the first Super Swap Sweden demo I ever saw – one of the earliest demos I mail traded with a contact in fact, and it arrived with one of the other entries from the same competition which is on my “to do” list – but that doesn’t change how impressive it was and, in some senses still is. It might seem relatively simple now even if the comparison were to be limited to the developers’ later output, but it still holds together very well and, along with the other Super Swap Sweden demos, is certainly worth watching.

2 thoughts on “Watching Contribution (C64)

  1. Classic demo choice!

    I can’t remember the first thing I saw where sprites went into the side borders, but I remember thinking my C64 was broke or something! Fun times!

  2. I think the first thing I saw was the classic ESCOS demo with Bob’s King Tut picture; that was utterly stunning at the time, the local coders knew how upper and lower borders worked – Jeff Minter had explained it to a friend, he passed it on – but using the sides as well was amazing.

    I also remember taking it to a friend’s place and it not working on his C128 but not finding out until much later why; the video register set-up in ESCOS is handled by a loop which does more than it needs to and writes a non-zero value to $D030 – with the C64 that’s fine, but in the C128’s case it turns on 2MHz mode and sets the VIC-IIe test bit.

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