We’ve got another piece of C64 scene history today, the Mean Team’s VSP&IK+ from 1987. This is another of those demos from the “Wild West” period when programmers were as much concerned if not more so with getting their latest creations out there and the name is pretty much self-explanatory; the IK+ part comes from the music by Rob Hubbard and Paul “Dokk” Docherty picture which were both being taken from the game of the same name, whilst the VSP refers to it being the first instance of Variable Screen Positioning, a hardware “feature” similar to but much harder to implement than the more common Flexible Line Distancing – FLD to its friends – which was in common use around that time.
This technique is sometimes referred to as DMA delay because that’s essentially how it works, waiting for a badline where the C64 fetches screen data and fooling the VIC-II into waiting for a fixed amount of cycles before that fetch actually takes place by setting the vertical scroll register to a value that won’t see it happen, then changing back to one where it will later in the line. One cycle equates to the width of a character so waiting five cycles will push the screen right by that many characters and it’s possible to travel an entire screen width, with the data wrapping around onto the start of the next line, something this demo masks by changing the attribute data. VSP-based scrolling is how games like Mayhem In Monsterland can move their backgrounds so quickly.
I remember seeing VSP&IK+ for the first time on a friend’s C64, casually thinking “oh that’s nice and smooth” in passing as it started up and the picture slid smoothly in from right to left and then staring in disbelief as it snapped back in the other direction at far too great a speed to merely be a double buffered bitmap scroller – we already knew about FLD and understood how it worked but this was nothing short of witchcraft at the time! It still makes me smile now despite knowing how the routine works and having my own examples.
Let’s do something a little different and look at one of my own demos, specifically Demo Factory on the C64 from 1987. The original idea came about from a brainstorming session with friends and was intended to be a less than serious response to the plethora of bog standard demos around at the time which usually included a bitmapped picture, some music and a sprite-based ROL scroller in the border. We all found the idea of an automated factory churning these similar-looking demos out on a conveyor belt amusing so I set about programming, pausing only to work things out on paper first – something I haven’t bothered doing since – and to read up on how the hardware sprite priority registers worked from the C64 Programmer’s Reference Guide.
Looking back now the code itself is embarrassingly simple – even more so than I remembered it being in fact – but in my defence I was still learning assembly language and indeed the C64 at the time. The music is Rob Hubbard’s Hunter Patrol theme which arrived as a file he’d uploaded to Compunet that had the music located low in memory and started an IRQ to play it before dropping back to BASIC; my code calls that and executes behind it, using timing loops rather than actually waiting for a rasterline or anything sensible because I didn’t know better. I’m tempted to call this my first “real demo” because, despite there being a few releases prior to it including Past Shock, this was the first time I managed to get action on the screen with someone else’s music playing.
The “logic” was, if I recall correctly after three decades, that a parody didn’t have to be particularly well programmed because shonky code could be passed off as part of the joke; similarly, the lack of a scrolling message was absolutely part of the “protest” against bog standard demos and not in the slightest because I couldn’t get one working or anything like that… honest! There’s also a healthy whiff of irony and very probably hypocrisy about me of all people railing against the bog standard demo as a format since I’m incredibly fond of it as a format, was inspired to start coding demos by releases like Future Shock and have since programmed several releases over the years which stick to that tried and tested formula.
I’ve considered doing a remixed version of Demo Factory on a couple of occasions previously which would be an overhaul of the graphics and actually running from interrupt with all the benefits that would entail; it could perhaps animate all of the elements of the demo making machine that I wasn’t able to handle back in 1987 as well and, just for the sake of irony, would probably include a scrolling message as well…?
I’ve previously mentioned The Exceptions’ early Atari ST demos in passing when talking about Demons Are Forever on the Amiga and was… well, a little less than charitable about them. The first one was Readme.prg – it may have had other names but that seems to be the consensus now – which came out in March of 1987 and was essentially a “bog standard” picture, scroller and music demo of the variety that C64 owners had been seeing since the previous year.
Visually, there’s a very nicely drawn and very colourful picture with the focal point being a dragon clutching the TEX logo and torching a boing ball with its breath, a not-so-subtle dig at the Amiga and there’s another in the parallax scrolling message. Sound was pulled from the Holger Gehrmann game Extensor – there’s a couple of pieces in there and one is very noticeably his style, but I found that changing tunes would sometimes break things so only did so sparingly whilst recording – which are nice but, to my mind at least, don’t really fit with the graphics.
In 1987 we were all waiting on truly staggering things from these incoming 16-bit systems which at least some of the game developers were struggling to deliver on, so a scrolling message with a picture didn’t really sit well next to those expectations; yes the graphics were of a better quality than we were used to from the 8-bits but that’s what the next generation of hardware is supposed to bring to the table and, whilst the music is reasonable, it didn’t really scream “bleeding edge sound” either, being more reminiscent of the Amstrad CPC or AY-equipped Spectrum than anything else.
I’m aware that sounds rather harsh because it probably is all things considered, but these write ups aren’t reviews so tend to be coloured by my personal preferences and indeed emotions; putting on my rather fetching objective hat for a moment, I know that Readme.prg represents a hugely important scene milestone as one of the very first demos released on the Atari ST – possibly even the first scene-produced production in fact – so should be lauded for that and it’s a reasonably solid production for what it is, especially if you leave it running with tune 1 playing as I’ve done whilst writing.