16th April 2010In EUG #70, we were blown away by the megademo Retribution X by The Yorkshire Boys. With any luck many of you have checked this out in the meantime and have been similarly impressed. However, Retribution X was not the first disc-based collection of demos for the Beeb, it was just the most professionally put together. For this issue, we've taken a look at one of the older collections of demos, the BBC PD disc Assorted Demos #2, which is (confusingly) the third disc in the BBC PD demos catalogue.
Those out there who are used to my review style will be aware by now that I love demos on the Acorn machines - as long as they are done well. This particular disc is a smattering of all types of demo - some good, some lousy - and, whilst my personal favourites are not necessarily going to be yours, there is no doubt many of the demos here have a more slick feel than others.
Here we go then in order of quality par excellence. Firstly, we have Lars Osterballe's Promote Demo, a scrolling Sphere Of Destiny style landscape which flips back and forth through 180 degrees, also displaying a colourful Mode 5 smooth-scrolling text message as it does so. One can imagine some inspiration was drawn from this little number for the Vector Ball demo produced by The Yorkshire Boys! It also has a tune playing on interrupt throughout!
Next we also have four 'scrollers' by Lars Osterballe, all with their own quirks. Balled Text maps each character onto an invisible 3-dimensional ball and scrolls it up the screen with the illusion of perspective. Overlay Scroll uses machine code to scroll a big message very smoothly from right to left by simply overlaying the graphics spaced four pixels further to the left. Twisted Scroll, an incredibly clever procedure indeed, manages to wrap pixels from the right of each character to the left, and then scroll a message so it appears it is following a looped path. Finally, we have the Waving Sinus demo which shows a vertical 
scroller between two waving 'sinus' bars - this is technically impressive but is probably likely to give you an epileptic fit if you look at it for more than five seconds!!!
Just to finish off the Lars Osterballe collection, there is Screen Waving, a machine code routine that shows how the elements of a picture can be 'displaced'. This is perhaps less interesting to watch - although the half naked warrior pic is a nice touch!
Next we have two 'cluster ball' demos - the first one (Cluster Ball) combines a zippy little four channel tune with a bouncing and spinning ball of stars; the second one dispenses with the tune but, presumably using the Beeb's hardware scrolling, allows you to move the ball around the screen with a joystick. Both are very impressive works and show just how much multi-tasking the machine is capable of.
On then to another two musical megademos. The Dancing Xmas Tree displays a Christmas tree and plays with the hardware controller in time to a drum beat. The effects are a bit odd, with rippling, pixel offsetting, scrolling and occasionally a sort of "pandemonium but with method" display. VU-Meter is a fully machine-coded demo which plays a four channel piece with a vector animation on screen and a graphical display of the sounds emanating from each channel. It's basically a music demo which puts you in charge of the music, allowing you to speed it up, decrease and increase the volume, etc. It's nothing special but good for a few moments' entertainment.
Two more vector demos are on offer too, with a Rotating 3D Box and a Rotating 3D Spaceship allowing you to see what Elite-style objects would move like were they speeded up about 500%. The 3D spaceship is particularly impressive, going randomly on its travels and revolving through different angles as it does so.
The rest of the demos are of the type that you might find in a fanzine rather that 'semi-professional'. The Backwards Screen Demo flips the screen vertically and horizontally, so that pressing BREAK brings up "retupmoC CBB" in the bottom right of the screen and everything scrolls up instead of down. Is this useful? Hmmm, not really, unless you want to freak out a fellow Beeb-owning friend (It survives through a SHIFT-BREAK!). Doomsday Project informs you it is about to tell you the answer to everything in the world and then begins to cycle through every single combination of characters that it can. It's probably been given its name because it will, literally take it until the end of time itself to print out everything.
The ECG Simulation is Chris Richardson's test/game and comes with full instructions. The demo part of it is referable to the different sine waves indicating the state of the patient's (or computer's) heart. The inclusion of a bit of interaction adds to this particular inclusion. Get the type of wave correct to score points.
Life is a version of the game in Mode 7, which we've all seen done better elsewhere. This has a nice demonstration mode, meaning you can sit back and watch life evolve without a lot of effort. The patterns are in fact quite interesting. Parallax Stars scrolls some dots in Mode 0, some dots moving more quickly than others. The stars in this demo move horizontally.
The Computerised Female shows a woman's face and winks and smiles at you. I'm a bit bemused by this demo - it takes four files, only works on the Model B and seems to be of neglible use. I was looking forward to interacting with a female (For once - Ed). Shut up Ed. There is also a demo called Toplady which displays two Mode 0 pictures and flicks between them, presumably to give the appearance of very high resolution. It doesn't quite work under emulation, looking more like a bad animation. On a real BBC it looks reasonably impressive however.
There are some little demos (i.e. just a few kilobytes of code) making up the collection. Curves asks for a faze, X omega and Y omega and then plots a curve. Bezier Curves I have to confess my ignorance of but the random demo plotting them is interesting to watch. Flight Demo (Model B only) is a bit poor, not succeeding in its wish to give the illusion of a view from an aeroplane cockpit travelling at speed. Finally, Duncan Lilly's Zarch Imitator draws the landscapes popularised by the Archimedes game Zarch; random hills in perspective from random angles.
Because many of these demos require a large number of files, the disc is double-sided and packed full of them. Unfortunately, few of them work on the Electron, but there's a lot to entertain a BBC owner even with my very short attention span. However, if you do want to have a look at what's on offer, you might, in absence of the AEW DVD, actually have some difficulty tracking this particular disc down. It does not exist in this format anywhere else in cyberspace.
