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Core Dump

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Core Dump - Work In Progress

Episode 61

April 1, 1998 : Sound trick that might cause some problems

Exams, exams... this way a home-grown coder can't work. And then, when the exams are over, it turns out that the summer has been showing its first rays - so one is obliged to go out and have fun and drink stuff in the sun (in Maastricht, for example). How can one finish a game this way?

You can't. But still, I've been adding quite a few new zones, and had a go at getting the music right. Added a new weapon. And I modified the swimming stuff.

Before this week, when you didn't have a "swim suit", you simply couldn't dive. Pressing down when floating didn't do anything. But that wasn't very realistic, so I changed it. You can now always dive, but if you haven't got the swim suit, you'll lose energy as time goes by. (Accompanied by a nice "alarming" sound) It's much more fun to play this way, to see how far you can get...

Enemy A.I. continued to create problems especially now that it is being linked to the difficulty settings. But what is completed now is working as expected. Still, I am sure that the way I am doing it now is the easiest way. But using an MSX to coordinate 20 enemies through variable terrain with many parameters is just asking for trouble - one of the few games that could be compared with Core Dump speed-wise is Fantasm Soldier IV, but that engine only covers on-screen enemies, and even they have simple movement patterns. Core Dump on the other hand keeps track of all the enemies on the map. But it has to, because there might be a camera pointing at a landmine or something at an arbitrary point on the map. So an enemy that is at that point has to be moving, or else it looks pretty silly. In other games you could just "switch off" enemies that are not on-screen.

FM-PAC music trick

Something has been worrying me though.

When composing FM-PAC music, I use a trick. Not in the books. Oh dear - you can feel the incompatibility problems looking around the corner.

What's the trick? Well, FM-PAC sound generation is a process with two halves- first there are some parameters used at startup, and then there are only a few parameters that are used further on in the sound. You can exploit this. You can even try it in BASIC, I believe, using the AUDREG command. If anyone knows the exact syntax. What you do is this: you start plaing a tone with any given instrument. Now, after a short time you manually alter the instrument (using register changes) while the tone can still be heard. So, just change the instrument number register but leave the KEY ON/OFF settings the way they are. What happens is that you get a new sound. So, setting a "FLUTE" (standard sound) while playing a "VIOLIN" results in (sort of) white noise! I've been using this trick since "Black Cyclon" and it has served me many times, because lack of instruments is the main FM-PAC problem. (Yes, it also works with FM-PAK because they use the same Yamaha chip.)

But now - and I haven't tested it yet - there are these emulators. And there is no way to predict how it'll sound on a different chip, because this behaviour was not even in the original specification of the FM sound chip. If anyone spots a difference, let me know.

Go on...

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