Is the One Chip MSX a real MSX or not?

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Par multi

Expert (74)

Portrait de multi

13-02-2007, 21:35

Imagine that I used a *feature* of the original MSX, such as the 5th sprite rule. This pure MSX program will not work in a *fixed* OCM with no 5th sprite rule.

using a feature like a 5th sprite rule? what are you going to do then? monitor the 5th sprite to implement some kind of hacked line interrupt? if this is what you are talking about then i can't see how this is something in the MSX standard, since the standard did not specify when the 5th sprite detection was done and when the result was placed in the register. it only states that it is done at some undefined moment in time.

so if you are talking about a hacked VHDL version that does not implement the 5th sprite, no one would blame you if the code relied on hiding sprites by putting 5 in a row and it would look odd. if the other one was the case you just did not make a "pure MSX" program.

this is what TI says about their chip, and they even do not guarentee anything on timing: www.xs4all.nl/~ronholst/map/resources/video/texasinstruments_tms9918.pdf

Par Manuel

Ascended (18794)

Portrait de Manuel

13-02-2007, 22:56

E.g. The Maze of Galious uses the 5th sprite rule to mask off the sprite when entering a shrine. It will break on a "fixed" machine.

Par poke-1,170

Paragon (1768)

Portrait de poke-1,170

14-02-2007, 00:28

I wonder if it's so bad that things aren't downward compatible...Not everyone can run turbo r games if you don't have one.
Not everyone can play msx 2 games if you don't have an msx2. PLus I guess there are more OCM's around then turbo r's.
having a gfx9000 and moonsound shows that there could be done even more with an msx then the real ones could.
Those 2 additions have been embraced with open arms.
So why not the OCM ?
I agree with latok that it's the msx-a and nishi who decide what msx is, give it corporate identity etc.
When windows releases vista, do you still run 98 or ME ?
If they decide they release a new piece of hardware, and they decide that doing it like this is efficient,
then that's the standard. Like it or not, I think they have a bit more authority then anyone else here.
If sony says the PS3 is a playstation, then it is a playstation, even if the hardware is completely different.
Is the WII not a WII because you can run non nintendo related games on it as well ?
It's nice seeing that people know better what an msx is then nishii, I guess he'll be quite surprised hearing
that the thing he relased, his new baby, is in fact not an msx.

Par multi

Expert (74)

Portrait de multi

14-02-2007, 00:31

E.g. The Maze of Galious uses the 5th sprite rule to mask off the sprite when entering a shrine. It will break on a "fixed" machine.

wow, didn't know that. nice example!

and here i thought you couldn't use that silly 5th sprite for anything useful oO

Par dvik

Prophet (2200)

Portrait de dvik

14-02-2007, 02:18

@wolf_: Have you had a chance to listen to an OCM yet? I'm a bit curious how good the audio is emulated. I think the OCM has potential to sound better than an old MSX since you don't have any interference with power, floppies and other things that makes a real MSX a bit noisy. But it requires of course that the emulation itself is well done and I haven't seen any comments on it.

Par poke-1,170

Paragon (1768)

Portrait de poke-1,170

14-02-2007, 05:36

I heard it, over a big PA haha... there should be a youtube link roaming around here somewhere demonstrating it

Par wolf_

Ambassador_ (9956)

Portrait de wolf_

14-02-2007, 10:12

dvik: nope, I would've had the opportunity at several MSXCG meetings if some Dutch reviewsite had returned the OCM the past few months..

As for emulators : they currently aren't good enough. One of the essential things missing in FM emulation are legato envelopes, which means that tones with a certain attack are, like, 'smoothed' together to sound more as one line.. bit hard to explain perhaps.. but quickly after a note with that same envelope a new attack doesn't start from volume 0 afaik but somewhere halfway. There are quite some musicdisks that go horribly wrong because of this. I don't know exact specs about this, you'll have to try to find docs about this.

Par wolf_

Ambassador_ (9956)

Portrait de wolf_

14-02-2007, 10:53

Also, the only annoying thing for me is humm/buzz noise from the electrical net. As for noise: this can actually make the sound more alive. This noise, of course, is something one could control manually..

Par dvik

Prophet (2200)

Portrait de dvik

14-02-2007, 14:23

The reason why I am a bit, well I shouldn't say worried, but maybe concerned about the audio in the OCM is the fact that PC emus aren't very accurate. I would think that the OCM implementation is based on some exisiting PC emulation. But there are quite a few FM implementtaions and hopefully the OCM is one of the better.

That particular bug you're talking about doesn't sound too hard to fix but maybe there is more to it. I'll see if there is something I can do. Is there a particular OPL that has the problem or all of them?

Par wolf_

Ambassador_ (9956)

Portrait de wolf_

14-02-2007, 14:38

I dunno if is to be called a bug, I'd rather call it lack of functionality. In which case there's nothing to bug hunt for, it's just another thing to implement.
Note however that I haven't been using BlueMSX for ages, ever since its interface runs like a snail and it messes up my 98 system when I'm low on resources (it messes up my mIRC buttons, panels etc. for instance). So I don't know exactly whether this legato functionality applies to BlueMSX as well. When was that lite edition of BlueMSX to be scheduled again? (the one without the resource hogs)

Anway, to check on this functionality: grab Moonblaster orso, make a sound with a long attack and long release, and play some notes with it in a single pattern channel. You'll surely notice the legato effect.

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