question about CHD games, need help

[the3eyedblindman]

I was going to stick a dreamcast in my cab for games like blitz and showtime, but its just not the real thing, but i also heard chd games like blitz dont run well on computers, i have an amd athlon xp 2000, which is like 1.6 ghz i think. Will chds run on here, and well? and do any of you have nfl blitz or nba showtime on your cabs ( mainly those 2, but others too)?

[RacerX]

Blitz won't be playable on it, and I figure Showtime would be the same.  I have an AMD XP1800 processor that I run Area 51 on, though.  It's not quite at full speed, but it runs pretty well.  So it isn't necessarily all CHD games that won't run well.

For Blitz I just use the PC version.  It can be found on Ebay fairly often for a very cheap price.  I got mine for about $5.00, and that was a year ago.  I've seen them go for a lot less lately.  The PC version is pretty darn accurate, but there is no cursing (which isn't necessarily a bad thing).  

[the3eyedblindman]

I was also told that the processors used to run nfl blitz in arcades were not even as fast as an amd xp 2000, so i dont understand....?

[Hooch]

I'm running an AMD-2500+ overclocked to 3200 and it still doesn't run blitz at a playable speed.  I'm assuming the amd-64 FX-53 is getting close to emulating it at a playable speed, with some tweaks.  The reasons why it won't run at full speed for a while is many, but the main reason is because the processor is being asked to emulate all the parts of the arcade machine, whereas the processor in the arcade cabinet itself doesn't have as much to do.  One other factor would be mame itself, it's possible that some of the contributors to the project may find some ways to speed up the drivers in the future.  Anyway, that's my .02.  I'm sure there are others who know much more than me about this that can pipe in.

[NoOne=NBA=]

That is why the one that is MADE for the PC runs fine.

The problem you run into with any emulation is that the computer is running its own OS, and then running a program that has to run the actual commands from the ROM in question.
This results in the computer spending the majority of its time "interpretting" things, which doesn't let it use its full potential to "process" things.

A good analogy of this would be two people, (one from China, and the other from the US) who didn't know a translator who spoke both languages using their own translators who both knew French.

Imagine the extra time/energy needed for an English-French-Chinese-French-English conversation, vs. an English-English one.
Emulation is ROM-Emulator-Computer-Emulator-ROM, vs. ROM-Processor.

[the3eyedblindman]

Well what are some of the chds that run fine, and which ones dont?

[MiKman]

As Hooch said there are many reasons mame and other platform emulators run slowly but one of the main reasons is that you are in essence generating code from the instructions from the ROM image that can be run natively on your computer.  It's like NoOne=NBA= said you are not just running a program that was made for your intel PC. You are running a program that has nothing to do with windows or intel and cannot run on windows at all.  So it needs to be interpretted first then converted and new code generated that will run on your PC and all this takes processing horsepower and is done 'on the fly' so to speak, so it all slows things down.  And sometimes this whole interpretation routine isn't very clean.  Mame, I'm sure, is as clean as it can get with the experts we have working on it :-). Sometimes it takes dozens of instructions to duplicate the function of a single original instruction for the Arcade game you are emulating.  Crappy explanation I know but it's the best I can come up with...