Paratech
April 28th, 2010, 15:30
Haze Update (http://mamedev.emulab.it/haze/)
Making a Killing, Killing a Dragon
One of the most common questions I get asked is ‘Why is the PGM hardware so badly emulated?’
The answer to this is simple, it isn’t. The actual PGM emulation (aside from the sound chip) is mostly complete. The problem is that every single PGM game has it’s own protection scheme, and the later ones (which is the real reason people complain) are very, very well protected, and are IMPOSSIBLE to emulate properly without expensive hardware decapping because even with trojans you can’t read out all the internal ROM code. (So don’t ask about them)
With that said some of the older ones still present interesting challenges to study. The Killing Blade has been emulated for a long time, but it’s always bothered me that in order for it to run a dump of the RAM content from a running machine was required to bypass proper emulation of a scrambled DMA device. A few days ago XingXing sent me some data from tests he did on the PCB, allowing me to properly implement the transfers and remove the fake ROM. This means that both sets of The Killing Blade now work correctly (previously only the parent set worked, because the RAM dump was incorrect for the clone).
http://mamedev.emulab.it/haze/news2010/killbld_0000.png
Making a Killing, Killing a Dragon
One of the most common questions I get asked is ‘Why is the PGM hardware so badly emulated?’
The answer to this is simple, it isn’t. The actual PGM emulation (aside from the sound chip) is mostly complete. The problem is that every single PGM game has it’s own protection scheme, and the later ones (which is the real reason people complain) are very, very well protected, and are IMPOSSIBLE to emulate properly without expensive hardware decapping because even with trojans you can’t read out all the internal ROM code. (So don’t ask about them)
With that said some of the older ones still present interesting challenges to study. The Killing Blade has been emulated for a long time, but it’s always bothered me that in order for it to run a dump of the RAM content from a running machine was required to bypass proper emulation of a scrambled DMA device. A few days ago XingXing sent me some data from tests he did on the PCB, allowing me to properly implement the transfers and remove the fake ROM. This means that both sets of The Killing Blade now work correctly (previously only the parent set worked, because the RAM dump was incorrect for the clone).
http://mamedev.emulab.it/haze/news2010/killbld_0000.png