Most of it is already being taken by the platform, hence why Exodus requires more processing power than most (all?) other Mega Drive emulators out there. Exodus has a design that aims to minimize that cost, but it will be there. If you want to respond to bus requests accurately within 2 cycles, you need to be checking at 3,805,000 points during execution of your 68000 core for bus access requests each second, and more than that, you need to keep your cores "in sync" so that you don't find out about an access attempt after you've already passed the time when it should have been processed. There is an unavoidable performance hit in doing this. There are several challenges in overcoming this barrier. Both are incorrect, and can easily impact timing sensitive code. Most other emulators only synchronise between cores and check for access requests at fixed points, usually thousands of cycles in length. Right now, Exodus only checks between opcodes, meaning most bus ownership requests are delayed. This means there are around 3,805,000 timing points each second where external requests to obtain the bus need to be checked and responded to in order to get perfect timing accuracy. The real 68000 processor will respond to bus requests within 2 cycles, or if it's currently actively performing a bus operation itself, at the end of the current bus cycle (4 cycles typically, but can be longer). Here's the kicker - the 68000 processor can release the bus to share with other devices, such as for DMA operations from the VDP, or banked memory access from the Z80. A single opcode usually takes between 4 and 40 of those cycles to execute, but it can be a lot more than that for MOVEM opcodes, and potentially hundreds for multiply and divide operations.
The 68000 processor in the Mega Drive is clocked at around 7.61Mhz, meaning 7,610,000 cycles per second. Right now I'm trying to break through a barrier to cycle accurate emulation that no software emulator has done to date.
Repeat this process for each button in the list.I'm going to start using this news feed as a development blog, to keep people updated with what's happening with upcoming changes, and how development is going in general. To do this, ensure your controller is connected to your PC before launching ares, then simply go to the ‘Settings -> Input’ menu and double click a to map in the ares window, then press the button on your controller you would like to map. You will however need to set up your controller upon first launching ares before you game play a game. To load the save state, go to the ‘Tools -> Load State’ menu and select the required save state slot to recall.Īres works with pretty much any Windows-compatible controller that you have connected to your PC. Save & Load States – To save games and reload their save state, go to the ‘Tools -> Save State’ menu and pick a save state slot.Shader Effects – Go to the ‘Settings -> Shader’ menu and select the shader you wish ares to apply.Change Video Scaling – Go to the ‘Settings -> Output’ menu and select the required video scaling mode.Full-Screen Mode – Go to the ‘Settings -> Hotkeys’ menu and assign a key to the ‘Toggle Fullscreen’ option, then use that key to switch between windowed and full-screen mode.Increase Game Window Size – Go to the ‘Settings -> Size’ menu and select the screen size multiplier required.Launching Games – Go to the ‘Load -> Sega -> Mega Drive’ menu and simply select your game, it will then automatically launch.Here are some tips for using ares to play Sega Genesis games on PC. But that would just be overlooking the fantastic features ares has to offer. The great thing about ares is that it really doesn’t require any setting up if you’re just looking to launch a Genesis game and be on your way.