Emulation continues as long as menu 25 is called. At the end, the screen is drawn to the Spectrum screen buffer, and this is displayed like an image using usual N64 microcode. Each opcode consumes a certain amount of this cycle count. These are set on a per-game basis, but general controls are A/B to start a game, Z for the 'action' button, and L to unload the emulator and return to gameplay.Įach emulation cycle lasts 69888 Spectrum cycles. Necessary buttons to start each game (usually keyboard '0') and any additional keys to play the game are mapped to the keyboard port 254 halfwords. This is mapped as a Kempston joystick on port 31. From there, the monitor program and selected snapshot file are loaded from ROM, and if necessary these files are decompressed. Depending on the button held is which game would be loaded. When initialized, it reads what buttons are held on controller 3. Unlike stages which run by switching to menu 11, the emulator runs by switching to menu 25. Originally, the emulator was run much the same way that stages are run. In its current state, however, the monitor is required. Critical subroutines were copied out or hardcoded. In actual fact, the emulator was supposed to run without the aid of the monitor program. Code Select Expand em/data/ Sabre WulfĮm/data/spec_ Spectrum 16k monitor program
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