When an emulator window is not the active (focused) window, the emulator is usually suspended until its window becomes active again. If you have a sufficiently fast Mac it is recommended that you use CPU Cycle exact Mode, otherwise you should use High Precision or Advanced Timing. Unfortunately this precision does again increase the load on the Mac CPU. This can be necessary for very special tricks (like Electronic Arts Fastloader). In particular the VIC now steals the correct cycles from the CPU (rather than just the (almost) correct number as in High Precision Mode). CPU Cycle Exact Mode works like High Precision Mode with respect to the VIC, but does a more exact timing analysis for the CPU. These features come at the cost of increased stress on the Mac CPU. It is therefore the most compatible type of video emulation, and the only mode that is able to simulate features like open left/right borders, or changes in the background color in the middle of a scanline. High Precision Mode takes care of all changes in the video registers that occur during the duration of a scanline. ![]() In contrast to this Advanced Timing mode obtains the Sprite information at the beginning of the scanline, and draws the rest of the image approximately in the middle. In Scanline mode (which is fastest) the entire scanline is drawn at once at the beginning of the scanline. Power64 currently supports five types of video emulation, that differ in respect to the exact timing of video image calculation. To display the actual number of frames per second enable the menu item Options/Display CPU Load (see below). Only games that require very precise Sprite Collision detection might require Frames per Computed Screen to be set to 1:1. Thus Auto is the recommended setting for both Frames per Computed Screen and Frames per Screen Redraw. Choosing Auto causes Power64 to select the speed that best fits the C64 game and Macintosh used. 1:n indicates that the screen is redone only on every n-th frame. A setting of 1:1 means that the screen is recomputed/redraw 50(PAL) or 60(NTSC) times a second. Frames per Screen Redraw sets the frequency of the second step. Frames per Computed Screen defines how often the first step is performed. This image is compared to the one last computed and only if a change is detected then the changed parts are copied to the Macintosh screen in a second step. In a first step it creates an image of the C64 screen in an internal buffer (as a byproduct of this computation Power64 also checks for sprite collisions). Power64 maintains the screen in two steps. Note so, that compatibility for games will suffer if you select a value different from 100%.įrames per Computed Screen & Frames per Screen Redraw: If you have a CPU intensive program, that you want executed as fast as possible, than this is the parameter to adjust. In addition to adjustments to the System Clock it is also possible to accelerate the CPU alone. Note that compatibility will still suffer if you select a value different from 100%. You can increase the System Clock rate to obtain a faster C64 while maintaining the speed ratio between CPU and CIA. This frequency is used to drive the CPU and CIAs (Timers) (but not the SID or VIC). Only games that won't work in PAL mode should be run in NTSC mode.ĭepending on the choice of video mode the reference clock of the emulated C64 is driven at either 0.985MHz (PAL) or 1.023MHz (NTSC). ![]() PAL mode produces less strain on the Mac CPU and is therefore advantageous. Most C64-programs will work fine in both modes. Depending on the video mode the internal clock of the C64 is driven at either 0.985MHz (=625*63*50/2 PAL) or 1.023MHz (=525*65*60/2 NTSC). ![]() Furthermore both half images are then same, resulting in stretched image in vertical direction. To make a full TV signal all pixels are displayed at half the regular TV pixel rate, with the effect, that they are scaled in horizontal direction. Around this area there is a frame, that stretches the image to about (depending on the actual TV set connected) 384x288(PAL) pixels. The central image of a C64 screen has a resolution of 320x200 pixels. When a Commodore 64 is connected to the TV the standards are interpreted in a slightly different manner. ![]() during each screen refresh, only every other scanline gets redrawn, thus the entire image is only redrawn at 25Hz (PAL) or 30Hz (NTSC). Note that both systems use interleaving, i.e. NTSC on the other hand uses only 525 that are redisplayed at 60Hz. A PAL signal consists of 625 scanlines (including scanlines for vertical blank, leaving a usable resolution of 768x576 pixels) that are displayed at a nominal refresh rate of 50Hz. While PAL used in most west European countries (except France), NTSC is the common standard in North America. PAL and NTSC are two major standards for television signals. The speed of the Emulator can be controlled using the menu item Options/Emulator Speed.
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