He starts at the top left of the screen, looks in the first screen memory location and discovers which colour he should be painting the first pixel. Imagine there's a little imp, whose job it is to paint whatever is in the Spectrum's memory onto your TV. How does ULAplus work and how do you get 256 colours on screen at once? Synthesized, so I don't know how big a CPLD/FPGA is required." - Chris Smith. Worse case, a small amount ofĮxternal memory may be required, or FPGA is used instead, as this will The two-levels-of-intensity effect and the edge-artifact with flashingĪs devices are much larger and efficient these days, it is likely toįit into a reasonably cheap CPLD. Have been the major issue, leading to other colour effects similar to Memory would have been required for the palette. The 5C000 ULA had 440 matrix cells in total, so you'd needĪt least two ULAs of that size.
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That would take 832 matrix cells of the ULA, plus the other necessaryĬircuitry. Gates for the multiplexing (4*16*8 + 16*8 ). 64 * 8įlip-Flop/latches for the palette storage = 512, plus a 640 2-input-nor It would take ".gazillions of gates and flip-flops. Yes, but more than one ULA would have been required and it would have been much more complicated and therefore expensive. Switching between the 64-colour mode and the standard mode gives you an additional four colours (BRIGHT 0/FLASH 0 INKs 1, 3, 5, and 7) which are not present in the standard palette for a total of 260 colours on screen.Ĭould Sinclair have done this back in the day? Changing the palette while the screen is drawing enables you to have 256 colours on screen at once. How many colours can I have on screen at once?Ī static screen using no CPU time can have 64 colours on screen at once. There's the palette editor and a 6-bit RGB palette for Artist III with more in development. Set some colours before turning on 64-colour mode. The hardware can't set the palette registers by itself.
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