Attribute clash
Several video game consoles of the era had such video modes that caused such limitations, but usually allowed more than two colours per tile: the NES (Famicom) had only one mode, which was also "semigraphic", and allowed four colours per 16×16 "block" (group of four 8×8 tile) but 16 per screen.
The Super NES allowed 16 colours per tile but 256 per screen (among other improvements), and this made the artefact much harder to notice, if at all (except for those who had to program the device).
The Thomson MO5 and TO7 microcomputers, the Oric 1, the MSX 1 architecture, and other systems based on the Texas Instruments TMS9918 video display controller display a very similar constraint: for each group of eight pixels horizontally, only two colours out of 16 are available, giving a similar but less severe effect than with the Spectrum.
Careful design could achieve impressive results, as could synchronising colour changes to the refresh rate of the display—usually a television set.
Thus detailed moving graphics caused large ugly fringes of rapidly changing colours to follow them around.
This also made graphics faster, as less of the screen had to be updated—both a smaller region, plus only changing pixel information and leaving the colour area untouched.
Some Spectrum software, such as FTL's Light Force, used extremely careful graphics design to achieve full-colour moving graphics, essentially by limiting both the design of the onscreen elements and their paths of motion to 8×8 colour resolution boundaries.
Another workaround was to simply render the graphics in two colours, otherwise known as monochrome, as done with the Spectrum version of Knight Lore in 1984.
Many games used this method with smooth pixel-by-pixel scrolling, but the attribute clash as elements of one character block were "passed" to the next were clearly visible.
Programmer Don Priestley developed a distinctive style for several of his games by using large, cartoon-like sprites which were carefully designed to span whole character blocks without appearing unduly square.
Other developers who used a similar technique included Mike Singleton, with Dark Sceptre, and Gang of Five, with Dan Dare: Pilot of the Future.
