Attribute clash
display artefact caused by limits in the graphics circuitry of a some colour 8-bit home computers, most notably the Sinclair ZX Spectrum, where it meant that only two colours could be used in any 8×8 tile of pixels
Attribute clash (also known as colour clash or bleeding) is a display artifact caused by limits in the graphics circuitry of some colour 8-bit home computers, most notably the ZX Spectrum, where it meant that only two colours could be used in any 8×8 tile of pixels. The effect was also noticeable on MSX software and in some Commodore 64 titles. There are workarounds to prevent this limit from becoming apparent.
Causes
Attribute clash on the ZX Spectrum was caused by its idiosyncratic display memory layout, designed in such a way as to minimise memory use of the frame buffer, and optimise for text display instead of graphics. Rather than limit the colour palette to conserve memory, Sinclair's design stored pixel bitmap and colour information in separate areas of memory. While the bitmap specified the state of individual pixels (either on or off), the colour information (or "attributes") corresponded to the text character matrix—24 rows of 32 columns—with one byte per 8×8 pixel character cell. This byte encoded two 3-bit values, known as INK (foreground colour) and PAPER (background colour) after the BASIC instructions used to define the colour values. Two other binary values were included in an attribute; a BRIGHT bit indicating one of two brightness levels for the two colours, and a FLASH bit, which, when set, caused the two colours to be swapped at regular intervals. This scheme provided 15 different colours: the eight combinations of red, green and blue at two brightness levels (except for black, which appeared the same at both brightness). Thus, each 8×8 pixel block could only contain 2 colours from the 15 available, which must both be from either the BRIGHT or non-BRIGHT halves of the palette.
“Attribute clash” enters the record as display artefact caused by limits in the graphics circuitry of a some colour 8-bit home computers, most notably the Sinclair ZX Spectrum, where it meant that only two colours could be used in any 8×8 tile of pixels. Crown Archives preserves that source wording while asking what Attribute, clash and display can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated May 6, 2026. The linked authority identifier is Q4231817. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Attribute clash” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.