The TEA1002 is a PAL video encoder chip produced by Mullard in 1982 and used on the Mattel Aquarius computer, the AlphaTantel Prestel adapter and the Microvector 256 color graphics display interface for Nascom and Gemini computers. It was also used on teletext decoders and color bar generators associated with video test equipment.
It generates 16 colors based on Luminance, Chrominance and Saturation, usually with the 8 basic colors being similar to the EBU 75% color bars.
Levels According to the TEA1002 datasheet, colors are formed by the combination of three signals, roughly equivalent to the HSL colorspace:
Luminance Chroma phase (º, equivalent to hue angle) Chroma amplitude (%, equivalent to saturation)
Internally colors are stored in a 4-bit RGBI arrangement. There are three bits for the RGB components (generating 8 primary colors at full saturation but 75% luminance - similar to the EBU colour bars) and an inverter logic input bit that controls a variation of the base color (a 25% Luminance decrease for white; a 50% Chroma saturation decrease for all colors).
The following table lists the internal signals and shows an approximation of the generated colors, as seen on a web standard sRGB monitor. Colors could be different when seen on an analog PAL CRT television.
+TEA1002 Logic inputs and composite video output (configured for 75% EBU colour bars) Color RGBINV Luminance (%) Chroma (º) Chroma (%) Black0000 0.0 - -Red1000 22.5 103 ±48Green0100 44.0 241 ±44Yellow1100 66.5 167 ±33Blue0010 8.5 347 ±33Magenta1010 31.0 61 ±44Cyan0110 52.5 283 ±48White1110 100.0 - -Grey0001 75.0 - -Cyan1001 52.5 283 ±24Magenta0101 31.0 61 ±22Blue1101 8.5 347 ±17Yellow0011 66.5 167 ±17Green1001 44.0 241 ±22Red0111 22.5 103 ±24Black1111 0.0 - -
An alternate configuration of the chip allows it to output 95% luminance color bars - similar to BBC colour bars, more suited for usage in teletext decoders.
+TEA1002 Logic inputs and composite video output (configured for 95% BBC colour bars) Color RGBINV Luminance (%) Chroma (º) Chroma (%) Black0000 0.0 - -Red1000 47.5 103 ±48Green0100 69 241 ±44Yellow1100 91.5 167 ±33Blue0010 33.5 347 ±33Magenta1000 56 61 ±44Cyan0110 77.5 283 ±48White1110 100.0 - -Grey0001 100.0 - -Cyan1001 77.5 283 ±24Magenta0101 56 61 ±22Blue1101 33.5 347 ±17Yellow0011 91.5 167 ±17Green1001 69 241 ±22Red0111 47.5 103 ±24Black1111 0.0 - -
See also Thomson EF9345 Motorola 6845 TMS9918 MOS Technology VIC-II List of home computers by video hardware
References