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TEA1002

From Wikipedia, the free encyclopedia

The TEA1002 is a PAL video encoder chip[1] produced by Mullard in 1982 and used on the Mattel Aquarius computer and AlphaTantel Prestel adapter.[2][3][4][5] It was also used on teletext decoders and color bar generators associated with video test equipment.[6][7]

The chip is capable of displaying 40 × 24 text blocks with 8 × 8 pixel characters, corresponding a theoretical resolution of 320 × 192 pixels (within borders), with the character set allowing for a 80 × 72 semigraphics display. Correction update - this chip does not generate the display itself, its only a colour encoder.

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

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According to the TEA1002 datasheet,[1] colors are formed by the combination of three signals, roughly equivalent to the HSL colorspace:

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 75% 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)[1]
Color R G B INV Luminance (%) Chroma (º) Chroma (%)
Black 0 0 0 0 0.0 - -
Red 1 0 0 0 22.5 103 48
Green 0 1 0 0 44.0 241 44
Yellow 1 1 0 0 66.5 167 33
Blue 0 0 1 0 8.5 347 33
Magenta 1 0 1 0 31.0 61 44
Cyan 0 1 1 0 52.5 283 48
White 1 1 1 0 100.0 - -
Grey 0 0 0 1 75.0 - -
Cyan 1 0 0 1 52.5 283 24
Magenta 0 1 0 1 31.0 61 22
Blue 1 1 0 1 8.5 347 17
Yellow 0 0 1 1 66.5 167 17
Green 1 0 0 1 44.0 241 22
Red 0 1 1 1 22.5 103 24
Black 1 1 1 1 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.[1]

TEA1002 Logic inputs and composite video output (configured for 95% BBC colour bars)[1]
Color R G B INV Luminance (%) Chroma (º) Chroma (%)
Black 0 0 0 0 0.0 - -
Red 1 0 0 0 47.5 103 48
Green 0 1 0 0 69 241 44
Yellow 1 1 0 0 91.5 167 33
Blue 0 0 1 0 33.5 347 33
Magenta 1 0 0 0 56 61 44
Cyan 0 1 1 0 77.5 283 48
White 1 1 1 0 100.0 - -
Grey 0 0 0 1 100.0 - -
Cyan 1 0 0 1 77.5 283 24
Magenta 0 1 0 1 56 61 22
Blue 1 1 0 1 33.5 347 17
Yellow 0 0 1 1 91.5 167 17
Green 1 0 0 1 69 241 22
Red 0 1 1 1 47.5 103 24
Black 1 1 1 1 0.0 - -

See also

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References

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  1. ^ a b c d e TEA1002 PAL Colour Encoder and Video Summer. Mullard. 1982.
  2. ^ "Machine: Mullard TEA1002 PAL colour encoder (tea1002)". Vas the Man’s Arcade.
  3. ^ Graham, Adrian. "AlphaTantel Viewdata Terminal". Binary Dinosaurs. Retrieved 2023-05-02.
  4. ^ Graham, Adrian. "AlphaTantel Viewdata Terminal Motherboard". Binary Dinosaurs.
  5. ^ "Machine: AlphaTantel (alphatan)". Vas the Man’s Arcade.
  6. ^ Jenkins, Tony (June 1984). "TV Test Pattern Generator" (PDF). Television. p. 436.
  7. ^ "TEA1002 PAL COLOUR ENCODER AND VIDEO SUMMER". Fabian Enterprises. 2013.