The TEA1002 is a PAL video encoder chip1 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.23456 It was also used on teletext decoders and color bar generators associated with video test equipment.78
It generates 16 colors based on Luminance, Chrominance and Saturation, usually with the 8 basic colors being similar to the EBU 75% color bars.9
Levels
According to the TEA1002 datasheet,19 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.
| 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
| 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
See also
References
References
- TEA1002 PAL Colour Encoder and Video Summer. Mullard. 1982. p. 1. Archived from the original on 21 October 2022.
- "Machine: Mullard TEA1002 PAL colour encoder (tea1002)". Vas the Man’s Arcade.
- Graham, Adrian. "AlphaTantel Viewdata Terminal". Binary Dinosaurs. Retrieved 2023-05-02.
- Graham, Adrian. "AlphaTantel Viewdata Terminal Motherboard". Binary Dinosaurs.
- "Machine: AlphaTantel (alphatan)". Vas the Man’s Arcade.
- Microvector 256 Operating Manual (PDF). Climax Computers. 1983.
- Jenkins, Tony (June 1984). "TV Test Pattern Generator" (PDF). Television. p. 436.
- "TEA1002 PAL COLOUR ENCODER AND VIDEO SUMMER". Fabian Enterprises. 2013.
- TEA1002 PAL Colour Encoder and Video Summer. Mullard. 1982. p. 6. Archived from the original on 21 October 2022.