TEA1002
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.
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,[1] colors are formed by the combination of three signals, roughly equivalent to the HSL colorspace:
- Luminance
- Chroma angle (º)
- Chroma percentage (%, 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 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.
| 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
References
- TEA1002 PAL Colour Encoder and Video Summer. Mullard. 1982.
- "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.
- Jenkins, Tony (June 1984). "TV Test Pattern Generator" (PDF). Television. p. 436.
- "TEA1002 PAL COLOUR ENCODER AND VIDEO SUMMER". Fabian Enterprises. 2013.
