- Source: TEA1002
The TEA1002 is a PAL video encoder chip produced by Mullard in 1982 and used on the Mattel Aquarius computer and AlphaTantel Prestel adapter.
It was also used on teletext decoders and color bar generators associated with video test equipment.
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
According to the TEA1002 datasheet, 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.
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.
See also
Thomson EF9345
Motorola 6845
TMS9918
MOS Technology VIC-II
List of home computers by video hardware
References
Kata Kunci Pencarian:
- TEA1002
- List of monochrome and RGB color formats
- Mattel Aquarius
- List of 8-bit computer hardware graphics
- Pro Electron
- List of home computers by video hardware
