Review: Matrox Millennium G450 DualHead (Page 4/9)

Posted: December 8, 2000
Written by: Tuan "Solace" Nguyen

DualHead Technology

DualHead is Matrox's multi-monitor support built into a single card solution. DualHead technology is set apart from traditional multi-monitor support because the second output device can be anything from an additional monitor, a TV, to a flat panel display. Additionally, the second display output can function at a different refresh rate and resolution than the primary display device. That way, you can lose a lot of the flicker that usually results from using a TV as a display device. And the displays are independent of each other.

On the G400 Matrox pulled this feat off by including dual CRT controllers and RAMDACs onto one board. With the G450, Matrox has integrated everything into the chip. This gives Matrox total control over visual quality and speed and they don’t have to rely on a third party to supply modules and filters.

The Hardware Behind DualHead

The Matrox G400 chip leveraged the MAG-TVO (Matrox’s proprietary TV encoder chip with an integrated RAMDAC which couldn’t support as resolutions as high as the main output) to output to a secondary display -- TV, VGA monitor or analog flat panel. Without this chip, Matrox would have needed multiple chips like TV output encoders and RAMDACs to support all the possible display configurations; a problem NVIDIA is facing due to the lack of commercially available TV-encoders with integrated RAMDACs. RAMDAC stands for Random Access Memory Digital to Analog Converter and is a chip that takes data from RAM and converts it into a signal your display device can understand.

With the G450, Matrox used the space saved from the die shrink to integrate the MGA-TVO core and TMDS transmitters on a single chip. TMDS or Transmission-Minimized Differential Signaling is used to output to digital flat panels. Using digital displays greatly enhance sharpness and color saturation. You’ll have to purchase the G450 DVI for this option though.

Currently, there are no commercially available third-party chips on the market that integrate a TV output encoder and a RAMDAC on a single chip. This is why people are finding it difficult to obtain GeForce2 MX based cards with TwinView technology. Board manufacturers and OEMs using the GeForce2 MX chip will have to source separate RAMDACs and TV encoders and populate them on the PCB to support all available display configurations. This adds to cost, design resources, and logistical issues incurred when dealing with multiple suppliers. What does this mean to you? Higher costs. Something you want to generally avoid when you’re looking to maximize and productivity and minimize spending.

There are many modes to choose from. Next page contains a list of what’s available and how they function.

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