Almost all computer monitors and TVs use the same technology that first appeared in the 1940s: the CRT. How both consumers and manufacturers would love a viable flat panel display. LCDs dont make the grade: its too hard - and expensive - to produce LCDs larger than 20 inches diagonal.

One technology available off the shelf right now is the gas plasma display. This uses tiny gas-filled cells which, when excited by an electric current, produce a discharge which in turn causes the phosphor coating on the surface of the cell to glow. Each pixel is formed by three of these cells.

Until recently, plasma displays have been marked by three characteristics: they have been large, they have been expensive and they have been limited in resolution. Sonys PFM-42B1 breaks away from this last limitation.
Its still expensive, but at under $14,000 we are talking about a price fall of over 30 per cent over a couple of years. And it is large, which is a virtue of course. The diagonal of the visible part of this display is no less than 1,058mm, or 42 inches. And the physical resolution has been bumped up to 1,024 x 1,024 pixels. All this comes in a package only a little larger than the screens viewing area, and a depth of just 83mm.

The PFM-42B1 falls between Sonys professional and consumer equipment divisions, so it endeavours to provide everything to everyone. Take inputs, for example. It comes with two standard 15 pin monitor sockets. But these can be reconfigured with the press of a button on the remote and the use of an adaptor cable to accept component video (that is, three separate signals for luminance and the two colour difference signals provided by most quality DVD players). It is also fitted with S-Video and composite video inputs.

On the home entertainment front, the displays electronics are capable of accepting standard NTSC and PAL broadcast quality signals, as well as the various likely manifestations of HDTV signals up to 1,080 lines. No TV tuner or speakers are built in, so you will have to provide the signal source from a VCR, DVD player or a digital TV decoder.

On the computer side, the display supports input signals in resolutions from 640 x 350 up to 1,600 x 1,200 (it tops out at 60 Hertz refresh on this one).
The display is in widescreen format, which means the aspect ratio is 16:9 rather than the usual monitors 4:3. This leads to a problem well get to in a moment. But first, a word about its home entertainment performance. That word is superlative. Being bit-mapped, the display suffers none of the geometry problems that afflict almost all CRT TVs. Nor does it suffer from the restricted viewing angles and visible scan lines that generally accompany rear projection TVs that youll see in the pub. Youll need a top quality LCD projector to go close in picture quality, but this will cost you the plasma displays rich colours and deep blacks.

In a computer context, things arent quite as good. And it all has to do with resolution. Virtually all computer display adaptors these days expect to be producing square pixels, with more pixels on the horizontal than there are on the vertical. The PFM-42B1 uses pixels that are markedly wider than they are tall (the three coloured cells constituting each pixel are in a horizontal row). If you set the screen to display in 4:3 aspect ratio (which of course leaves black bars down either side of the screen) you get 1,024 pixels of height, but only 768 across. So to get 1:1 or better mapping of the input signal to the display in both dimensions, you cannot even achieve SVGA resolution. Unless, that is, you place the display on its side, which is perfectly permissible.

The downsampling that allows the display of higher resolution images than
the display is physically capable of is exceptionally good, producing fairly readable standard text at 1,280 by 1,024 pixels. But the purpose of this display isnt for everyday use with your computer, but for presentations to moderate crowds of people. A carefully designed PowerPoint presentation, shown using the widescreen aspect ratio for full impact, uses the PFM-42B1 to best advantage. Or for pure indulgence, pull up a chair, microwave the popcorn and set yourself down to watch a feature length DVD movie.