Do any existing or announced LCOS-based RPTVs have a 1:1 mode?

All of the Sony's are 1:1, although you lose some pixels around the edges because of overscan. I believe all of the JVC ones are too, but I'd have to look at the specs to confirm.

All of the Sony's are 1:1, although you lose some pixels around the edges because of overscan. I believe all of the JVC ones are too, but I'd have to look at the specs to confirm.

This seems strange-- you shouldn't have any overscan if you are feeding a digital signal over HDMI. I don't lose any pixels on my HP MD6580N when I put up test data. I thought you only have overscan with CRT-based products?

Almost all HDTVs overscan 5-7% when using HDMI/DVI or component since they are trying to emulate a standard CRT TV. Most of then do not overscan when using a VGA interface since they they are emulationg a PC monitor.
The way to check is to run a PC desktop appllication and if you can't see the task bar the TV is overscaning the input using its built in firmware.
Without firmware overscan you may still get up to 1% optical overscan which is done to insure that the edge of the video is under the Bezel and does not appear on the screen.
I have read that some of the Sonys have firmware overscan which cannot be disabled.
There is nothng wrong with overscan when watching TV since all the TV networks assume that overscan will occure so they place no meaningfull content near the edges which therfore makes the meaningfull content larger.
PC applications on the other hand do exactly the opposite since they assume they are being run on PC monitors which historicaly have always had a thin black border around the edges of the video.

All of the Sony's are 1:1, although you lose some pixels around the edges because of overscan.Unless I am mistaken on the meaning of "1:1", this would appear to be a contradictory statement. I thought that overscan and 1:1 are mutually exclusive. Overscan is in practice like a "zoom"; the 1920x1080 pixels of the display device are mapped to a slightly smaller area of the incoming picture in order to crop off the edges. To do this requires scaling of the picture (along with the inherent artifacts).

I'm looking for a TV that can be set to 1:1 pixel mapping, or zero overscan, over the HDMI connnection, so that a 1920x1080 signal can be fully displayed at the TV's native resolution with no scaling. I know some DLP and LCD TVs have a mode for this (in some cases accessible only through the service menu), and I'm wondering if any LCOS displays offer this. Mainly for HTPC and gaming console use (where every pixel counts and overscan is unwanted), but I understand 1:1 pixel mapping can also improve the quality of Blu-ray and HD-DVD.

I would like to know this as well

No, 1:1 means that for every pixel of data you have an active pixel being generated. So if you draw a 1 pixel line you will get exactly 1 pixel, 2 pixel line gets 2 pixels, etc...

For example, the chips in the Sony SXRDs are actually projecting every pixel in your image, it's just that some of that projected image is projecting outside the screen. If you physically adjusted the screen you could see the entire image. However, if you "unzoomed" the image electronically, you would see the entire picture on the viewable part of the screen, but it would no longer be 1:1 because you would be displaying the 1920x1080 image using a smaller number of pixels (those that actually show on the screen).

I have not seen any rear projection televisions that don't overscan on normal television signals. Some won't on a PC signal, but some even will on those. How much they overscan and how adjustable the overscan is varies from TV to TV.

One more thing, I have the Sony A2000 SXRD and it does incredibly well with the Playstation 3 on Blu-Ray and games. Using the standard settings I can get the overscan down to about 2.0 to 2.5%, so it isn't a problem. I would not, however, use it as a PC monitor since you do get some overscan on the HDMI input and the VGA input has limited resolution. The XBR2 does full resolution on the VGA port, so that's a better match to use if you want to use it as a PC monitor.

No, 1:1 means that for every pixel of data you have an active pixel being generated. So if you draw a 1 pixel line you will get exactly 1 pixel, 2 pixel line gets 2 pixels, etc... For example, the chips in the Sony SXRDs are actually projecting every pixel in your image, it's just that some of that projected image is projecting outside the screen.Yes, you are describing optical overscan (part of the projected image is obscured by the bezel) as opposed to digital overscan (the picture is electronically zoomed/scaled to crop the edges). Sounds like the Sony SXRDs have no digital overscan/processing on a 1080p signal, so 1:1 pixel mapping (Good!). But I agree the 2% optical overscan is more than I would want for PC use.

How about the JVC DILA sets - 1:1 pixel mapping? If so, how much optical overscan?

Yes, you are describing optical overscan (part of the projected image is obscured by the bezel) as opposed to digital overscan (the picture is electronically zoomed/scaled to crop the edges). Sounds like the Sony SXRDs have no digital overscan/processing on a 1080p signal, so 1:1 pixel mapping (Good!). But I agree the 2% optical overscan is more than I would want for PC use.

How about the JVC DILA sets - 1:1 pixel mapping? If so, how much optical overscan?

I tried 1080 resolution on my JVC (via DVI->HDMI conversion cable) and it has a ton of overscan. Bumping down the resolution from 1920x1080, even over HDMI (as opposed to VGA) resulted in minimal overscan. I think 1760x1000 (or something similar) made the picture on the screen almost completely visible. But at 1080, with the settings I had (out of the box, don't know if there's an overscan disabling feature), I couldn't even see the taskbar due to overscan. But I have no reason to believe it doesn't do a digital 1:1 mapping.

Yes, you are describing optical overscan (part of the projected image is obscured by the bezel) as opposed to digital overscan (the picture is electronically zoomed/scaled to crop the edges). Sounds like the Sony SXRDs have no digital overscan/processing on a 1080p signal, so 1:1 pixel mapping (Good!). But I agree the 2% optical overscan is more than I would want for PC use.

But on a PC it's easily taken care of with a custom resolution or resolution within a resolution. And I think a PC is the only source this would be a problem with, because nothing is even close to being cut off with console games or TV channels where they run tickers and have graphics up the side (like ESPN-HD).

I tried 1080 resolution on my JVC (via DVI->HDMI conversion cable) and it has a ton of overscan. Bumping down the resolution from 1920x1080, even over HDMI (as opposed to VGA) resulted in minimal overscan. I think 1760x1000 (or something similar) made the picture on the screen almost completely visible. But at 1080, with the settings I had (out of the box, don't know if there's an overscan disabling feature), I couldn't even see the taskbar due to overscan. But I have no reason to believe it doesn't do a digital 1:1 mapping.
If you had to lower the resolution of your output by underscanning it to 1760x1000 you were just getting the appearance of 1:1 pixel mapping since your TV was overscanning it back up to 1920x1080.

Since the TV requires 1920x1080, The drivers have to output that size but have the desktop work in a smaller area, so you will still maintain your 1:1. The only problem with this is that some software doesn't like some of the custom desktop sizes. I don't bother hooking a PC to mine so I can't give you any specifics. I'm sure that someone that has messed with it can give you all the details.