[ltp] Vote on the design of future ThinkPad

[Richard Neill]

Eric Jorgensen wrote:
> On Thu, 21 Dec 2006 23:57:26 +0000
> Richard Neill <rn214@hermes.cam.ac.uk> wrote:
> 
> 
>> Yes...but a DVI socket can easily be converted to VGA with a simple 
>> adapter, costing about $2. Not so easy to go the other way. Besides 
>> which, VGA really doesn't work if the cable is longer than 2m - the 
>> projector in our lab is on the end of a 20m cable, with 3 joins in it,
>> and the ghosting is horrid!
> 
> 
>    That depends on the quality of the cable. 
> 
>    Not to say you can easily do 20 meters, but if you have one (1) cable
> with no joins, and that cable contains 3 75-ohm coaxial cables for red,
> green, and blue, you should be able to get at least half a dozen meters
> without ghosting. 

Depending, of course, on whether the impedances of the Laptop, Cable, 
and Projector all match exactly. [Murphy virtually demands that they 
don't, of course!] The problem with long cables isn't that the impedance 
mismatch is worse, it's that the time-delay is longer, hence ghosting 
occurs over a greater number of pixels.

Richard