[nvda] Re: video system hooks

Yeah, those were fun times heh.
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan
----- Original Message ----- From: "Chris & Doris" <chipmunks@xxxxxxx> 
To: <nvda@xxxxxxxxxxxxx>
Sent: Thursday, May 28, 2009 2:33 PM
Subject: [nvda] Re: video system hooks
and actually jaws used to be portable with using just display hooks back in the day of win 9x. back then, you could copy an installed version of jaws onto a portable drive or cd and run it from there on any win 9x computer without having to install a video intercept driver. the need for video intercept drivers only came with screenreaders giving access to windows 2000, xp and so on. jaws already worked with windows NT 4.0 and I assume needed a video intercept for that but on this I am not sure. 

hth

Doris

At 12:18 PM 5/28/2009 -0500, you wrote:
This is because jaws uses what is called video intercept, or display chaining. it is not portable because in order for it to run the display chaining manager, or dcm has to be installed on the computer it is running on. If nvda gets display hooks it will not affect it's portability. display hooks are quite different from display chaining. instead of capturing video information before it reaches the video card itself, display hooks capture the information the application is sending to the video card and then passes it on to the video card. it does not rely on any special software to be installed. it doesn't need any. Nvda will use this method, rather than display chaining for this reason. 
Thanks
Kendell clark
On 5/28/2009 12:11 PM, developer wrote:

do you know example of jaws.
jaw is not portable with system hooks
so system hooks
bye bye
----- Original Message -----
From: <mailto:jkenn337@xxxxxxxxx>Josh
To: <mailto:nvda@xxxxxxxxxxxxx>nvda email list
Sent: Thursday, May 28, 2009 4:02 PM
Subject: [nvda] video system hooks

Hi,
video system hooks will not decrease portability. System access is a good example of a portable screen readerwith video system hookss. 

Josh

Josh email is    <mailto:jkenn337@xxxxxxxxx>jkenn337@xxxxxxxxx
msn: <mailto:kenn6498ku@xxxxxxxxxxx>kenn6498ku@xxxxxxxxxxx
skype: jkenn337




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