There are several ways of supporting the virtual terminals.
One way is to keep complete screen buffers in the console card by whatever means.
Another is to query the screen for its contents when switching it out so the host can save it until
it is switched back in, at which time it can be refreshed. That would require some tricky stuff
on the host side, but it is not impossible. If you assume the host is not in an application but rather
at the command line, the program that causes the switch can query the screen contents and save
it in a file. Then when the host is re-activated, it can refresh the screen if the buffer file is present.
There would have to be specific code for each operating system, and the console card would have to
support a sequence that would allow the host to query the screen's state.
This is very doable.
On 1/5/2013 6:54 PM, John Monahan wrote: