Am Sonntag, den 01.05.2005, 13:06 -0400 schrieb Timothy Miller:

> Interesting approach #1:  Periodically, scan the VGA data and
> translate/scale it to another buffer that is read by the video
> contoller.
> 
> Interesting approach #2:  Catch writes to VGA memory and convert them
> immediately.

#1 won't work because each write to memory of a real VGA chip goes
through a 5-stage pipeline, with various logical operations performed at
each stage. One of the operations involves the value latched during the
last read, which means reading is not trivial either.
We absolutely need #2. We can add a second (even smaller) nanocontroller
to do #1 if it turns out that drawing a character on every write and/or
refreshing the whole screen after mode changes takes too long. How long
is a memory access and an I/O access allowed to take?


- Viktor Pracht

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