How do I write to VGA registers? 
Author Message
 How do I write to VGA registers?

Hi,

I need to know how to write a value to a specific VGA register and
index.  Code is not necessary, just a good simple explination.  I want
to be able to import the files generated by the program tweak and
initilize the unchained mode that it defines.

Thanks,

Greg



Wed, 18 Jun 1902 08:00:00 GMT  
 How do I write to VGA registers?

Quote:

> Hi,

> I need to know how to write a value to a specific VGA register and
> index.  Code is not necessary, just a good simple explination.

There isn't exactly a way to summarize this globally for all VGA
registers, since the VGA has several components which use different
register sets.  The VGA registers are broken down into 5 groups -- the
general registers, which have unique port addresses; the sequencer
registers, 5 of them multiplexed to 03c4h/03c5h; the CRT controller
registers, 25 of them multiplexed to 03d4h/03d5h for color video modes,
or 03b4h/03b5h for monochrome modes; the graphics controller registers,
9 of them multiplexed to 03ceh/03cfh; and the attribute controller
registers, 21 of them multiplexed to 03c0/3c1h.

The attribute controller registers are different from the others,
because one port is used for both the index and data, and is controlled
by a flip-flop tied to one of the general registers.

In short, there's *is* no simple, concise way to answer this, and
several books have entire chapters dedicated to this topic.

Quote:
> I want
> to be able to import the files generated by the program tweak and
> initilize the unchained mode that it defines.

I have TWEAK floating around on my hard drive.  Runs in my mind that
source is included, so maybe the best thing to do is just translate its
loader source from C to TP (best done by hand).  If you're not sure you
can do this, I can probably take a look and see if I can accomplish
something.  :-)

Quote:
> Thanks,

> Greg

--
Scott Earnest        | We now return you to our regularly |



Wed, 18 Jun 1902 08:00:00 GMT  
 
 [ 2 post ] 

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