Access VGA ports through S/W??????

(Sonu) wrote in message . com...
Hi all,

I asm trying to access the video port (i.e conventional VGA port)
which is connected to the monitor via a DSUB line.

Okay there are various issues here that you haven't considered (or at
least you haven't mentioned). (1) Is this running under Windows or
DOS? (2) video cards are considerably more complicated than simply
accessing their I/O ports. There are also memory-mapped I/O ranges
too.

The resource tab of my graphics driver shows me the addresses for the
ports as below:

I/O Range : 0x3b0-0x3bb
I/O Range : 0x3c0-0x3DF

Can I acccess the port addresses as it is in my Driver for porting the
data out or I have to map it into logical address as in the case if my
Port is mapped in Memory Space of the OS.

Okay first of all, the i/o ports are only really used for controlling
the modes and other status info of the video card, such as its
resolution, color depth, blanking intervals, etc. The actual pictures
are drawn by writing to either of a couple of memory-mapped video
ranges, known as the video buffer. The traditional video buffer
address is between memory addresses 0x000A0000 to 0x000BFFFF, which
happens to be the address 640K to 768K. And now more modern AGP video
cards have an alternative video buffer range that you'll notice
FA000000 to FBFFFFFF (corresponding to 4000MB to 4032MB).

I tried porting the data out directly but had no effect on my VGA
port.

The other thing you haven't considered is that you're running under
Windows. Windows or any other Protected mode operating system, such as
Linux, will automatically prevent you from accessing these ports and
memory locations directly. The OS will manage these access itself, and
it will prevent user-level programs from gaining access to these
things and screwing up the display.

Yousuf Khan

Greets all,

Thanks ffer the ideas which you had dropped to me in the box.
Well, I need to tell you all that I wish to access the port from my
User Aplllication but through a proper port driver which I already had
made.

Actually I have tested my port driver on parallel port,where it is
giving out data properly.In my port driver I have used HAL(Hardware
Abstraction layer) supplied function
"WRITE_PORT_UCHAR/ULONG(PUCHAR Port,Int Byte)"
And from my user application I pass on the port address and the data
to the driver through IOCTL Codes.

But when I issue the I/O mapped range for VGA port (I/o :::::
0x3c0---0x3da)
it shows me no activity on the lines.

I need to know how can I pass Data through the DSUB channel along the
SDA pin of the VGA cabvle which plugs into the monitor.Please find me
some way of doing this.

Any Idea are welcome.

-with thanks and regards,
sonu




(Yousuf Khan) wrote in message . com...
(Sonu) wrote in message . com...
Hi all,

I asm trying to access the video port (i.e conventional VGA port)
which is connected to the monitor via a DSUB line.

Okay there are various issues here that you haven't considered (or at
least you haven't mentioned). (1) Is this running under Windows or
DOS? (2) video cards are considerably more complicated than simply
accessing their I/O ports. There are also memory-mapped I/O ranges
too.

The resource tab of my graphics driver shows me the addresses for the
ports as below:

I/O Range : 0x3b0-0x3bb
I/O Range : 0x3c0-0x3DF

Can I acccess the port addresses as it is in my Driver for porting the
data out or I have to map it into logical address as in the case if my
Port is mapped in Memory Space of the OS.

Okay first of all, the i/o ports are only really used for controlling
the modes and other status info of the video card, such as its
resolution, color depth, blanking intervals, etc. The actual pictures
are drawn by writing to either of a couple of memory-mapped video
ranges, known as the video buffer. The traditional video buffer
address is between memory addresses 0x000A0000 to 0x000BFFFF, which
happens to be the address 640K to 768K. And now more modern AGP video
cards have an alternative video buffer range that you'll notice
FA000000 to FBFFFFFF (corresponding to 4000MB to 4032MB).

I tried porting the data out directly but had no effect on my VGA
port.

The other thing you haven't considered is that you're running under
Windows. Windows or any other Protected mode operating system, such as
Linux, will automatically prevent you from accessing these ports and
memory locations directly. The OS will manage these access itself, and
it will prevent user-level programs from gaining access to these
things and screwing up the display.

Yousuf Khan

Sonu wrote:
Greets all,

Thanks ffer the ideas which you had dropped to me in the box.
Well, I need to tell you all that I wish to access the port from my
User Aplllication but through a proper port driver which I already had
made.
snip
I need to know how can I pass Data through the DSUB channel along the
SDA pin of the VGA cabvle which plugs into the monitor.Please find me
some way of doing this.

Any Idea are welcome.

IIRC, you need to go through the VESA bios, there is no standard way of
accessing the DDC info through registers.

You are probably going about this the wrong way.
Do some googling for
DDC VESA
and your language/OS of choice.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
Lord, grant me the serenity to accept that I cannot change, the
courage to change what I can, and the wisdom to hide the bodies
of those I had to kill because they ****ed me off. - Random