vesa mode 105h or 117h

[Lawrence]

I am trying to access the video memory in vesa modes 105h or 117h. These
modes are 1024x768. When I try to fill the screen, I only fill in the top
75%. My question is how do I access the complete video memory? It seems this
is an issue with the 65k block, how do I access the other blocks?

memset( (char *) 0xA0000, 0x0E, 0x10000);

Lawrence

 

[Joona I Palaste]

I am trying to access the video memory in vesa modes 105h or 117h. These
modes are 1024x768. When I try to fill the screen, I only fill in the top
75%. My question is how do I access the complete video memory? It seems this
is an issue with the 65k block, how do I access the other blocks?

memset( (char *) 0xA0000, 0x0E, 0x10000);

This is not a question about C, it's a question on how your computer's
video memory operates. Please ask in a newsgroup dedicated to your own
computer implementation.

--
/-- Joona Palaste ([email protected]) ------------- Finland --------\
\-------------------------------------------------------- rules! --------/
"A bee could, in effect, gather its junk. Llamas (no poor quadripeds) tune
and vow excitedly zooming."
- JIPsoft

 

[alex]

I am trying to access the video memory in vesa modes 105h or 117h. These
modes are 1024x768. When I try to fill the screen, I only fill in the top
75%. My question is how do I access the complete video memory? It seems
this is an issue with the 65k block, how do I access the other blocks?

Look up Bank switching. The 64k limit is not a VESA limitation,
but a limitation of real mode memory segmentation. Make a call
to VESA to switch to the next bank and you'll get access to the next
64k

if you're using protected mode, you OR the graphic mode
with 0x4000 and that enabled LFB (Linear Frame Buffer),
My using DPMI physical address mapping, you can access virtually ALL
of the display memory in 1 hit (none of this 64 nonsense)

Read up on

* DPMI Physical address mapping
* VESA LFB modes.

if you're in real mode, you're stuck with 64k segments and having to
use bank switching (a pain).

Alex

 

[alex]

I was assuming you're using DOS (before anyone flames me for
stating "DPMI")

 

[Joona I Palaste]

Look up Bank switching. The 64k limit is not a VESA limitation,
but a limitation of real mode memory segmentation. Make a call
to VESA to switch to the next bank and you'll get access to the next
64k

if you're using protected mode, you OR the graphic mode
with 0x4000 and that enabled LFB (Linear Frame Buffer),
My using DPMI physical address mapping, you can access virtually ALL
of the display memory in 1 hit (none of this 64 nonsense)

Read up on

* DPMI Physical address mapping
* VESA LFB modes.

if you're in real mode, you're stuck with 64k segments and having to
use bank switching (a pain).

And what do you think any of this has to do with C?

--
/-- Joona Palaste ([email protected]) ------------- Finland --------\
\-------------------------------------------------------- rules! --------/
"You have moved your mouse, for these changes to take effect you must shut down
and restart your computer. Do you want to restart your computer now?"
- Karri Kalpio

 

[alex]

And what do you think any of this has to do with C?

--

He is writing his application in C, I know its off topic.
Instead of being nasty (like you), I helped, because I knew
the answer to his question.

Just relax ok? It hasnt hurt anyone/anything.

Alex.

 

[alex]

And what do you think any of this has to do with C?

Actually, if you want to make that big a deal with his question being off
topic,
please show me a newsgroup dedicated to hardware programming. I'd be
interested in this myself. Perhaps he couldnt find one? Theres plenty of
groups
that discuss PC hardware, but programming of PC hardware?

 

[Mike Wahler]

He is writing his application in C,

That does not automatically make this issue topical.
It's the *language* itself which is the topic, not
any possible application of it.

Also, note that in comp.lang.c the term "C language" means
ISO standard C. Any included code falling outside that domain
causes the program to cease being a C program. This issue is
outside that domain.

I know its off topic.

You knew it was not topical, but you:
1) Did not indicate this to the OP.
2) Posted an equally off-topic message.

Instead of being nasty (like you),

As I'm pointing out in this message, it was *your* behavior
that was 'nasty' (perhaps 'disrespectful' would describe it
better), not Joona's. Joona has been a very helpful,
polite poster here for a very long time. He has already
proven his expertise to us. Regardless of who might have
written it, I cannot see how the question: "And what do you
think any of this has to do with C?" could be considered 'nasty'.
"Terse", perhaps, but imo emotionally neutral.

I helped,

Actually your reply was potentially far more harmful than
helpful.

because I knew
the answer to his question.

I know the answers to many questions which are not topical
(but many of which are asked) here. But they're not topical,
so I don't answer them here (if I answer at all, it would be
with a notification about topicality, and possibly a redirection
to a more appropriate group.

Just relax ok? It hasnt hurt anyone/anything.

You have potentially harmed a large number of individuals,
because your off-topic answer could lead them to believe
that this is indeed a C issue when it's really not. This
misinformation can and does harm them and others; in
both learning and commercial enviroments, in many ways.
These are issues which cause the 'regulars' to point out
off-topic material. I certainly don't want to end up
working with someone who does not really know C but
believes he does.

Finally, please see the "welcome message" to which I posted
a link elsewhere in this thread. Thank you.



-Mike

 

[Mike Wahler]

Actually, if you want to make that big a deal with his question being off
topic,
please show me a newsgroup dedicated to hardware programming.

Often an off-topic notice will include suggestions of
other places to look for information. But imo it's not
reasonable to expect this to always be the case. The
primary thing folks do here is discuss C, not how to
find information on the internet.

I'd be
interested in this myself. Perhaps he couldnt find one? Theres plenty of
groups
that discuss PC hardware, but programming of PC hardware?

www.google.com
www.groups.google.com

Also, many PC manufacturers provide extensive hardware documentation.
Try one or more of their web sites.

-Mike

 

[Mike Wahler]

I was assuming you're using DOS (before anyone flames me for
stating "DPMI")

I hereby flame you (as well as the OP) for posting an off-topic message.

Both of you, before posting here again, please read (and observe):
http://www.angelfire.com/ms3/bchambless0/welcome_to_clc.html
Thank you.

-Mike

 

[Keith Thompson]

He is writing his application in C, I know its off topic.
Instead of being nasty (like you), I helped, because I knew
the answer to his question.

Just relax ok? It hasnt hurt anyone/anything.

The point of not giving off-topic answers here is that the rest of us
don't have the knowledge to check whether they're correct.
Personally, I feel much more comfortable posting information about C
in comp.lang.c because I know that there are plenty of experts who
will jump in and correct any errors I might make, and because the
discussion can benefit all the readers of the newsgroup, not just the
one person who asked the question.

We try to be as helpful as we can. In the case of a question about,
for example, MS-DOS, the best help we can give is to advise the
questioner to ask in a more appropriate newsgroup.

Yes, we're pickier than most newsgroups are about topicality. Because
of the volume we deal with, and for other reasons, we have to be.

 

[alex]

Actually your reply was potentially far more harmful than
helpful.

yes, we better call in the HAZMAT team. Global catastrophy
is imminent.

You have potentially harmed a large number of individuals,
because your off-topic answer could lead them to believe
that this is indeed a C issue when it's really not.

That would contradict everything you just said. I see a larger amount
of individuals acknowledging this has nothing to do with the "C" language
itself, so, if you start to talk about carrots, its unlikely someone will
get confused
and think you're talking about tomatoes.

This
misinformation can and does harm them and others; in
both learning and commercial enviroments, in many ways.

Rubbish. nobody is "forcing" them to read and absorb it in.
most will simply ignore what is not relevant or interesting to them.

These are issues which cause the 'regulars' to point out
off-topic material.

Assumption is the mother of all fuckups.

I certainly don't want to end up
working with someone who does not really know C but
believes he does.

Finally, please see the "welcome message" to which I posted
a link elsewhere in this thread. Thank you.

nah.. this isnt a moderated group, so I dont care to do so.

 

[alex]

Often an off-topic notice will include suggestions of
other places to look for information. But imo it's not
reasonable to expect this to always be the case. The
primary thing folks do here is discuss C, not how to
find information on the internet.


www.google.com
www.groups.google.com

Do i connect to those on port 119? ok when i said groups, perhaps I should
have prefixed it with "news"

Also, many PC manufacturers provide extensive hardware documentation.
Try one or more of their web sites.

Rubbish. Most manufacturers keep it a secret (besides intel and amd).
Approach
nVidia for a copy of an architecture manual on one of their video cards and
see what
they tell you. But in this case the VESA spec is widely available on the
net. I _did_
hint to the guy he whould read it as it would answer a lot of his questions.

 

[Keith Thompson]

Actually, if you want to make that big a deal with his question
being off topic, please show me a newsgroup dedicated to hardware
programming. I'd be interested in this myself. Perhaps he couldnt
find one? Theres plenty of groups that discuss PC hardware, but
programming of PC hardware?

comp.arch.embedded, perhaps?

In any case, the lack of an appropriate newsgroup (assuming there is
such a lack) doesn't make the question topical here. If nothing else,
there's always comp.misc.

 

[Mike Wahler]

nah.. this isnt a moderated group, so I dont care to do so.

*PLONK*

-Mike

 

[jacob navia]

He is writing his application in C, I know its off topic.
Instead of being nasty (like you), I helped, because I knew
the answer to his question.

Just relax ok? It hasnt hurt anyone/anything.

I agree with you.

Your answer was informative and to the point.

I think your answer raised the discussion level.

jacob

 

[Alex]

ROFLMAO!

Gotta love these uptight newsgroup nazi gestapo guys.
If it doesnt conform to paragraph 3.12a of the newsgroup usage
laws its a "Plonk".

Plonk all you want. I wont lose any sleep over it

Actually, "Plonk" to you too. You n00b.
baha! "capped"

 

[Mike Wahler]

I agree with you.

Your answer was informative and to the point.

I think your answer raised the discussion level.

Both the question and the answer *lowered* the discussion
level to being outside the scope of comp.lang.c

-Mike

 

[Lawrence]

Alex,

The Bank Switching hint was exactly what I needed. Thanks for the help.

Lawrence

 

[Alex]

No problem

Alex

Alex,

The Bank Switching hint was exactly what I needed. Thanks for the help.

Lawrence