Windows 2000 Re: "full-screen" DOS window doesn't fill screen

  • Thread starter Thread starter Ted Davis
  • Start date Start date
T

Ted Davis

On Sat, 07 Jun 2008 14:25:37 -0700, ynotssor wrote:

> I have an old DOS program that runs in a cmd.exe window which can be made
> to use the full screen with Alt-Enter. This works properly on another
> win200 machine, but on a Toshiba laptop the full screen mode fills the
> width but NOT the height of the screen.
>
> I've made sure that the Properties and the Console Windows Properties of
> the C:\winnt\system32\cmd.exe window are the same on both machines, using
> Raster Fonts 8x12 and the same Layout, Screen Buffer 80x420 and Window
> Size 80x25.
>
> Still, the fullscreen mode on the laptop doesn't fill the vertical of the
> screen for any cmd.exe application, even just a command prompt.
>
> What am I mssing here, please?

Most likely, you are missing the fact that the digital display has fixed
numbers of pixels vertical and horizontal (and therefore a fixed aspect
ratio), and that only video modes that evenly divide those numbers and
have the same aspect mode can be displayed properly - anything else will
have to be underscanned in one direction or another, and many modes have
to be dithered as well to get them to display at all. Sometimes the
mismatch is so severe that the display can't show a stable picture at all.

The only solutions are to accept that digital reality is quantitised or
to use an analog monitor.

--

T.E.D. (tdavis@mst.edu) MST (Missouri University of Science and Technology)
used to be UMR (University of Missouri - Rolla).
 
In news:pan.2008.06.07.23.56.12.328000@umr.edu,
Ted Davis typed:

>> Still, the fullscreen mode on the laptop doesn't fill the vertical
>> of the screen for any cmd.exe application, even just a command
>> prompt.
>>
>> What am I mssing here, please?
>
> Most likely, you are missing the fact that the digital display has
> fixed numbers of pixels vertical and horizontal (and therefore a
> fixed aspect ratio), and that only video modes that evenly divide
> those numbers and have the same aspect mode can be displayed
> properly ...

No, I'm not missing that fact. The aspect ratio on the working display is
1152/864 = 4/3 = 1.3333..., the same as on the 800/600 laptop display.
 
Last edited by a moderator:
On Sat, 07 Jun 2008 22:30:02 -0700, ynotssor wrote:

> In news:pan.2008.06.07.23.56.12.328000@umr.edu, Ted Davis
> typed:
>
>>> Still, the fullscreen mode on the laptop doesn't fill the vertical of
>>> the screen for any cmd.exe application, even just a command prompt.
>>>
>>> What am I mssing here, please?
>>
>> Most likely, you are missing the fact that the digital display has fixed
>> numbers of pixels vertical and horizontal (and therefore a fixed aspect
>> ratio), and that only video modes that evenly divide those numbers and
>> have the same aspect mode can be displayed properly ...
>
> No, I'm not missing that fact. The aspect ratio on the working display is
> 1152/864 = 4/3 = 1.3333..., the same as on the 800/600 laptop display.

The working DOS full screen is 640 x 480. 640 does not evenly divide 1152,
nor does 480 evenly divide 864 - the attempt to display 640 x 480 on 1152
x 864 necessarily results in siginificant compromises and approximations.

--

T.E.D. (tdavis@mst.edu) MST (Missouri University of Science and Technology)
used to be UMR (University of Missouri - Rolla).
 
Last edited by a moderator:
In news:pan.2008.06.08.16.04.59.844000@umr.edu,
Ted Davis typed:

>>>> Still, the fullscreen mode on the laptop doesn't fill the vertical
>>>> of the screen for any cmd.exe application, even just a command
>>>> prompt.
>>>>
>>>> What am I mssing here, please?
>>>
>>> Most likely, you are missing the fact that the digital display has
>>> fixed numbers of pixels vertical and horizontal (and therefore a
>>> fixed aspect ratio), and that only video modes that evenly divide
>>> those numbers and have the same aspect mode can be displayed
>>> properly ...
>>
>> No, I'm not missing that fact. The aspect ratio on the working
>> display is 1152/864 = 4/3 = 1.3333..., the same as on the 800/600
>> laptop display.
>
> The working DOS full screen is 640 x 480. 640 does not evenly divide
> 1152, nor does 480 evenly divide 864 - the attempt to display 640 x
> 480 on 1152 x 864 necessarily results in siginificant compromises and
> approximations.

640/480 = 4/3 = 1.3333..., the same aspect ratio. The DOS program displays
properly full-screen on the 1152x864 screen, contrary to your assertion.
 
Last edited by a moderator:
On Sun, 08 Jun 2008 11:05:07 -0500, Ted Davis put
finger to keyboard and composed:

>On Sat, 07 Jun 2008 22:30:02 -0700, ynotssor wrote:
>
>> In news:pan.2008.06.07.23.56.12.328000@umr.edu, Ted Davis
>> typed:
>>
>>>> Still, the fullscreen mode on the laptop doesn't fill the vertical of
>>>> the screen for any cmd.exe application, even just a command prompt.
>>>>
>>>> What am I mssing here, please?
>>>
>>> Most likely, you are missing the fact that the digital display has fixed
>>> numbers of pixels vertical and horizontal (and therefore a fixed aspect
>>> ratio), and that only video modes that evenly divide those numbers and
>>> have the same aspect mode can be displayed properly ...
>>
>> No, I'm not missing that fact. The aspect ratio on the working display is
>> 1152/864 = 4/3 = 1.3333..., the same as on the 800/600 laptop display.
>
>The working DOS full screen is 640 x 480. 640 does not evenly divide 1152,
>nor does 480 evenly divide 864 - the attempt to display 640 x 480 on 1152
>x 864 necessarily results in siginificant compromises and approximations.

I just tried full screen DOS mode on a Win98 socket 7 desktop PC with
a 15" 1024x768 LCD monitor (with an analogue interface).

For 80 cols x 25 rows, my LCD reports that my graphics card resolution
is 720x400. This would equate to a cell size of 9Hx16V. Allowing for a
single pixel between characters (have I got this right?), that would
mean a font size of 8Hx15V.

Doing the same for 80Cx50R, we get 720x400 resolution, a cell size of
9Hx8V, and a font size of 8Hx7V.

Again for 80Cx43R (mode co80,43), we get 640x350 resolution, 8x8 cell
size (with 6 pixels left over in the vertical direction), and a font
size of 7x7.

I obtained identical results on a 486 Win95 box when booted in real
DOS mode (different graphics chipset). I presume the fonts (and font
sizes) are hard coded into the video ROM BIOS of the graphics card.

Would it be possible to experiment with an external monitor that could
detect the resolution being output by the laptop's graphic subsystem?
Would that reflect the resolution being used by the internal display?

BTW, in Win98SE, the font size selected in a windowed DOS box (eg the
OP's 8x14) is ignored when switching to full screen mode. I have no
idea whether Win2K behaves the same way.

I suggest that the OP takes accurate measurements of the width and
height of a DOS text screen in full screen mode. Maybe the measured
aspect ratio will give a clue as to what is going on.

Could the OP's issue be addressed by means of a .cpi file?
http://www.procon.com.au/HVCPIFnt.htm

Would command.com and cmd.exe produce different results?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
Last edited by a moderator:
On Fri, 13 Jun 2008 16:08:50 +1000, Franc Zabkar
<fzabkar@iinternode.on.net> put finger to keyboard and composed:

>For 80 cols x 25 rows, my LCD reports that my graphics card resolution
>is 720x400. This would equate to a cell size of 9Hx16V. Allowing for a
>single pixel between characters (have I got this right?), that would
>mean a font size of 8Hx15V.

Sorry, I got it wrong. It seems that any single-pixel character
separation is accounted for in the font. So font size = cell size.

Furthermore, after switching between 25/43/50 row screen modes (in
real DOS mode), I eventually achieved a font/cell size of 8x14 at a
resolution of 640x350 for "mode c080,25". At other times the same mode
setting resulted in a 720x400 resolution and a 9x16 font.

The following sequence illustrates what happens:

mode co80,50 -> 720x400, 9x8 font
mode co80,25 -> 720x400, 9x16 font
mode co80,43 -> 640x350, 8x8 font
mode co80,25 -> 640x350, 8x14 font

For my testing I found that filling two consecutive lines with ASCII
character 177 best illustrated the above.

Maybe the OP could try a "mode co80,43" command followed immediately
by "mode co80,25" ???

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
"Franc Zabkar" <fzabkar@iinternode.on.net> wrote in message
news:m63654tq7fvmq81e3803ri9jo07q4hg2pq@4ax.com...
> On Fri, 13 Jun 2008 16:08:50 +1000, Franc Zabkar
> <fzabkar@iinternode.on.net> put finger to keyboard and composed:
>
> >For 80 cols x 25 rows, my LCD reports that my graphics card resolution
> >is 720x400. This would equate to a cell size of 9Hx16V. Allowing for a
> >single pixel between characters (have I got this right?), that would
> >mean a font size of 8Hx15V.
>
> Sorry, I got it wrong. It seems that any single-pixel character
> separation is accounted for in the font. So font size = cell size.
>
> Furthermore, after switching between 25/43/50 row screen modes (in
> real DOS mode), I eventually achieved a font/cell size of 8x14 at a
> resolution of 640x350 for "mode c080,25". At other times the same mode
> setting resulted in a 720x400 resolution and a 9x16 font.
>
> The following sequence illustrates what happens:
>
> mode co80,50 -> 720x400, 9x8 font
> mode co80,25 -> 720x400, 9x16 font
> mode co80,43 -> 640x350, 8x8 font
> mode co80,25 -> 640x350, 8x14 font
>
> For my testing I found that filling two consecutive lines with ASCII
> character 177 best illustrated the above.
>
> Maybe the OP could try a "mode co80,43" command followed immediately
> by "mode co80,25" ???
>
> - Franc Zabkar

Franc:

Did you read the entire thread?

His problem was already fixed by a "stretch" setting in the BIOS,
a common thing on laptops. It's a hardware thing that can't be fixed
by tinkering with MODE commands, et. al.


> --
> Please remove one 'i' from my address when replying by email.
 
Back
Top