[Ham-Computers] RE: Windows 98 SE, Running DOS Applicaitons in Window?

Thu Oct 9 21:13:49 EDT 2008

>>> KD7JYK wrote:
I have a new monitor that is wrapping the full screen DOS applications from top to bottom, that is, the top 1" or so is on the bottom and everything is shifted up. 

>>> My reply:
OK, if I am reading this correctly, it sounds like a video sync issue.  Based on this, I believe your new monitor is connected via a standard 15-pin *analog* VGA cable, correct?

Most all monitors with an analogue input manufactured in the past 15 years or so have an auto-syncing feature that sets the monitor's horizontal and vertical sync rates to match what's comming out of the PC's video card.

The "standard" DOS text mode is 720x400 @ 70 Hz - this is what your PC boots up at and what is used if you boot directly into a DOS prompt.  When you open a Command Prompt from within Windows, it usually opens in a window - the size of which is determined by the font size and the window layout size in the Command Prompt properties.  The default "windowed" font size is 8x12 and the layout size is 80 columns by 25 rows.  If you change the number of columns or rows, the font size remains the same, but the window size will change accordingly.  Similiarly, if you change the font size, the window will change size to match the font, but it will still show the same number of rows/columns.

If you're running the Command Prompt "full screen", then the video mode changes to 80x25 "text" mode - just as if you're running in DOS.  The font used is the font that's burned into the video card's BIOS for 80x25 text mode - in the old IBM PC DOS days, using BASIC, this was known as screen mode 0 (zero).  This mode is still found on all PC based video cards today as the default video mode when the system boots up - IIRC, it's VGA mode 02h.  The pixel resolution for this mode is 720x400 @ 70Hz, but it's running fully in text mode (no bit-mode graphics).

Anyways, as mentioned earlier, the problem Kurt is seeing is probably due to a vertical sync mis-match.  In full-screen Command Prompt mode, the video card is using a different video mode (and sync rate) than when running in Windows GUI (graphics) mode.  If using an analogue VGA cable, the sync rate used by the video card may not match exactly what the monitor is expecting for that particular mode - the resulting image is often "shifted", "expanded", or "compressed".  This is what all the "screen geometry" controls are for on monitors and TV sets.  On a LCD monitor, these controls will typically be buried in a menu.  Better LCD monitors also have an "auto-sync" button or menu function that will force the monitor to try to better adapt to the video card's sync rates.  The result of the auto-sync should place the entire picture "on-screen" without any shifting, expansion, or compression.  Some monitors do a great job of this and other monitors make the picture worse.  Either way, you should be able to "fine tune" the adjustments after the auto-sync is performed using the geometry controls.  Once set, most monitors will "remember" the settings for any particular mode and re-use the settings once that mode is re-engaged preventing the need to re auto-sync each time you switch modes.

If you're using a full "digital" connection to the monitor (usually with a DVI cable), then you don't have to worry about sync rates as the video card has a 1:1 relationship with the monitor and controls each pixel directly.  If you have a video card with a DVI connector, than I *STRONGLY* recommend that you get a monitor with a DVI input - the picture quality is *MUCH* better (no analog loss) and you don't have to worry about sync rates.  If you have a monitor with DVI, but your video card doesn't, consider upgrading your video card.

BTW, while in a Command Prompt (or DOS), you can also use "alternate" text modes to view more text on-screen.  With a full-screen Command Prompt (or booting into DOS only), you can switch to 80x50 mode.  The DOS command is:

  mode con: lines=50

If you're in a Command Prompt Window, then you can specify any number of lines - just realize that the font size will limit exactly how many lines you can actually see in that window.  For reference, 80x50 is the mode most Linux distro's use for the boot text.  You can also use 80x43 which is an older standard - font will be the same, but you get the extra 7 lines at the bottom of the screen.

>>> KD7JYK wrote:
The monitor is large enough that even a window on the desktop is large than most monitors, how can I get these programs to operate within a window, rather than switch over to a dedicated full DOS screen?

>>> My reply:
The magic keystroke you're looking for is...

   <ALT><ENTER>

Pressing <ALT><ENTER> in a Windows Command Prompt will switch between windowed and full-screen modes.  In some situations, the setting is saved so the next time you launch the app, it starts in whatever mode you last used.  Otherwise, you need to edit the properties of the DOS app's shortcut to launch in Windows or full-screen mode to make it "permanent".

I hope I read the problem correctly and answered appropriately.  If not, post again and let's see if we can sort it out.

73,

  - Aaron, NN6O