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Changing the Aspect Ratio

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First post, by Andrewb

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I realise that DOSbox targets gaming software and that the answer to the following enquiry may well be "can't do that, won't do that" but I ask in hope. Even a confirmation that "it can't be done" will save me wasting any more time looking for a solution.

I'm looking for a mechanism by which I can change the aspect ratio of a DOSbox window, or cause it to change itself.

For example:

The normal DOSbox text window starts out (on my XP machine) at 646x425 pixels with a perfectly readable font.

When I run SkyGlobe, the DOSbox window magically enlarges to 646x505 (display area 640x480) to maintain the aspect ratio required for the grapical display.

When I run dBase-IV, in its VGA43 mode (43 lines of 80 columns), the DOSbox window stays at 646x425 and onscreen text is compressed (though, apart from that, it appears to run just fine).

When running dBase-IV in a CMD window, I am able to tell the CMD window (by means of the Windows properties) that I want 43 lines at my standard character size, and it duly obliges by stretching the window vertically. But with the impending move to Windows 7, I will no longer be able to run dBase in a CMD window.

Is there any mechanism within DOSbox to achieve a similar result?

I've been through the readme/manual, browsed the forum and studied the .conf options, but have so far drawn a blank. I've seen, and tested, various resolution and scaling options, but these all appear to act on the whole window to get a "bigger picture" with no obvious ability to tweak the aspect ratio.

A web search has revealed little more, except for a reference to DOSbox having some built-in "text modes". The author quoted "132x25 and 132x43 with the 16-line font", but no clues as to how to invoke them. I can find nothing about such modes in the documentation. If these exist, I can hope for an 80x43 mode that might be exactly what I need.

So, can I get a taller 43 line display and, if so, how do I do it? Or am I stuck with compressed text?

Thank you for having read this far...

Regards, Andrew.

Reply 1 of 4, by ripsaw8080

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I don't think there's a way to modify the aspect ratio of any video mode, text modes included, without changing DOSBox's source code.

Reply 2 of 4, by wd

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Try switching to 43 lines mode (there should be some small programs out there
to do that) and start dbase afterwards.

Reply 3 of 4, by ripsaw8080

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I don't think the OP is looking for how to set 43-line mode, rather for how to get more lines without changing to the smaller 8x8 font, because Windows lets you define the font and dimensions of the command window.

Here's something that might be useful. One line of code in int10_modes.cpp creates a new text video mode 0x56 in the svga_s3 machine type that has 80x50 characters, but uses the normal 16-line font, not the smaller 8-line font. It looks exactly like the standard 80x25 mode, but with double the number of lines. However, it's obviously not standard, and not all apps will adapt to it, but some will.

 { 0x054  ,M_TEXT   ,1056,688, 132,43, 8, 16, 1 ,0xB8000 ,0x4000, 192, 800, 132,688, 0   },
 { 0x055  ,M_TEXT   ,1056,400, 132,25, 8, 16, 1 ,0xB8000 ,0x2000, 192, 449, 132,400, 0   },
+{ 0x056  ,M_TEXT   ,640 ,800, 80 ,50 ,8, 16, 1, 0xB8000 ,0x4000, 100, 800, 80 ,800, 0   },

 /* Alias of mode 101 */
 { 0x069  ,M_LIN8   ,640 ,480 ,80 ,30 ,8 ,16 ,1 ,0xA0000 ,0x10000,100 ,525 ,80 ,480 ,0	},
 /* Alias of mode 102 */
 { 0x06A  ,M_LIN4   ,800 ,600 ,100,37 ,8 ,16 ,1 ,0xA0000 ,0x10000,128 ,663 ,100,600 ,0	},

Reply 4 of 4, by Andrewb

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@ ripsaw8080,

You are correct, dBase is showing all 43 lines of text, just very compressed.

Text Mode 0x56 looks interesting. If dBase is happy with it, I'll cheerfully accept a few blank lines at the bottom of the screen.

But now for the difficult bit - how do I invoke/engage Text Mode 0x56?

Is it a job for one of those "small programs" mentioned by wd?

Any suggestions?

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