43 text rows is related to EGA: 8-scanline font * 43 rows ~= 350 scanlines. This isn't to say VGA can't do 43 rows; it can, it's just that the video hardware must also be reconfigured for a different number of scanlines.

50 text rows is related to VGA: 8-scanline font * 50 rows = 400 scanlines.

Point being that you'll probably be as happy with 50 rows that is more native to VGA as with 43 rows that is more native to EGA.

In the post here you will find a number of small programs that can set a variety of DOSBox's built-in text modes, such as 80x50, 80x100, 132x43, 132x86. Your application should be able to adapt to at least the 80 column modes.

Thanks for this. I will have to try some of these options. dBase III+ is from the mid/late 80s, and was designed for EGA rather than VGA. If it sees a 50 text line display it switches back to 25 line display. Only 25 and 43 lines are supported. I'll let you know what happens!

Well, if it really is that picky, here's what you can do: set machine=ega in DOSBox and run the 80X50.COM program (it just loads the 8x8 font patterns, which in VGA results in 50 rows, but in EGA results in 43 rows).

On a side note, FoxBASE+ > dBASE III+ 😉

Might work if the VGA is switched to 350 lines emulation.

h-a-l-9000 wrote:

Might work if the VGA is switched to 350 lines emulation.

It works for the most part, but with one small "issue".

When switching from 400 to 350 lines emulation in VGA and then loading the 8x8 font, you get 43 text rows, but the display remains at 350 lines, so there are 6 unused lines at the bottom of the display.

When using machine=ega and loading the 8x8 font, you get 43 text rows, and the display changes from 350 lines to 344 lines, without the 6 unused lines at the bottom.

Worked perfectly! I used machine=EGA and Scanres/80x50. Some wasted lines at the bottom but nothing to moan about. I had to change 2 out of 10,000+ lines of code to overcome differences in the way environment variables are handled. Pretty impressive!

The only downside so far (other than the small font) is the lack of speed. It runs at about the speed of a 386 on my 2.1Ghz laptop - but I can live with that as the price of running 23 year-old software on an OS that is designed to stop it running at all!

A zillion thanks to all those who talked me through this problem.

Longsoft
"Sleepless in Southampton"