View Full Version : EGA 43 rows on monochrome

March 13th, 2010, 06:35 PM
Using a Paradise autoswitch EGA 2 v3 I was able to get 43 rows on an amber monochrome monitor using the extended EGA text modes. Actually it looks really sweet and I have a screen shot. It is connected to an XT and showing a vt102 terminal to my linux server using a null modem cable.
Just put this in your .bashrc (or .bash_profile or /etc/profile I think (I use debian) if you use bash:

# for serial console to display 43 rows 80 columns EGA
if [ "$tty" == "/dev/ttyS0" ] ; then
stty cols 80
stty rows 43
export COLUMNS=80
export ROWS=43

If you are using Telix you need to go to the screen options and set it to EGA 43 rows. Also for DOS use there are EGA programs for changing the rows to 43 called "EGA43.COM".

Oh and since the picture was taken in the dark I had to bump up the contrast and brightness to get it close to what it looks like in real life... it looks even better than the picture.


March 13th, 2010, 07:31 PM
Looks like an 8x8 font. Let's do a little back-of-the-envelope:

A normal MDA text display is 25 lines, where each line is 14 rows (25x14 = 350 lines).
If you use an 8x8 font, you can fit in (350/8) = 43.75 lines.

Jjust about any EGA capable of producing MDA output can do this. In fact, if you replace a plain-Jane MDA character generator ROM with one from a CGA, you can do this simply by reprogramming the 6845 registers.

The downside is that you ge no spacing inbetween rows. (write a row of uppercase "T" followed by a row of lowercase "p" and you'll see what I mean).

38 rows might be more readable, using a 9 row high character box.

March 13th, 2010, 08:40 PM
The downside is that you ge no spacing inbetween rows. (write a row of uppercase "T" followed by a row of lowercase "p" and you'll see what I mean).
Just the same as 50-line mode on VGA.

Even the original IBM MDA could do 43-line mode if it had enough video RAM, but its 4 KB is only enough for 80x25. A Hercules-type card with more onboard RAM should do 43-line mode just fine, although I haven't tried it.

March 13th, 2010, 09:19 PM
I didn't say that all 43 lines would be different. :razz: You could probably patch some additional RAM and some "glue" to expand the memory to 8K, but it wouldn't be worth the trouble.

I haven't looked at the vanilla Herc card to see if the text-mode RAM is expandable to 8K, although I doubt it without cuts and jumpers.

More text-mode RAM would break one feature--the ability to wrap-around the address space, to allow for fast scrolling (about the only way to keep up with 9600 bps data in terminal mode).

But I'll have to review my notes on the Herc Plus--it probably will allow a larger display RAM window.

There were some enhanced EGA modes that were tantalizing, until you actually had to use them. 50 line x 132 characters was perhaps the most unreadable text display I've ever seen.