How to set typesetting area in virtual consoles smaller than monitor screen?

Hi to experts,

I am again facing the same problem after I upgraded
openSUSE-13.2 to LEAP-42.2, although I did this at earlier
upgrades somehow - but just how? - got the sentence mirror
of the virtual (only text) consoles ttyX in such a way that
black bars are formed all around.

Please refer:
http://www.guenzl.net/privates/rand.jpg
It has black bars around the sentence mirror (the text area).

This worked so far only with the proprietary NVIDIA driver.
It is now re-installed at Leap-42.2 and works perfectly.

Here’s how it looks “normal”:

http://www.guenzl.net/privates/ohne_rand.jpg

So I am NOT concerned with the reduction (change) of the
characters, but only of the writing mirror, the typesetting
area (smaller than the monitor screen).

Is an HDMI connection between PC and monitor necessary?

How had I managed this? I do not know it anymore.

Thanks for help,
Werner.