MSX1 Overscan

Well, as this is a PAL version, theoretically, a PAL video source can be combined with it but, if an NTSC or PAL 60 video is fed into it, then VDP goes nuts and shows more vertical resolution than it should.

When applied, an extra third of character lines is shown in the upper part of the screen. I think there are 8 chars lines, but I was only able to see 6.5 chars lines.
The lower third of the screen is cut somehow. I was able to see 7.5 chars lines with a CRT screen, but only 6.5 on TFT or LED screens.
Regarding VRAM arrangement, the "extra" third of character lines starts just where the bottom third stops, the color table, pattern table and so, so it overlaps with sprite working area.
I had to re-map the VDP registers in order to get a usable VRAM structure.

Here are some pictures.
The first one is overscan in SCREEN 2, VDP registers reconfigured, so using only 1-pattern bank.
Numbers on the left are the picture from an MSX2 composite video set to 60 Hz.
The black sprite is show by mistake. It is not an issue of this mode nor the VDP registers set.
On the second one you can see the register set I did. This is only an example.
The third picture is a CRT screen. The green line on the left is my MSX-2 set to 60 Hz.

In the third picture, some text is shown in the bottom lines. It is part of the text from the function keys.
I think it is around half a line, so in the lower third 7.5 lines are shown, so giving a total of 240 lines.
Other monitors only show 6.5 lines, so only 232 lines.

Neat!

But I guess not practically usable on regular MSX1s without feeding in a different frequency superimpose signal?

@graw:
You are right.
I am not 100% sure about the Pioneer internals, but i guess that feeding a regular PAL 60 Hz sync signal into rhe VDP can do the trick.
NTSC is not suitable, as some monitors detect the resulting signal as NTSC, so showing MSX graphics as black and white.
I wonder if there is a simple sync generator that is able to generate proper sync...
I wonder if there are more frequnecies accepted and how the VDP could react to them...

These are the displays I have now.
I also have a plasma display in another floor, but it is gigantic and too heavy. I do not think the results can be different.