Which way are scanlines supposed to go when in Tate mode?

[chanunnaki]

I'm pretty sure that scanlines always go horizontally when in normal orientation because that's how the electron gun moved, from top to bottom, but when you turn the display on its side, i.e. tate mode, it doesn't change the orientation of the electron gun, right? Meaning if I turn the display 90° clockwise, the gun would scan from the right to the left, therefore the scanlines would run vertically in tate mode. That is my understanding. I don't recall ever seeing an original DK arcade cabinet or any other Tate arcade game for that matter, so could someone shed some light on what is the most accurate way to represent the scan lines in Tate mode?

[thorr]

The scanlines rotate when the screen rotates. Take a TV and tip it 90 degrees on its side. It doesn't change the way it draws the scanlines all of a sudden because it is on its side.

[J3RK]

Arcade monitors weren't (at least typically) custom made to function 90 degrees from normal. They were simply turned 90 degrees as mentioned above. So the direct answer is that when simulating them, they should go vertically.

[limi]

Indeed, and that’s also why there is a separate default INI setting for vertical cores, vfilter_vertical_default.

[lagerfeldt]

If you have a digital screen that can pivot (rotate 90 degrees in either direction) then the scanlines should be horizontal and you simply physically rotate the screen. This will look exactly like it's supposed, as if a CRT was rotated in an arcade machine.

If the orientation of the core isn't correct by default then make sure it's oriented vertically in the core options to fill out as much of the screen as possible, as it would have been in the arcade.

You have a digital screen, usually a TV, that can't pivot then you need to keep the core orientation upright in the core options. This will lead to large pillarboxing, i.e. black borders on each side. Only in this case would it make sense to change the orientation of the scanlines.