HW Video Rotate for Msx1

By andrea.denara

Expert (67)

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11-07-2014, 11:59

I've seen game "Destroyer" and I've got an idea.
Is it possible to add a switch to rotate video (90 degrees)? A switch that invert axis direct after VDP and before other video circuits.
I'm not HW specialist but I think VDP is connected to a circuit that decode video signal and maybe exist the possibility to invert xy axis (if VDP output got 2 signal (XY) to the subsequent circuit).
Think about the advantages, 32 sprite in line, Horizontal scroll (1 pixel step) without limitations in colors.
Graphics will change from 256x192 to 192x256 but think about many C64 games that are 160x200, so 192x256 can be good enough for many games.
I think game like Pac Land, Mario and others that have Horizontal scroll.




Enlighted (6499)

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11-07-2014, 17:46

andrea.denara wrote:

Is it possible to add a switch to rotate video (90 degrees)? A switch that invert axis direct after VDP and before other video circuits.


By Maggoo

Paragon (1212)

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11-07-2014, 20:14

Off course there is a hardware solution LOL!

By Daemos

Paragon (1940)

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11-07-2014, 20:18

It is possible but it takes simply too much effort to be done. The VDP itself cannot be made to do something like that so an extra circuit is required that does the rotation. First, someone has to design the circuit and wire it to the video output of the VDP next the circuit needs to be optimized to fit inside the MSX and not use too much power to bog the whole PSU down. Then people need to get interested in this modification and take time and effort to solder the print in and install the switch which is something not likely to happen. Finally, software developers need to take interest into the modification to actually start designing software for this special mod.

All these things are very unlikely to happen unless someone is willing to do all the steps by himself and prove the awesomeness of the modification pulling other people into the mass effort of doing this.

I don't think all of this is ever going to happen.

By hit9918

Prophet (2899)

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12-07-2014, 20:48

@andrea, I too dreamt of that, but if you look for example at the MSX2/SNES mario gras tile, it would not be possible on a rotated screen. The world often is a sandwitch.

The sprites, "max 4 sprites above each other" Smile
Often one would prefere that, but again a sandwitch example, a sonic which needs many sprites per column:

With variable height sprites (sort by Y+height) the MSX1 makes similar linecolor things.
I can think of an epic mario with 2 sprites per scanline, but a lot sprites stacked above each other.
hair, face, suit blue and red, white gloves, shoes, a sandwitch from top to bottom.

On a rotated screen that mario could not display even when he is alone on the screen.

By brawaga

Resident (42)

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25-02-2021, 14:19

What is the problem to physically rotate the display?


Enlighted (5741)


25-02-2021, 15:26

andrea.denara wrote:

I've seen game "Destroyer" and I've got an idea.
Is it possible to add a switch to rotate video (90 degrees)?

Yes... This guy has done it.

By albs_br

Master (248)

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25-02-2021, 16:05

There is a Doom port for Atari 2600 (!!!) that works with the TV phisically rotated 90º. As the machine works with lines and raycasting engines are column-based, it's a very clever approach.

By Grauw

Ascended (9753)

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25-02-2021, 17:44

Something like that would need a full frame buffer if done after the VDP. Like a Framemeister or OSSC Pro offer. In fact it is explicitly called out as one of the features the OSSC Pro will have:


That’s not all, with a full frame buffer all kinds of processing can be done. Have an older arcade game that needs a monitor in portrait orientation? In framebuffer mode, OSSC Pro can rotate the image for you, allowing you to play such a title without having to figure out a way to rotate your giant HDTV, or lie on the floor on your side.

However, since the image is 4:3, it will introduce thick letterbox borders.

By andrea.denara

Expert (67)

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25-02-2021, 17:57

I meant something that could swap axes via hardware. Not the physical rotation of the screen