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#108376 - 01/09/17 05:08 PM Variable size screens in MAME?
fulivi Offline
Member

Registered: 03/27/15
Posts: 17
Hi,

I've a question for someone who knows the video/rendering sub-system of MAME.
The current hp9845b driver switches between the two possible video modes (text & graphics) by calling the "configure" function of screen class and supplying the various raw parameters.
This way I get both modes to have the correct resolution and line/frame timings.
The problem is that the output window doesn't change its size between the two modes whereas in the real machines the two visible areas had different sizes. Text mode have a resolution of 720x375 pixels, its area is 23.62cm wide by 12.29 cm tall on screen.
Graphic mode have 560x455 resolution and covers a 20 x 16.25 cm area.
So the question is: is it possible to simulate something like this in MAME while keeping the timings the same as in the real machines?
I haven't investigated the question very deeply but maybe there's something in the screen class that allows the output screen to be rendered only in a rectangular "viewport" of the whole screen area.
This way I could have a 720x455 screen and draw just the text/graphic part of it, the rest would be filled with black.
Thanks for your help.
--F.Ulivi

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#108383 - 01/09/17 09:26 PM Re: Variable size screens in MAME? [Re: fulivi]
R. Belmont Offline

Very Senior Member

Registered: 03/17/01
Posts: 15435
Loc: USA
Yes, it's possible to change the complete screen parameters and have it work. The PlayStation driver can at any moment flip into any one of (256, 320, 512, 640) H x (224, 240, 448, 480) V.

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#108385 - 01/09/17 09:40 PM Re: Variable size screens in MAME? [Re: R. Belmont]
Just Desserts Offline
Very Senior Member

Registered: 05/23/09
Posts: 1558
Originally Posted By R. Belmont
Yes, it's possible to change the complete screen parameters and have it work. The PlayStation driver can at any moment flip into any one of (256, 320, 512, 640) H x (224, 240, 448, 480) V.


That wasn't the question. While the PlayStation driver can at any moment flip into any of those modes, the overall video timings are still identical, and at least in principle, should display in exactly the same screen area on the same monitor.

By contrast, fullvi is talking about changing resolutions and also changing the perceived size of the overall frame on the same monitor, which I'm pretty sure we don't currently support. We'd have to have some concept of physical emulation of a monitor, which we don't right now.

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#108386 - 01/09/17 09:57 PM Re: Variable size screens in MAME? [Re: fulivi]
anikom15 Offline
Member

Registered: 07/13/15
Posts: 30
According to your screen dimensions, they aren't exactly equal to the proportions of the resolutions, so having a 720x455 area and padding with black wouldn't give you the proper proportions.

That assumes that your screen dimensions are actually correct of course.

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#108387 - 01/09/17 10:27 PM Re: Variable size screens in MAME? [Re: fulivi]
R. Belmont Offline

Very Senior Member

Registered: 03/17/01
Posts: 15435
Loc: USA
The timings can also be changed, assuming the aspect ratio is the same.

We support Super VGA cards that can sync from 15 kHz CGA up to 31.whatever and well beyond.

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#108388 - 01/09/17 11:19 PM Re: Variable size screens in MAME? [Re: fulivi]
anikom15 Offline
Member

Registered: 07/13/15
Posts: 30
That's the thing though. According to OP the aspect ratios are different.

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#108389 - 01/10/17 12:01 AM Re: Variable size screens in MAME? [Re: fulivi]
R. Belmont Offline

Very Senior Member

Registered: 03/17/01
Posts: 15435
Loc: USA
Well, no, they're both 4:3 on the same monitor, it's just one doesn't fill as much area.

So in text mode you'd have borders top and bottom, and in graphics mode they'd be left and right.

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#108390 - 01/10/17 12:21 AM Re: Variable size screens in MAME? [Re: fulivi]
anikom15 Offline
Member

Registered: 07/13/15
Posts: 30
That makes sense to me.

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