Why is the Amiga display not centered?

[edd_jedi]

I'm pretty sure it's the games as opposed to the TV, it's the same on my other large LCD screen, and most games and Workbench are, as you say, not centered.

If you look closely at the Lemmings screenshot you can see that the 'border' is still there, it's just been manipulated. Sensi has obviously found a way around it (overscan?)

This is why I believe this was a deliberate software configuration (by AmigaDOS perhaps?) to cater for old, round screened CRT TVs.

[Bamiga2002]

My display is also right-oriented, just a little. But it's still noticeable.

[edd_jedi]

Just thought I'd post another observation on the subject. I was playing Road Rash, and as you can see although the off-center main display is there, you can also see that the gradient background goes outside of the bordered area.

I'd be very interested if anybody understands why this border is there, and how certain games manipulate it or even get around it completely (see above.)

[Amiga1992]

Copper banding usually goes all over the screen area into overscan, this is why you see it exceeding the regular play screen. It's like on the C64, the "border" is a special area you access differently.

My guess is, and knowing not much about coding, is that the way copper banding works (or, at least, the way is implemented here), it affects all the screen memory on that bitplane, filling even onto the overscan with color data.

[Leffmann]

Originally Posted by edd_jedi

I'd be very interested if anybody understands why this border is there, and how certain games manipulate it or even get around it completely (see above.)

The Amiga display hardware is pretty flexible. You're not bound to 320 or 640 pixels across, you can widen or narrow it as you wish.

[Amiga1992]

I was just playing Fire & Ice CD32 and it has a ridiculous amount of border on the left side. Looks absolutely ridiculous.

[dlfrsilver]

on the very latest winuae beta, the border bug is once again here...... it shows up bugs which are not appearing on the real hardware (no matter the display being centered or not).

Look here :

[AmigaFriend]

Originally Posted by Akira

I was just playing Fire & Ice CD32 and it has a ridiculous amount of border on the left side. Looks absolutely ridiculous.

You just have to move your TV set a little bit to the right. IT will be perfectly centered.

Jokes aside indeed that is a fair chunk of black unused space.

[Toni Wilen]

Originally Posted by dlfrsilver

on the very latest winuae beta, the border bug is once again here...... it shows up bugs which are not appearing on the real hardware (no matter the display being centered or not).

Look here :

Not this again. It happens on real hardware. Get a monitor that has less overscan and you'll see it, everyone with 1081 or similar monitor has seen this with A500 demos!

[dlfrsilver]

indeed, but you can only saw them if the screen is not correctly setted (it's like winuae display is larger that a real amiga screen, in fact it should stay hidden.

[roy bates]

on a crt monitor the the height and width is adjustable to fill the screen and i still remember when i had a 1084s from new and adjusting this to fit the screen with no borders.(and the centering of the display)


its pretty much impossible on lcd screens.

[TCD]

Originally Posted by roy bates

on a crt monitor the the height and width is adjustable to fill the screen and i still remember when i had a 1084s from new and adjusting this to fit the screen with no borders.(and the centering of the display)

Same here with my 1084. I don't actually see how this can be 'fixed'. Maybe changing the connection type to the TV? Otherwise it seems impossible to fix the problem without adjusting the TV.

[LocalH]

Originally Posted by dlfrsilver

indeed, but you can only saw them if the screen is not correctly setted (it's like winuae display is larger that a real amiga screen, in fact it should stay hidden.

I'm with Toni. If real Amigas output that, but the display device doesn't overscan enough to show it, then WinUAE should output the same thing before any filtering/shaders/overlays. Emulators should always emulate the full signal output, borders and all. This is what pisses me off about most console emulators (and some computer emulators), that they don't show any overscan area at all. It's not accurate and thus wrong.

[roy bates]

Originally Posted by TheCyberDruid

Same here with my 1084. I don't actually see how this can be 'fixed'. Maybe changing the connection type to the TV? Otherwise it seems impossible to fix the problem without adjusting the TV.

i dont think it can be fixed unfortunatly.

[Toni Wilen]

If full overscan is not visible by default, then everyone would complain that (for example) The Settlers' screen is clipped.

[Amiga1992]

Originally Posted by dlfrsilver

indeed, but you can only saw them if the screen is not correctly setted (it's like winuae display is larger that a real amiga screen, in fact it should stay hidden.

What? No man, you are wrong. This is part of the overscan, and as such, the full display of the Amiga.

You cannot account for ridiculousness like mechanical monitor size and centering settings, are you crazy? Make yourself a filter that eliminates teh overscan area and be done with it. This isn't ab ug.

Now, get back on topic.

[dlfrsilver]

indeed, i have finally made a filter to correct this it's the best of both worlds

[andreas]

Originally Posted by Akira

What? No man, you are wrong. This is part of the overscan, and as such, the full display of the Amiga.
...

Now, get back on topic.

Good idea.

Originally Posted by Akira

On a REAL Amiga, the picture sways to the right of the monitor. It happens on an LCD TV through RGB, it happens on a monitor through Composite and it happens on my scandoubled display on a 14" VGA CRT.

Short answer: True.
So from eab old-schooler to eab old-schooler, let me put up a challenge for everyone: :
(Note: You cannot make (nor pass) this test with only an emulated Amiga within reach. Sorry.)

1. Have a REAL Amiga ready, preferably an A500 with 1084|1084S color monitor.
2. Boot with original Workbench and adjust H/V centering/stretching so that it's perfect once and for all.
3. Take 20-25 games of your choice on real floppy disk (preferably jump 'n runs, or shoot-em-ups, i.e. those known to hammer the Amiga chipset, like "Battle Squadron") and boot them, one after another. (Optionally test-play them, but that's according to your free will)

Prove me wrong what I'm going to say now:

From all 20-25 games, you will not achieve the goal of having a centered picture with all of the games without "player's intervention". Once in a while, you will have to touch the H/V centering and/or H/V stretching knob(s) of the 1084 even though you would refrain from doing so.

Happy proving!
(My assumption is that on real hardware, it will be hard for you guys to prove me wrong. Simply because I clearly do remember having to tweak the screen specs all the time with different programs/games on my 1084 (thomas said it before, IOW). Having them set to the same values for 1-2 weeks was exceptionally rare, since soon there was one game that would be special again and needed to get its H-stretching adjusted at least a bit. For an Amigan, a broken V- or H-stretching knob on his monitor is utterly a catastrophic situation .)

[rare_j]

Originally Posted by Toni Wilen

If full overscan is not visible by default, then everyone would complain that (for example) The Settlers' screen is clipped.

+1 This is a really good feature of WinUAE.

A game that i noticed uses the full width of a CRT TV really well is Exile.
I dont have real hardware to hand anymore but it would be interesting if that game is intentionally shifted left to compensate.

[Amiga1992]

Andreas is absolutely right and proves the point. I had to tweak the monitor many times depending on the game, trying to make it occupy as much of the screen and be centered as much as possible.

Now I wish LCD TVs had these functions, because my CD32 certainly looks ridiculous.