Amiga questions you've always been too embarrassed to ask

[NLS]

Probably all of them.
(of those already happened by the time of pre-release)

[Gordon]

Why did some Amiga 1200 motherboards have detachable mouse ports?

[ajk]

This is just a guess, but most likely it was to make the board a little bit smaller and therefore cheaper to manufacture. The little mouse port PCB was perhaps nested in the empty space where the accelerator would go, and in later models replaced entirely by just a connector and cable.

[Daedalus]

Yep, that's most likely it. PCB manufacture is generally costed on the rectangular footprint of the board. On the A500, they put the A501 PCB in the space left by the trapdoor, and on the 1200 they originally seem to have put the RTC expansion there. When that didn't become a big thing, it made sense to move it to that space instead. That was with the 2B boards, though the board was initially made shorter for the 1D4 boards with the mouse port on a cable. (It was also apparently planned for prior revisions too, since they have the pads for the internal connector). Presumably the cost of the cable assembly was more than the PCB assembly...

Edit: You can actually see this by looking at the PCB layout of the 2B motherboard on http://www.amigapcb.org/ (can't link directly to it, but you can select A1200 2B and see both the mouse port PCB and the proposed RTC expansion in the space at the bottom right of the board).

[d4rk3lf]

Ok, so we got PAL (25fps) for Europe, and we have NTSC (29fps) for U.S. as a TV standards.
Yet, there are a 50 fps Amiga games, and we feel they are smoother opposing to games with 25 fps.
How and why do we feel difference if TV is "locked" to 25 fps?

[Ian]

pal is 50 FPS NTSC is 59.97 or something just shy of 60 FPS.

Games running at 25/30 are updating half the available frames.

So will appear less smooth as there are less updates between movements.

[ajk]

The analog television signal is interlaced. This means it's 25 frames per second, but 50 fields per second (or 30/60 in North America). A field is one half of a frame, either the odd or even lines.

Back when TVs were first made, it was noticed that 25 Hz would be too flickery, but there was not enough bandwidth and processing capability to transmit 50 frames each second at a good resolution. So, only one field was updated at a time. This gives the illusion of both relatively high resolution when the picture is static, but also smooth motion when it is not.

Most games on the Amiga use a low resolution such as 320x256, essentially one field, so even though technically they run at 50 fields per second, it's pretty much the same as 50 low resolution frames per second.

[demolition]

Originally Posted by ajk

Most games on the Amiga use a low resolution such as 320x256, essentially one field, so even though technically they run at 50 fields per second, it's pretty much the same as 50 low resolution frames per second.

Not just 'pretty much', but exactly the same. When you keep transmitting the same field, one field equals one frame.

[ajk]

Yes, only apart from the terminology. From the TV's perspective having just odd or even fields coming in is unusual and some devices might have issues with the signal (I've had some older LCD TVs and also capture devices get quite confused ).

[d4rk3lf]

Thanks guys.

[malko]

Luca's adventure games are based on SCUMM.
In terms of the SCUMM engine, is there a big difference between the available Amiga games (Zak McKracken, Maniac Mansion, Loom, Indy III, Indy IV, Monkey I, Monkey II) or is it the same engine ?

[NLS]

Same engine.

[Jope]

Each engine was specifically built for that game. They share some common code, but are not interchangeable.

[Nightshft]

Do you know ScummVM? It's a Scumm Engine (Virtual Machine) that runs on Windows, Linux but also many other platforms including some gaming-consoles and AmigaOS4. It just uses the data-files of the games and is able to play most of them. There also is a compatibility list on their homepage.

[malko]

Originally Posted by NLS

Same engine.

Originally Posted by Jope

Each engine was specifically built for that game. They share some common code, but are not interchangeable.

1-1... It doesn't help much

Originally Posted by Nightshft

Do you know ScummVM? It's a Scumm Engine (Virtual Machine) that runs on Windows, Linux but also many other platforms including some gaming-consoles and AmigaOS4. It just uses the data-files of the games and is able to play most of them. There also is a compatibility list on their homepage.

Yes, I know scummVM even if I never tried it seriously. But scummVM requires quite a nice config to run a game. In the opposite all of the mentioned games are runnable on an OCS/ECS Amiga.
Thus my question, was the engine the same (evolution excepted). I mean if we took the last engine (let's say Indy IV) could it be used to run previous game ?

[DamienD]

I think these all use the same older engine:

... Indiana Jones And The Last Crusade: The Graphic Adventure
... Loom
... Maniac Mansion
... The Secret Of Monkey Island
... Zak McKracken And The Alien Mindbenders


Whilst these use the newer engine:

... Indiana Jones And The Fate Of Atlantis: The Graphic Adventure
... Monkey Island 2: LeChuck's Revenge

[davide78]

According with the Italian Wikipedia Entry on SCUMM there are 9 versions of the engine.

Amiga games used versions from 2 to 5:

Version 2:
... Maniac Mansion
... Zak McKracken And The Alien Mindbenders

Version 3:
... Indiana Jones And The Last Crusade: The Graphic Adventure
... Loom

Version 4:
... The Secret Of Monkey Island

Version 5:
... Indiana Jones And The Fate Of Atlantis: The Graphic Adventure
... Monkey Island 2: LeChuck's Revenge

Oddly, the Wikipedia english entry does not report the information on the different versions.

[meynaf]

Originally Posted by malko

Thus my question, was the engine the same (evolution excepted). I mean if we took the last engine (let's say Indy IV) could it be used to run previous game ?

The engine is more or less the same, but changes from one game to another make it unsuitable to run anything but the game it came with.

You can try replacing the data files of one game with another if you want : the game won't even start properly. Even if it seems to be the same engine revision (e.g. Loom can't play Indy3).
There are also changes in data files layout which makes some versions completely different (small xx.LFL vs larger files).

ScummVM has to know which game it is to be able to load it.

[malko]

Thanks for your answers guys

[nogginthenog]

Originally Posted by Nightshft

It's a Scumm Engine (Virtual Machine) that runs on Windows, Linux but also many other platforms including some gaming-consoles and AmigaOS4.

No Amiga OS3 port? That's a shame. I was involved in the Sarien project many years ago which was merged (I think) or at least replaced by Scumm.

I guess it's because there is no maintainer. I should really fix that