NTSC or PAL?

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Lee1978
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NTSC or PAL?

Post by Lee1978 » Fri Oct 16, 2020 11:51 am

Hi guys, is there a simple way to tell if a ROM file is NTSC or PAL?

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Bregalad
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Re: NTSC or PAL?

Post by Bregalad » Fri Oct 16, 2020 2:54 pm

A ROM file is just the dump of a PRG-ROM chip (possibly a CHR-ROM chip too) with some iNES header added to it. It's inherently neither NTSC nor PAL, just data.

NES2.0 header allows to set NTSC or PAL in the header.

ROMs from the GoodNES set have the game region between parenthesis.
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Quietust
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Re: NTSC or PAL?

Post by Quietust » Fri Oct 16, 2020 3:06 pm

To further clarify, NES programs fall into multiple categories:

1. Programs which are designed for one region but which happen to work just fine in other regions. Most NTSC games fall into this category, and some of them have specially modified PAL versions which also fall into this category; running the game in the wrong region typically results in gameplay/audio being too fast/slow and audio being off-pitch.
2. Programs which are specifically designed for one region and malfunction if run in the wrong region. This mainly consists of games that use cycle-timed raster effects - Battletoads is the first one that comes to mind.
3. Programs which are designed to run in multiple regions, using special code to detect the machine's timing and adjust their behavior accordingly.
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Lee1978
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Re: NTSC or PAL?

Post by Lee1978 » Fri Oct 16, 2020 3:51 pm

Thanks for the replies, that helps a lot. I also discovered that mesen shows the video format when booting each Rom which is useful.
I’m in the UK so have PAL hardware, if I understand correctly many NTSC Rom files may well work but it’s unlikely they’ll work properly due to the differing frequencies? Unless they have programming which allows for both formats, is that correct?

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tokumaru
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Re: NTSC or PAL?

Post by tokumaru » Fri Oct 16, 2020 4:25 pm

Lee1978 wrote:
Fri Oct 16, 2020 3:51 pm
Thanks for the replies, that helps a lot. I also discovered that mesen shows the video format when booting each Rom which is useful.
I think Mesen has a database of ROMs, meaning it will recognize the ROM you're opening (as long as it's in the database, which's not often the case with hacks and homebrews) and select the appropriate mode for it. If it's not in the database, you'll have to rely on the header or on manual selection.

Like it's been said before, there's nothing about an NES program that locks it to a particular video format or region, making automatic detection impossible.
I’m in the UK so have PAL hardware, if I understand correctly many NTSC Rom files may well work but it’s unlikely they’ll work properly due to the differing frequencies?
Depends on how much the program relies on the timing of the hardware. Gameplay and music will be slower than in an NTSC console no matter what, since NTSC consoles are always 60Hz and PAL consoles always 50Hz. The pitch of the music will be wrong too, because note frequencies are based on the CPU speed, which differs between NTSC and PAL. None of this is game-breaking, though. However, if the game relies on the clock speed for visual effects (status bars, parallax scrolling, etc.) those will be timed incorrectly, and could render games unplayable.
Unless they have programming which allows for both formats, is that correct?
Very few games were optimized for both PAL and NTSC back in the day. I can't even think of any examples. Recent homebrews are more likely to behave this way.

tepples
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Re: NTSC or PAL?

Post by tepples » Fri Oct 16, 2020 7:10 pm

If I remember correctly, Codemasters games were optimized for both NTSC NES and PAL NES.

Pokun
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Re: NTSC or PAL?

Post by Pokun » Mon Oct 19, 2020 6:34 am

If you play on a PAL NES, you should play the PAL versions of games as much as possible, and hope that they have been PAL optimized.
Many released games weren't optimized though and will always be too slow even if you play the PAL version. Many others are half-way optimized and will still have the wrong sound tempo, pitch or have other speed problems. Such is the life of us PAL people (or you can import a Famicom like me, and play the NTSC version of games).

There are a few PAL-exclusive games that belongs in the second category that Quietust listed. Elite comes to mind, it's unplayable on any NTSC machine (Famicom or NTSC NES).

Found a list of some games that are or are not PAL optimized in their PAL version.

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za909
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Re: NTSC or PAL?

Post by za909 » Mon Oct 19, 2020 7:17 am

Asterix also comes to my mind as a PAL-specific game. This is because in the PAL region there's a much longer VBlank period, which allowed more VRAM updates per frame. Some games used this extended budget, and this makes them absolutely incompatible with NTSC consoles.

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