GODS intro music on NTSC AtariST

[vanfanel]

Hello there,

I have noticed that GODS intro music theme sounds wrong on NTSC Ataris.
I know GODS was a PAL release, but was there an NTSC version ever released? Is it somehow possible to make it sound correct on NTSC machines?

Thanks!

[DaveHarrison]

Hi Vanfanel,

This is all down to the TOS version being used, and easiest way that i know to get Pal software running correctly on Ntsc machines, without a rom changer board is to use a software version. I have a bootable version of TOS 1.04 on floppy, which stays in memory till a cold reset takes place. You will need to have 1 meg of ram, as it obviously takes 256kb or so of usable ram away, but Gods works fine on a 512 machine. I have tested this under emulation using a USA TOS Version and it changes the machine to 50hz and it boots God with perfect timing of the sound etc.

Here's a link for the software https://we.tl/t-ccvMtVdhbz

Cheers Dave

[vanfanel]

Thanks, Dave!

But what I would need is a version of GODS that plays correctly at 60Hz. I guess such a thing doesn't exist on the ST.

[mlynn1974]

I don't know why the music should mess up at 60Hz.

The funny thing is that GODS.MOD (from the Amiga version) uses CIA timing and not VBLANK timing.
Also the play routine on the ST uses Timer A so it should be independent of the screen refresh rate.

I only tested it with the version on Automation 476A/B. No 50/60Hz toggle on the menu.

[DaveHarrison]

I have been through every version that's available and none of them have a 50/60Hz option in them. It works fine when I use that software i posted using a UK TOS Rom on a USA TOS version, it didn't work when i used a 60 Hz to 50Hz program that i have. I was wondering what actual machine spec that Vanfanel is using, i presume it's just a 520STFM with USA TOS.

[DaveHarrison]

Just something else that i have noticed, the game Magic Pockets running with a ntsc rom does the exact same thing, when it's playing the Betty Boo sample music, it runs fast and timing is all over the place.

[vanfanel]

@DaveHarrison: I have several AtariST models, but yes, my main machine is an american 520STFM a friend brought me to spain years ago.
I also have several MiSTer setups, which provide a wonderful AtariST line implementation, and I am lately addicted to the recently released HatariB core for RetroArch because of the shaders and low input lag using Vulkan on Linux.

On both the 520STFM and the Pi4 running the HatariB core, I would prefer a version of GODS with correct music.
On the MiSTer it's not a problem because it implements both PAL and NTSC machines.

[ggn]

Short answer: The Bitmaps used TCB Tracker in most of their intros, and this assumed that the screen frequency is 50Hz, and used this for timings. When the game is run at 60Hz then the routine assumes that the samples finish playing faster than they should, and queues up new ones. This also happens when you run the same games on Falcon and TT with VGA frequencies.

The only way to fix this would be to run the tracker routine off some other timer than the VBL and program the timer to run at 50Hz. Not impossible, it's just nobody has done it yet.

[orionfuzion]

The only way to fix this would be to run the tracker routine off some other timer than the VBL and program the timer to run at 50Hz. Not impossible, it's just nobody has done it yet.

Depending on what needs to continue running in the VBL, running the tracker routine under a 50Hz timer can be complex.
If the VBL is executing timing-sensitive code (such as setting the color palette, arming timer B...) then the VBL must not be interrupted by the timer running the tracker routine.
The naive solution that comes to mind is to mask the timer in question at the start of the VBL and unmask it at the end.
But there is always a window after the VBL interrupt has been triggered and before the timer is masked, making it possible for the tracker routine timer to interrupt the VBL...
I had to solve this problem for my enhanced crack of Son Shu Shi, in order to be able to play the music modules at 50Hz on NTSC or VGA machines.
It was a lot of "fun"!
The solution was to detect on the fly whether the timer had preempted the VBL and delay its execution until the end of the VBL (which in reality meant reversing the priorities of the VBL and the timer "by software").

-- Orion

[Showaddywaddy]

Zippy's version (Medway Boys/BBC) appears to work on NCTS (US TOS), his crack intro sets 50hz. So the TCB tracker music, in the intro, plays correctly.

Or so it seems....

SHW

[DaveHarrison]

Nice one Showaddywaddy, i had a look at Zippy's version and yes it seems to be all good. Hopefully Vanfanel can test and confirm on his real hardware and thank you for finding this and well done to Zippy for his crack all those years ago.

[vanfanel]

Zippy's version works great for MiSTer and real NTSC ST indeed!
But on RetroArch/HatariB on Wayland, that doesn't quite work because RetroArch on Wayland can't change videomode on the fly, so what I would need for that is a version playing the music correctly without setting a 50Hz mode.

But its not that important because I am using a 50Hz configuration on RetroArch now anyway

Thanks guys!

[orionfuzion]

what I would need for that is a version playing the music correctly without setting a 50Hz mode.

That's exactly what GGN understood, hence his answer about the technical solution of running the tracker routine using a specific timer ("outside" the 60Hz VBL).
And I was following up his answer because this approach (which I implemented for the crack of Son Shu Shi) is a technical challenge that's more complicated than it sounds (see my previous answer).
Even if it's highly unlikely that anyone will implement this solution for GODS, it's still very interesting to talk about it in this thread

-- Orion

[Zippy]

Obviously that was fully intended and not just an oversight due to the intro being fullscreen.

[DaveHarrison]

Orionfuzion and GGN thank you both so much for your input and technical knowledge, i really enjoy reading these kind of things. Also thank you again to Zippy for his forward thinking version. Also Zippy, on many of the MB menus, the name Astronut is mentioned, would that Astronut have been someone from the Essex area ? Cheers Dave

[Zippy]

on many of the MB menus, the name Astronut is mentioned, would that Astronut have been someone from the Essex area ? Cheers Dave

I'm not sure, Astronut was someone Wurzel knew but I never met or even talked to them myself. I think they were a young guy who was supplying a few originals to Wurzel and maybe interested a bit in coding/cracking. They would have been from SE England, most likely Kent or Essex, yes.

[DaveHarrison]

Yes i think i knew him, there were a couple of guys that i met around 91/92 which at that time i had just gone to the dark side and brought an Amiga. These guys were the people that compiled the first bunch of Amiga CD's full of dms games and utils around 1995, there were 5 cd's. At first i never put two and two together, then one day we got talking about the Atari St and he went and grabbed a great pile of floppy disks to give me, including many MB discs. Think it was in 1994, they were both heading towards the PC and i brought his A1500 of him, which for the time was quite powerful with lots of upgrades, i still have it and on the desktop it says "Astronut:1992" ... He was such a lovely bloke, would do anything to help anyone.