ACA500plus with Indivision ECS (2015/v1) and ECS Agnus - Does it allow soft switching between PAL and NTSC?

Xebec · Nov 15th 2021

Hi there!

I have a NTSC Amiga 500 Rev 5A with 512KB of C= trapdoor memory, the ACA500plus, ECS Agnus (i.e. 1MB chipram working), and Indivision ECS (~ 2015 - I believe rev 1). I'm using a multisync VGA monitor with this Amiga.

I see the boot menu for ACA500Plus has "Force PAL mode" at boot. Is that only for the screen output, or is that actually changing to PAL mode for software too?

The music for Frontier sounded a little too fast when I tried various PAL options so I wasn't sure if it was possible to soft-switch on A500 between NTSC and PAL with this hardware configuration?

Thanks!

John

P.S. I'm haven't panicked, and my hands are washed.

Jens · Nov 15th 2021

Quote from Xebec

I see the boot menu for ACA500Plus has "Force PAL mode" at boot. Is that only for the screen output, or is that actually changing to PAL mode for software too?

It's actually switching to PAL mode, but still using the NTSC crystal, which swings about 1% faster than the PAL crystal. You should not notice this in terms of speed, but if you're a musical person, you might hear a difference in pitch.

Quote from Xebec

The music for Frontier sounded a little too fast when I tried various PAL options so I wasn't sure if it was possible to soft-switch on A500 between NTSC and PAL with this hardware configuration?

I'm pretty sure that you didn't hear the difference in pitch, and the difference in speed is most likely due to the nature that the beat timing is generated for most Amiga-mods - that's usually tied to the vertical blanking frequency, so any beat frequency is tied to 50Hz for PAL or 60Hz for NTSC. This results in NTSC-sourced beat speeds to have a wider selection of speeds due to the higher source frequency (the beats per minute always need to be a whole-number division of the vertical blanking frequency). My guess is that when the title was converted to the other video mode, they just chose something that was "close enough" to the original speed, as an exact match was just not available. Just a guess, though - only the authors can tell for sure.

Quote from Xebec

P.S. I'm haven't panicked, and my hands are washed.

Yeah, that message. Tobias introduced it during the first Covid-19 lockdown. Now we're in the middle of the 4th wave, and it's more up to date than ever. Let's not talk about that..

Xebec · Nov 16th 2021

Very cool that the ACA hardware can enable PAL mode on A500s that (google says) appear to usually need jumper changes or other items.

Yes I should have clarified - pitch was OK, but the beat or hit of each instrument definitely seemed to be occurring at a more rapid tempo than it should have. I’ll do some testing in emulation or on my A1200 to see if I can get it to time better via various settings/screen resolutions.

Thanks for the great products and support!

Jens · Nov 16th 2021

Quote from Xebec

Very cool that the ACA hardware can enable PAL mode on A500s that (google says) appear to usually need jumper changes or other items.

Google ist not always right. And the ACA500plus has introduced a few things that were thought to be impossible from the external connector before. Yes, it's retro-computing, but no, it's not stuck in the 1980s (in other words: There is development going on, and new ideas are applied).

Quote from Xebec

see if I can get it to time better via various settings/screen resolutions.

"better" implies that you've had a "worse" experience so far. What I was trying to explain yesterday was that technical limits have most likely lead to an intentional speed change with the move to a different video mode. So technically, you can't speak of "better" or "worse", because it's just the way the authors have created it. The best words that come to (my) mind are "original" or "un-altered", which probably triggers an "unusual" feeling in you, as it deviates from what you remember hearing as a kid. I have that same feeling when I hear a tune played back on an NTSC machine, because I grew up in Germany, where PAL used to be the norm.

Xebec · Nov 16th 2021

Quote from Jens

Google ist not always right. And the ACA500plus has introduced a few things that were thought to be impossible from the external connector before. Yes, it's retro-computing, but no, it's not stuck in the 1980s (in other words: There is development going on, and new ideas are applied).

"better" implies that you've had a "worse" experience so far. What I was trying to explain yesterday was that technical limits have most likely lead to an intentional speed change with the move to a different video mode. So technically, you can't speak of "better" or "worse", because it's just the way the authors have created it. The best words that come to (my) mind are "original" or "un-altered", which probably triggers an "unusual" feeling in you, as it deviates from what you remember hearing as a kid. I have that same feeling when I hear a tune played back on an NTSC machine, because I grew up in Germany, where PAL used to be the norm.

Sorry I should have used better English re: "better" and "worse" experiences. I agree completely with your response here.

What I mean is, the music "beat timing" sounded fast to my ears, but I also realize it might actually be timed correctly. I want to try some different modes (I'll use my A1200 later today) to see if the speed changes vs. my ears to see if it's just me or something else going on. I think you're right but want to know 100% for sure by trying a few things. Perhaps it's just getting older so I'm expecting things to be slower ;-).

And yes ACA500plus is an excellent piece of kit - personally I don't see the need for additional acceleration beyond this on an Amiga 500 - a 42 MHz 68000 with fast ram is quite powerful for the software library.. though it's nice to have options.