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kevtris
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Hey All

Post by kevtris » Fri Nov 29, 2013 12:24 am

Hey everyone. I'm currently thinking of adding Creativision to my FPGA videogame system, and thought I'd poke around a bit on the forum and confirm a few things to see if I understand everything.

Because I'm in the US, I will be making an NTSC Creativision first and will most likely back port it later for PAL operation later on. I read that there was a rare NTSC version released in Japan, but I am unsure if there were any games released for it, or if the PAL games will work on it or not.
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MADrigal
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Re: Hey All

Post by MADrigal » Fri Nov 29, 2013 10:27 am

Hello, welcome to the forum! :)

There's no PAL and NTSC games. They're "multi-standard". Same exact ROM program.

NTSC and PAL CreatiVision's differ in the VDP only: TMS9929 for PAL, and TMS9918 for NTSC.

BIOSes are also the same in Japanese and European/Asian units. I dumped and compared them myself.
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kevtris
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Re: Hey All

Post by kevtris » Fri Nov 29, 2013 9:29 pm

MADrigal wrote:Hello, welcome to the forum! :)

There's no PAL and NTSC games. They're "multi-standard". Same exact ROM program.

NTSC and PAL CreatiVision's differ in the VDP only: TMS9929 for PAL, and TMS9918 for NTSC.

BIOSes are also the same in Japanese and European/Asian units. I dumped and compared them myself.
Hmm that's very interesting. How do the games know which system they are running on? Does it have a jumper on the PCB or does it cycle time an interrupt and then make an NTSC/PAL determination that way? Or does it just simply run at whatever speed your system is.

Without knowing the system, NTSC systems would play 20% faster than PAL systems because it's 60fps instead of 50fps. This assumes the games use the NMI for timing like on most other systems. If they just did software delay loops then yeah the games should run the same speed on both systems because the CPU always runs at 2MHz.
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MADrigal
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Re: Hey All

Post by MADrigal » Sat Nov 30, 2013 1:22 pm

> Hmm that's very interesting. How do the games know which system they are running on?

no idea actually. i dont kinow where they take the clock from: cpu, or vdp...


> Does it have a jumper on the PCB or does it cycle time an interrupt and then make an
> NTSC/PAL determination that way? Or does it just simply run at whatever speed your
> system is.

i should compare my jap and pal creativision's running the same games actually.

i'm 99% sure there arent any jumper on the pcb. i suppose the games run faster automatically.

> Without knowing the system, NTSC systems would play 20% faster than PAL systems
> because it's 60fps instead of 50fps. This assumes the games use the NMI for timing like on
> most other systems. If they just did software delay loops then yeah the games should run
> the same speed on both systems because the CPU always runs at 2MHz.

People like mobsie, carlsson and @username@ probably know the answer to your question
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