50hz / 60hz

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Xeron
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50hz / 60hz

Post by Xeron »

In 50Hz mode, the Oric outputs a de-interlaced PAL signal (312 lines @ 50Hz, ~64 clock cycles per scanline).

When in 60Hz mode, does it output PAL60 (312 lines @ 60Hz, ~53 clock cycles per scanline), or NTSC (262 scanlines @ 60Hz, ~64 clock cycles per scanline) ?
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Post by Twilighte »

interesting question, and one i doubt even Oric Advanced User guide or Oric a Nu books would be able to answer. Unfortunately i don't have the answer myself but perhaps you might try Fabrice Frances if you can reach him.
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Post by Xeron »

I found an answer here from someone who apparently has been measuring the ULA behaviour with an oscilloscope.

Interestingly, it seems that the Oric outputs NTSC timings in 60Hz mode (264 lines according to that link, which is close to my guess of 262). This says to me that the people behind the Oric were hoping to sell to NTSC countries; it would just be a case of modifying the ROM to put a 60Hz attribute in the video buffer, and using a different RF modulator.
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Post by Xeron »

I have another question. If you have a 50hz attribute on the screen, and a 60hz somewhere else, does the ULA switch timings immediately in the middle of the frame, or is it just that the timing from the next frame onwards is set by the last attribute in the current one?
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Post by Dbug »

It's buffered.

If you start in 50hz, put a gazillion of 60hz changes; then a 50hz change, the display will not change at all.
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Post by Xeron »

OK, well, the code in the SVN now emulates the 60hz attribute correctly.
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Post by Dbug »

I seem to remember that the hardware blinking is related to the frequency, so in theory it blinks faster in 60hz than in 50hz, could anyone confirm that?
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Post by Xeron »

The blink attribute is handled by the ULA, and even though I don't have a real Oric to test, i'm 99.99999% sure it'll be faster in 60Hz mode.

The BASIC cursor is VIA timed, and should therefore remain constant.

BTW, Oriculator's timings have always been scanline based, and so the video to cpu clock timings should actually be very good in Oriculator (better than Euphoric, if the concerns raised in that google groups link are still true), and where they're out its just a case of changing a value in the source.
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Oric real HW

Post by kamelito »

Hi,

Don't you have any real Atmos or Oric 1 to verify that you're emulating the thing as close as possible?
I don't say you should but IMHO it'll help you a lot.

How about the Sedoric bug? any more advance in here?

Thanks for Oriculator.
regards
kml
Xeron wrote:The blink attribute is handled by the ULA, and even though I don't have a real Oric to test, i'm 99.99999% sure it'll be faster in 60Hz mode.

The BASIC cursor is VIA timed, and should therefore remain constant.

BTW, Oriculator's timings have always been scanline based, and so the video to cpu clock timings should actually be very good in Oriculator (better than Euphoric, if the concerns raised in that google groups link are still true), and where they're out its just a case of changing a value in the source.
/kml
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Xeron
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Re: Oric real HW

Post by Xeron »

kamelito wrote:Don't you have any real Atmos or Oric 1 to verify that you're emulating the thing as close as possible?
Nope. I wrote it entirely from information found online.
I don't say you should but IMHO it'll help you a lot.
Of course it would, but I don't have one. I was kind of hoping for some help once it got this far, but it seems I'm still on my own ;-) I'm not complaining, i enjoy working on Oriculator.
How about the Sedoric bug? any more advance in here?
No. I'm pretty convinced its not a bug in the CPU. Its more likely something really subtle and timing/interrupt related in the disk emulation, which is probably going to be a real pig for me to find because I know nothing about disk drives or disk drive controllers.
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Post by Dbug »

I actually asked André Chéramy if he had any idea about the Sedoric issue, he told me that probably the best thing would be to contact Fabrice Frances (Euphoric author), but I have to admit that I feel uneasy about asking him myself to help finishing another emulator.

I tried to help as much as I can, but I reach the point where I've not idea about what's wrong, Xeron already knows more about the Oric hardware than me...
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Fabrice

Post by kamelito »

I've not heard about Fabrice since ages. Don't really understand why he left the Oric community. I remember him being bothered because nobody was doing much for it (the Oric) back then.
He's a nice guy I met him once in Toulouse since its where my family live, he was into electronics stuffs don't remember really about what...
Too bad he's away since he's a Master of the Oric and now that many projects are ongoing its input would be very valuable.
Fabrice if you reading this come back.

Regards,
kml

Dbug wrote:I actually asked André Chéramy if he had any idea about the Sedoric issue, he told me that probably the best thing would be to contact Fabrice Frances (Euphoric author), but I have to admit that I feel uneasy about asking him myself to help finishing another emulator.

I tried to help as much as I can, but I reach the point where I've not idea about what's wrong, Xeron already knows more about the Oric hardware than me...
/kml
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Re: Oric real HW

Post by kamelito »

hi

what kind of help are you looking after?
A bounty so you can buy a real Oric can be a good start any donators interested?
Count me in!
Anything else?
Kml
Xeron wrote:
kamelito wrote:Don't you have any real Atmos or Oric 1 to verify that you're emulating the thing as close as possible?
Nope. I wrote it entirely from information found online.
I don't say you should but IMHO it'll help you a lot.
Of course it would, but I don't have one. I was kind of hoping for some help once it got this far, but it seems I'm still on my own ;-) I'm not complaining, i enjoy working on Oriculator.
How about the Sedoric bug? any more advance in here?
No. I'm pretty convinced its not a bug in the CPU. Its more likely something really subtle and timing/interrupt related in the disk emulation, which is probably going to be a real pig for me to find because I know nothing about disk drives or disk drive controllers.
/kml
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Xeron
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Post by Xeron »

No, I actually don't think a real oric will be all that useful.

I meant help getting disk support working, for example. But I am making progress anyway.
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