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TWW
Registered: Jul 2009
Posts: 555 |
NTSC Raster Positions
Good afternoon gents.
Is Rasterline #$00 to #$13 located in the lower border on NTSC machines when bit 7 of $d011 is cleared?
Tried to do a vsync (bit $d011 + bpl/bmi) and turned to debug borders and had to wait for rasterline #$14 before it was in the top border.
On PAL it works as expected though. |
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chatGPZ
Registered: Dec 2001
Posts: 11510 |
You have basically provided the answer in your question - just try it in VICE, it does the right thing in that regard for sure :) |
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Monte Carlos
Registered: Jun 2004
Posts: 370 |
Guess, you had the BPL/BMI in the wrong order. |
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chatGPZ
Registered: Dec 2001
Posts: 11510 |
Quote:just try it in VICE |
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Krill
Registered: Apr 2002
Posts: 3083 |
What GPZ said. The NTSC peculiarity to have the top visible line not be 0 while line 0 is visible somewhere in the lower border has long been implemented in VICE, and properly.
This kind of basic stuff is never an emulation error, just like uninitialised memory in user programs is the culprit in 99% of reported problems. =) |
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TWW
Registered: Jul 2009
Posts: 555 |
@ chatGPZ: Yepp, was trying it on Vice (Hence the debug borders), but never knew about this NTSC Bahaviour so figgure'd I'd ask.
@ Monte Carlos: Nah, bit 7 was cleared, but also tried the other way just to see what happened, ond it only moved the line to 256 instead of 262/263
@Krill: Yeah, I figgured as much, but it has been stated that one should never trust an emulator :D
Either way, thanks for confirming. At least line #$0032 is still in the same place :) |
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tlr
Registered: Sep 2003
Posts: 1807 |
Quoting TWW@ chatGPZ: Yepp, was trying it on Vice (Hence the debug borders), but never knew about this NTSC Bahaviour so figgure'd I'd ask.
Quoting TWW@Krill: Yeah, I figgured as much, but it has been stated that one should never trust an emulator :D
Agreed, you shouldn't trust it blindly. Always good to ask. |
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chatGPZ
Registered: Dec 2001
Posts: 11510 |
Not trust blindly indeed. But for basic stuff like this there is a 99,999% chance VICE is doing the right thing :) |
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Fungus
Registered: Sep 2002
Posts: 746 |
I recall bugging groepaz ages ago to fix the vertical blanking area to be on the correct lines. So they should be correct at least for NTSC 64, I never had an old (5 lum) VIC to test so if it's correct or not I have no idea. Same for R56A VIC, could be correct might not be, but those are rare and who cares. |
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chatGPZ
Registered: Dec 2001
Posts: 11510 |
In the meantime i ported a bunch of the test programs to NTSC too (regular 65 cycle) and verified they work on the real thing as well as in VICE - so it should be quite ok :) |
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Fungus
Registered: Sep 2002
Posts: 746 |
Right on.
Did you ever got those other VIC variants yourself? Or maybe C0? |
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