Posted By
crock
on 2011-12-02
08:06:41
 |  Can someone run this on genuine NTSC hardware?
I'm doing some work on the free running timers and raster interrupts. I would really appreciate it if someone could run this small program on real NTSC hardware an post me the results.
When it runs it will output 8 hex bytes to the screen. On typical PAL hardware, it would be:
INTERRUPTS 53 0B 0A 26
CLOCK DOUBLE 26 05 04 11
I need to know if there's any differences on NTSC iron.
Cheers, Rob
http://inchocks.co.uk/c64/264/timer.prg
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Posted By
crock
on 2011-12-16
15:03:47
| Re: Can someone run this on genuine NTSC hardware?
Pretty please? It would really help me out. 
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Posted By
Csabo
on 2011-12-16
16:49:23
| Re: Can someone run this on genuine NTSC hardware?
When I think "who has NTSC hardware" I can only think of JamesC and myself... For me, the will is there, I would like to help, but the time and opportunity isn't... We just put up our Christmas tree in our living room, there's even less space now, and I don't even know where my boxes with the Plussy stuff are. It's sad, I know.
James hasn't been around for a long while now, I don't know what he's up to. I do recall him posting a picture of his gear (meaning the Plussy was actually "out", not in some box). You could try emailing him.
Oh, shoot, I just remembered, MikeZ is also in the States (haven't heard of him from a long while either). You could definitely try emailing him.
Anyone else?
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Posted By
RobertB
on 2011-12-17
05:30:20
| Re: Can someone run this on genuine NTSC hardware?
Now that I am on vacation for the next 3 weeks, I will see if I can test it.
Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
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Posted By
crock
on 2011-12-17
06:58:30
| Re: Can someone run this on genuine NTSC hardware?
Thanks Robert - appreciated.
@Csabo "I don't even know where my boxes with the Plussy stuff are. It's sad, I know." 
WTX - Have you retired??
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Posted By
Csabo
on 2011-12-17
16:41:59
| Re: Can someone run this on genuine NTSC hardware?
No, but my Plussies have. I haven't had them out in... well, not sure, but many years. It's all PCs and emulators and sadness for me. Yes, I know that doesn't befit a self-described Plus/4 fanatic - I'm hanging my head in shame.
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Posted By
TLC
on 2011-12-18
04:53:17
| Re: Can someone run this on genuine NTSC hardware?
Crock, I also do have an NTSC machine, unfortunately not at hand. (I keep most of my rarely used stuff in my parents house ie. where I grew up). And even if I had one here, time has been a limiting factor for the last couple of weeks. I do have a "non-genuine" piece here ie. a PAL C16 that I had modified for PAL and NTSC compatibility (osc and ROM). If that fits, I can possibly give that one a try.
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Posted By
crock
on 2011-12-18
06:56:46
| Re: Can someone run this on genuine NTSC hardware?
@TLC - That would be great. If it's an ntsc kernal and oscillator - that would be v useful (not to mention a damn good idea)
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Posted By
TLC
on 2011-12-19
11:29:40
| Re: Can someone run this on genuine NTSC hardware?
Did a couple of minutes ago.
Results:
84 0b 0a 2f
3b 05 04 15
HTH
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Posted By
siz
on 2011-12-20
02:03:46
| Re: Can someone run this on genuine NTSC hardware?
Interesting. YaPE gives different results:
55 0B 0A 2F
26 05 04 14
:O
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Posted By
crock
on 2011-12-20
05:36:07
| Re: Can someone run this on genuine NTSC hardware?
Wow - those numbers really surprise me.
They represent the number of interrupts that have occurred during the time it takes to execute a simple nested loop, which based on my math, lasts for 525353 cycles. The first line is with TED forced into single clock mode and the second with the screen blanked and thus in 2 x clock.
From left to right, the numbers are the number of interrupts that occurred with:
1) Timer 1 initialized with a reload value of $2000
2) Timer 2 initialized with a value of $0100 (remembering that it reloads with $ffff)
3) Timer 3 initialized with a value of $ff00 (remembering that it reloads with $ffff)
4) Raster interrupts
On an NTSC machine, a slightly different number of raster interrupts makes sense, and timers 2 and 3 are the same, but I cannot explain why timer1 is so radically different, ie. by about 50%!!
My understanding was that the TED timers are decremented at the clock speed so I would have expected the figures to be very similar if not identical between NTSC and PAL.
@TLC - is this machine modded in any way (either ROM or hardware, excluding your oscillator mod), any add on hardware that could be generating additional interrupts?
Any theories appreciated....
Rob
edit : 64tass source - http://inchocks.co.uk/c64/timer.asm
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Posted By
TLC
on 2011-12-20
04:52:04
| Re: Can someone run this on genuine NTSC hardware?
I had saved your routine way before I replied to this topic... (thought I could give it a try as I was to go "home" that weekend anyway... which didn't happen (time constraints again)). Looks like it's an earlier version... at least after having downloaded and compared the currently available one.
Yeah, this latter one seems to match your expectations. It reports a stable 55 0b 0a 2f / 26 05 04 14 just as Yape does (thanks siz! ). (The previous one, as I can see now not only gives different but also a bit... err... dispersed results over different runs).
Nope, otherwise, the machine wasn't modded significantly (a flash rom that replaces ROM chips, plus the oscillator hack; the last two photos of this album show that, http://www.facebook.com/media/set/?set=a.1521078354424.2068921.1458531880&type=1&l=d882edf42b ).
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Posted By
crock
on 2011-12-20
05:34:53
| Re: Can someone run this on genuine NTSC hardware?
Ah, much better. Yes, the first version was a bit flaky, I didn't think it was up there long enough for anyone to download so I didn't mention I'd updated it.
I think I was having a boolean 'moment' and enabled all the timers except the one I wanted...
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