June 21, 2017 11:01 AM, groepaz@gmx.net wrote: > On Wednesday 21 June 2017, 16:40:03 silverdr@wfmh.org.pl wrote: > >> According to the famous document by Chris Bauer, there are three timing >> variants of the VIC-II. While PAL is always 63 cycles per line, with NTSC >> there can be either 64 or 65 cycles per line and I am in fact able to >> reproduce the difference with -model ntsc and -model oldntsc in the current >> VICE. >> >> The question (before I spend weekend on trial'n error counting cycles and >> possibly reinventing the hammer ;-) is: do we have ane established, >> reliable software method for detecting which NTSC VIC-II is installed in >> the machine? I guess it must have been done multiple times by now and used >> in some NTSC games/demos.. > > most demos or games probably dont care about detecting the difference - as the > 64 cycle VIC is extremely rare. > > however, iirc on codebase there are some detection routines. basically just > count the cycles for a line (or a frame) using a CIA timer. > I wouldn't call them "extremely rare". They were in all the early C64's extending way beyond the silver badge era. Going by my serial database, I would say they were in the first ~300,000 C64's since they were found in all 326298 boards (all the S-series machines which stop before 00100000, and at least the first 2.5 hundred thousand P-series, which start at 00100000). I don't have enough samples to know how many of the Canadian machines there really were, but they were in those also. Now, are they being used as "daily drivers" still- I doubt it. The video quality is greatly enhanced, even on the old board, but upgrading to a newer revision. The old 6567R56A chips have very grainy, low-contrast video. -- Pete Rittwage C64 Preservation Project Message was sent through the cbm-hackers mailing listReceived on 2017-06-22 03:00:02
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