On 2017-02-19 23:07, silverdr@wfmh.org.pl wrote: > >> On 2017-02-19, at 22:45, HÁRSFALVI Levente <publicmailbox@harsfalvi.net> wrote: >> >>>> There is clearly a visible difference between an R3 and an R5 on a 250466 board. (I've been using an R3 after having killed the original R5 of the machine / before I could obtain another one.) >>> >>> Could you elaborate/describe the difference? It's been some time since I tried those (and it was not in the '466 either) but I didn't notice anything striking. The R1 with its luma levels makes a noticeable difference but the later ones? >> >> Less contrast, more blurry / noisy / subjectively darker startup screen. Nothing as obvious as the 6569R1 with its fewer luminance levels, but still something clearly noticeable. > > Uhm in that case.. shall have to check again and try to do some semi-scientific measurements. I should add that I always use CRT displays to play around with vintage gear (if I just have a chance). I observed the above on a usual CRT display, at the time probably a tv set from the early 90s. Another addendum: Marko once measured the luma levels of different VIC-II chips in the same C64 motherboard, http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/656x-luminances.txt . I don't know how well the data practically holds, since the measurements have been done without using a standard 75 ohm load; yet, one thing seems to be sure: there are slight differences between different VIC-II chip revisions in the luma levels they produce. Maybe part of what I've seen has been a result of that. I can't speak of the other symptoms, I didn't make measurements myself. > >> (Worst of all, with the R3 installed the machine started to exhibit VSP crash symptoms, which it never did previously. > > But that - again - doesn't have much to do with the parameters of the picture it generates. Yes. Levente Message was sent through the cbm-hackers mailing listReceived on 2017-02-19 23:01:13
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