On 14/10/2016 08:27, Gerrit Heitsch wrote: > You cannnot run the refresh cycles only in the upper and lower border, > the screen part takes more than 4ms to display which will take you out > of spec for the DRAM. The badline fetches should be reading the DRAM enough to refresh it (as long as the screen is enabled). When it's disabled then vic2 reverts to the upper/lower border case. So I wonder why they didn't make the upper/lower border+blank screen fetch $3fxx, instead of $3fff & skip the extra refresh cycles. The apple 2 gets away with it (they have a border too and I assume they fetch during the border). It would have caused them a problem on the C128, because in 2mhz mode the vic2 can't do any fetches. I assume it still pauses the cpu to do refresh cycles each line though. But they didn't design vic2 for the c128. Of course they didn't design vic2 for the c64 either Message was sent through the cbm-hackers mailing listReceived on 2016-10-14 10:01:13
Archive generated by hypermail 2.2.0.