On Mon, Sep 6, 2021 at 9:44 PM Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de> wrote: > > > None that I know of. I have a 1541-II clone, the Oceanic OC-168 and the > CPU used is an UM6502 (and two UM6522 for the VIAs). The drive runs with > an original ROM from a 1541-II and behaves normally. > > If it's a load or level issue, you should be able to see differences on > a scope. If the game never crashes, then you should take a closer look > at the circuit between CPU and the beam control. Maybe some IC there is > a bit more sensitive than it should be. Like 74HCxxx instead of 74HCTxxx. > these games are from 1979, the actual boards I have are populated with 79xx and 80xx date codes. Most of the logic is either 74LS or 74 family. The oldest board has a few 93 family chips. I tend to believe it's not a level issue on either the databus or the address bus since the game never crashes. It could be an issue with the phi2 output, but it seems odd that the newer UM6502 have weaker drivers than any random 198x 6502 I could find at home. Yeah... I'll try to look at phi2 and maybe R/W, I can't think of anything else that could cause these strange glitches. Best regards FrankReceived on 2021-09-07 00:00:03
Archive generated by hypermail 2.3.0.