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PR77 · 20 March 2019, 21:36

R3/5 have A17 pinned differently so that explains the pull ups (or pull downs- depending on where in the memory space you are addressing. R6 and up have the ROM socket routed for larger ROMs sizes already.

I would also check RP105 as this is pulling the higher address lines high. But to be honest, if there is an issue with the address lines I would expect the Amiga to simply not work.

Perhaps check if AGNUS is correctly socketed and if RP201, 202 and 203 are OK. Might be helpful to put some pressure on the RPs during measurement as they are thin film ceramic, a potential crack may not be obvious.

20 March 2019, 21:36	#6
PR77 Registered User Join Date: Oct 2017 Location: Germany Posts: 193	R3/5 have A17 pinned differently so that explains the pull ups (or pull downs- depending on where in the memory space you are addressing. R6 and up have the ROM socket routed for larger ROMs sizes already. I would also check RP105 as this is pulling the higher address lines high. But to be honest, if there is an issue with the address lines I would expect the Amiga to simply not work. Perhaps check if AGNUS is correctly socketed and if RP201, 202 and 203 are OK. Might be helpful to put some pressure on the RPs during measurement as they are thin film ceramic, a potential crack may not be obvious.