MEGA65 / mega65-core

MEGA65 FPGA core
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r5/r6 expansion port problems - a lot of cartridges don't work #778

Open lydon42 opened 5 months ago

lydon42 commented 5 months ago

A lot of standard stuff does not work anymore in the r6/r5 mega65 core, which did run before and which do work in the r5/r6 c64 core.

So we obviously need some more fixes for the port in the new core.

gardners commented 5 months ago

Possibly relevant: michael says: I can have a look tomorrow. One thing to remember is to pull EXP_SLOT_EN (FPGA pin T21) high. Not sure if that is already done.

paich64 commented 5 months ago

Here are my tests with the last Mega65 core (Megaflash release number 65)

dansanderson commented 5 months ago

Modern carts with issues on R5 + C64 core:

Vintage carts with issues on R5 + C64 core:


Modern carts working with R5 + C64 core:

Vintage carts working fine with R5 + C64 core:

I spot checked the working ones with the M65 core in GO64 mode. The ones I checked load up to their title screens just fine, but I can't tell if misbehavior is due to expected GO64 mode incompatibility.

gardners commented 5 months ago

ok, so I have a Sam's Journey cart here, which is listed as not working on R5, so that's probably a good one for me to focus on initially.

paich64 commented 5 months ago

As opposed to issue 781 where there is a work around which is about power cycling with NOSCROLL and select the C64 core manually, here there's obviously no workaround :

With latest MegaFlash in slot 0 and core 0.96 in slot 1, no C64 core installed, power cycling without NOSCROLL won't start Sam's Journey (black screen) and power cycling with NOSCROLL and selecting slot 1 (core 0.96) will result in the exact same black screen.

Doing the exact same test with R3A and Sam's Journey (using the exact same cores in slot 0 and slot 1) results in Sam's Journey starting, whatever the method used to start core 0.96 is.

gardners commented 5 months ago

Handling #778 and #781 together on 781-c64-carts branch

gardners commented 5 months ago

The above commit almost certainly fixes this issue.

paich64 commented 5 months ago

I confirm that on R5, with no C64 core installed, pushing the fixed bitscreen now results in :

dansanderson commented 5 months ago

My ProtoVision cart that was having the issue appears to be a gmod2 cart. I wonder if the issue is general to gmod2 carts. http://wiki.icomp.de/wiki/GMod2