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MJoergen / C64MEGA65

Commodore 64 core for the MEGA65 based on the MiSTer FPGA C64 core
GNU General Public License v3.0
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Demo "Old Men in Used Cars" by "Fossil" stops working with V5.1RC2 #135

Open paich64 opened 2 months ago

paich64 commented 2 months ago

Demo "Old Men in Used Cars" by "Fossil" stops working with V5.1RC2 :

When inserting disk n°2, the first picture gets loaded and the music plays, but the visual effects just stop.

Since there is an already exisiting issue with V5.1RC2 issue 133 I have tried the demo with the V5.1A16 core which fixes issue 133, and the demo runs perfectly as with V5.0.

summary :

"Old Men in Used Cars" by "Fossil" works fine with V5.0 "Old Men in Used Cars" by "Fossil" stops working with V5.1RC2 "Old Men in Used Cars" by "Fossil" works fine with V5.1A16

sy2002 commented 1 month ago

My hypothesis is, that this regression was introduced by the GEOS RTC feature that has been introduced in V5.1. A strong data point that backs this hypothesis is, that V5.1A16 resolves the issue: Alpha 16 was a never-released Alpha version that did nothing else than deactivating the RTC that uses the C64's tape port. So it looks like this demo does not like if the tape port is active while it runs, just like TRAP16 in the emulator test suite: https://github.com/MJoergen/C64MEGA65/issues/133

The decision is to live with this regression in V5.1 as the benefit of having a RTC for GEOS is larger than this singular demo. In future, we will have advanced compatibility settings and will be able to switch the RTC on/off. Today the default is ON and in future it might be OFF just to be more compatible.