2600: Activision Decathlon can randomly fail to launch

[Thelypody]

When switching 2600 games between each other, Activision Decathlon (CRC-32: 3FEB39B1) sometimes fails to autodetect its FE mapper. This produces a completely unusable video signal on analog display which can be remedied only by resetting MiSTer. Decathlon seems to always load properly when it is the first 2600 game launched by the core and only starts to fail after loading another 2600 game before Decathlon.

[Kitrinx]

I can't seem to reproduce this. I've been going back and forth between various FE roms and random other roms and they always seem to load correctly.

[Thelypody]

Strange, for me Activision Decathlon still crashes randomly, even with the fresh core release. I've tested it some more and came to some conclusions: 1) Robot Tank and Thwocker never crash for me, leading to a conclusion that the issue is relevant only to Activision Decathlon. 2) Activision Decathlon can crash even if it is the very first game launched by the core. 3) Activision Decathlon can crash when loading it after Activision Decathlon itself. 4) Manually setting the Bank Switching type to FE before loading the game can still crash Decathlon on boot!

I assume that at this point the issue is not related to mapper detection at all and must have something to do with inner workings of Activision Decathlon exclusively. I'm using a rom from Atarimania romset V17 marked as "Activision Decathlon, The (1983) (Activision, David Crane) (AG-930-04, AZ-030) [fixed] ~.bin" with a CRC-32 checksum of 3FEB39B1.

[Kitrinx]

I am able to reproduce this now with that CRC of the rom if I load the same game twice in a row. I will investigate.

[trebor68]

This post: https://forums.atariage.com/topic/293982-mechanics-of-fe-bankswitching/?do=findComment&comment=4319174

From this thread: https://forums.atariage.com/topic/293982-mechanics-of-fe-bankswitching

The above may be of value here.

As a side note, the difference between the other good dump: "Activision Decathlon, The (1983) (Activision, David Crane) (AG-930-04, AZ-030) ~.bin [CRC 91B8F1B2], and the one in question here: "Activision Decathlon, The (1983) (Activision, David Crane) (AG-930-04, AZ-030) [fixed] ~.bin [CRC 3FEB39B1], is the 'fixed' version is a later release that fixed an issue with the Pole Vault event. It is mentioned here: https://forums.atariage.com/topic/103737-2600-rom-comparisions-and-dumps/?do=findComment&comment=1437104

The difference with the Pole Vault event is mentioned here: https://forums.atariage.com/topic/42730-activisions-decathlon-without-pole-vault-glitch/?do=findComment&comment=514415