This is a small MivaVM disassembler I coded when bored. (Yes, it's completely unofficial. I have no affiliation with Miva, Inc. I'm still unsure if Miva themselves have any kind of disassembler that they use internally, asides from leftover code in MivaVM and mvasm that seems to just dump opcodes anyway.)
more here............https://github.com/Wack0/mvdasm
more here............https://github.com/Wack0/mvdasm