Ah, that brings back decade-old memories. Dreamcast was my last really used gaming console.
I also made a VMU emulator, but never quite figured out how to run the BIOS - there were two opcodes missing from the instruction set that the real BIOS needed, and i had no clue what they were.
The DirectVMS guy, the one who wrote the first (or so) VMU emulator, did figure these opcodes out, but he kept the info to himself with a smug smile.
Anyway, i just checked, and my emulator still works and did compile correctly into JS, so if you want to look what VMU looks like, here is a tetris in it:
I'm the author of ElysianVMU, and I actually have yet to emulate the BIOS for that exact reason... Still working on it... But that's really badass that you have your emulator running in the browser, man. Epic.
Well, i found people to be reluctant to download programs these days, so it's necessary to put them into the browser to be able to show them off efficiently.
As far as i can remember, i figured from the nearby code that the opcodes are read from flash (0x50) and write to flash (0x51), and they read to or store from REG_ACC to the flash at address of word at register 0x105:0x104. But there seems to be something more to it, since that's not enough to boot the thing.
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[ 3.4 ms ] story [ 28.1 ms ] threadI also made a VMU emulator, but never quite figured out how to run the BIOS - there were two opcodes missing from the instruction set that the real BIOS needed, and i had no clue what they were.
The DirectVMS guy, the one who wrote the first (or so) VMU emulator, did figure these opcodes out, but he kept the info to himself with a smug smile.
Anyway, i just checked, and my emulator still works and did compile correctly into JS, so if you want to look what VMU looks like, here is a tetris in it:
http://orbides.org/apps/evmu.html
A,B Start and Mode use the A,B,S,M keys, arrows are IKJL.
Timings might be off a bit, this thing is quite old.
I wonder how much knowledge has been lost from the emulation scene as a whole because of that kind of attitude.
At least the current batch of emulators (Xenia, Citra, RPCS3 etc) seem to be open source.
Me, i was never known in the scene.
As far as i can remember, i figured from the nearby code that the opcodes are read from flash (0x50) and write to flash (0x51), and they read to or store from REG_ACC to the flash at address of word at register 0x105:0x104. But there seems to be something more to it, since that's not enough to boot the thing.
In any case, good luck!