MsxKun, good, so it’s confirmed then that there are two revisions of the HB-20P 
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Out of curiosity, you don’t see a distinguishing indication in the model, type or serial number do you?
Thank you for Uridium conversion! The more I play, the more I like it! There are couple of things missing though, kamikaze satellite, which makes game a bit harder, is missing and end of stage mini game is missing too.
John, I must say I like you SCC+PSG arrangement more than PSG only. Though, I have played much with music turned almost off, as it feels more familiar for me. It was a great thing that music volume could be tuned to desired level! But for some reason, one can´t completely mute it off. 
I liked the way SCC starts to lose "pure sound" when volume is set to 13 - 15, SCC sound starts to get "inaccurate", the way John described Commodore 64´s SID sound. I like that! I do really hope, you could use that kind of sound in your arrangements some day, John! Yes, I know you are a pure sound guy, but I can wish at least. 
Please ignore my previous post, it's now been 'moved' to a separate thread. Sorry! 
Thank you for Uridium conversion! The more I play, the more I like it! There are couple of things missing though, kamikaze satellite, which makes game a bit harder, is missing and end of stage mini game is missing too.
John, I must say I like you SCC+PSG arrangement more than PSG only. Though, I have played much with music turned almost off, as it feels more familiar for me. It was a great thing that music volume could be tuned to desired level! But for some reason, one can´t completely mute it off.
Satellite and bonus game do not fit in rom, sorry.
Volume controls were there only to fix scc vs psg balance, there is no way to turn off music.