Notes:Thunder Force IV

Demo recording?

 * using a code to force the memory value to 0000 at all times appears to cause the demo to act like a regular game but with one life, then the continue screen takes you back into the normal mode with three; turning the code on during the black screen while a level loads kept the PRESS START showing up on screen with the same effect as here
 * there are two places I know at this moment where the value is cleared; if I nop both the jumps over this set out, the game skips to the choose the first four levels screen after the sega screen? nop out only the second one and the demo skips over to this select four levels screen; clearing the first one has the same effect as clearing both -- I wonder...
 * jopyad input to word $FFFFF120

Debug printing?
The address is the first entry in a table jumped by the game at various points (at the start of a level) but IDK how to get word $FFF272 (the index) to be 0 at the right time (that is, without it stalling the game)...

Things I need to look into

 * OST has some more complete arrangements, most notably Stand Up Against Myself (which is very short in the game) - are these hidden in the ROM?
 * There appears to be a second checksum routine that appears to trigger after a set amount of gameplay? not sure