REU implementation not 100%

[p-a]

The demo Treu Love has visual artifacts in some parts where sprites should show in the side border when running it on the Ultimate. A real REU does not show these artifacts.

http://csdb.dk/getinternalfile.php/144854/TreuLove_ForReal1750Reu.d64

VICE had similar problems and was fixed in revision r31436:
svn log -v -r r31436 https://svn.code.sf.net/p/vice-emu/code/trunk/vice

This comment in VICE gives some clues:

/* The REU can use an additional cycle at the point where the dma of sprite 0 is turned on */
/* this is because of late setting of BA due to internal delays */
/* The CPU can't use this cycle as it checks the state later */