rEVERSE ENGINEERED SCHEMATIC DIAGRAM OF THE 1551 MAIN BOARD.
dRAWN BY jERZY sOBOLA, jUNE 20, 1999. dOWNLOADED FROM HTTP://WWW.REPUBLIKA.PL/JSOBOLA/SCHEMATY.HTM. tHIS DIAGRAM
SHOWS A 6523 AT LOCATION u3, WHILE THE cOMMODORE SCHEMATIC DIAGRAM
SHOWS A 6525a tpi THERE.