Fully tested original Apple logic board for a Macintosh SE originally fitted with an 800K floppy disk drive but which has subsequently been upgraded to a 1.4MB drive by replacing two ROM chips. For an SE that was originally fitted with a 1.4MB floppy drive, you should use logic board part number 661-0536.
Logic boards from machines that were originally fitted with 1.4MB floppy disk drives can be easily identified by the fact that their backup battery is removable and in a plastic holder. The battery on versions originally fitted with 800K floppy drives are soldered onto the logic board.
NOTE: To determine if a board has been upgraded. check the Apple part numbers on the ROM and floppy controller chips:
Original
342-0352-A - HI ROM
342-0353-A - LO ROM
344-0043-A - IWM
Upgraded to 1.4MB FD
342-0701 - HI ROM
342-0702 - LO ROM
344-0062-01 - SWM