The only difference between a Dai-Ou-Jou and Dai-Ou-Jou Black Label lies in the program EPROM. To avoid people converting a normal Dai-Ou-Jou to a Black Label CAVE added some protection.

The setup parameters on the PGM PCB are stored in battery backed RAM. On the Black Label this RAM contains two magic values which the program verifies on startup. If these values are not present you will get "ROM ERROR" at powerup.

The RAM is powered by a 3V6 NiMh Varta 3/V80H rechargeable battery. This battery will slowly lose it's charge unless the board is regularly powered up. When the battery is discharged the RAM content
is lost and the board will start up with "ROM ERROR"

It is possible to change the battery to prolong the life of the PCB but this must be done while the PCB is powered. When handling the PCB it is extremely important to avoid manipulating the brown SW1 switch. When you toggle this switch the Vcc pin of the RAM chip is pulled to ground clearing the RAM instantly and leaving you with a dead board.

With kind assistance from the "encryption faery" and Charles MacDonald, I have devised a method of resurrecting dead Dai-Ou-Jou Black Label PCB's. Please contact me on the shmups messageboard if you need to resurrect a dead Dai-Ou-Jou Black Label PCB.