How to change the device number of the CBM-dual-drives
All CBM disc-drives have the standard device number 8. To change the device number by software, there are several programs available, for example on the Test-/Demodisc from CBM. The disadvantage of these programs is that after a reset or turning the drive off and on the device number is restored to 8. To change the device number of the dual drives CBM 3040, 4040, 8050 or 8250 by hardware, you need to do the following things:
First, you must open the drive by removing the screws. Then you have to search for the IC named "UE1" on the digital-board. To the left of the IC there are three round blocks printed on the digital-board. Pin 22 of the IC is connected with the uppermost round block, Pin 23 with the block in the middle and Pin 24 with the undermost block. To change the device number, you must remove the IC from the digital-board and bend the Pins you need for the new device number (see the table below). To "bend" means in this case that the Pin must be out of the IC-socket when you put the IC in the socket again. Now your drive has a new device number.
| DEVICE NUMBER | PIN 22 | PIN 23 | PIN 24 |
| 8 | 0 | 0 | 0 |
| 9 | 0 | 0 | 1 |
| 10 | 0 | 1 | 0 |
| 11 | 0 | 1 | 1 |
| 12 | 1 | 0 | 0 |
| 13 | 1 | 0 | 1 |
| 14 | 1 | 1 | 0 |
| 15 | 1 | 1 | 1 |
In the table "0" means that the Pin need not to be bended and "1" that the Pin MUST be bended.