Commodore 1541-II - Changing the Device Number

APPENDIX A: CHANGING THE DEVICE NUMBER
SOFTWARE METHOD
One way to temporarily change the device number of a disk drive is via a program.
When power is first turned on, the drive reads an I/O location whose value is controlled
by a jumper on its circuit board, and writes the device number it reads there into memory
locations 119 and 120. Any time thereafter, you may write over that device number with
a new one, which will be effective until it is changed again, or the 1541 is reset.
FORMAT FOR TEMPORARILY CHANGING THE DISK DEVICE NUMBER:
PRINT#15,''M-W"CHR$(119)CHR$(0)CHR$(2)CHR$
(device # + 32)CHR$(device # + 64)
EXAMPLE:
Here is a program that sets any device number from 8-11:
10 INPUT'NEW DEVICE NUMBER';DV
20 IF DV<8 OR DV>11 THEN 10
30 OPEN 15,8,15
40 PRINT#15,"M-W"CHR$(119)CHR$(0)CHR$(2)CHR$(DV + 32)CHR$(DV + 64)
50 CLOSE 15
Note: If you will be using two disk drives, and want to temporarily change the
device number of one, you will need to run the above program with the disk drive
whose device number is not to be changed turned off. After the program has been
run, you may turn that drive back on. If you need to connect more than two drives
at once, you will need to use the hardware method of changing device numbers,
although you may be able to get by in an emergency by unplugging the serial bus
cable from drives whose device number has already been set while changing others.
This is not recommended, however, as there is always danger of damaging
electronic devices when plugging in cables with the power on.
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