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Device Address Switch

Project: Switch to change the drive's hardware address
Target : 1541 (not 1541-II), 1570
Time   : 20 min.
Cost   : <2 US$
Use    : Possibility to have more than one device attached to
         the serial bus without having to switch device addresses
         manually on each power-up.


Connect switch(es) to the 1541's internal device address jumpers.


The 1541's circuit board has two jumpers which tell the drives's CPU on which address it should react. Open the jumpers using a sharp knife and solder one or two switches to them to choose between two or four different addresses.

If you don't install the switch(es), you have to switch off all drives on the serial bus except for one, then type the following:


where 'no' is the device number you want the floppy to have. Then switch on the next floppy drive and set its device number the same way you did with the first drive. Proceed until all drives are switched on. Note that this procedure must be repeated every time you switch on a drive!



  1. Disconnect drive, then open case.
  2. Search for the two jumpers near capacitor C46, possibly located between transistors Q4 and Q5.

    [Possible location #1] [Possible location #2]

    On a few boards the CIA is on position UAB1, in this case the two jumpers are directly in front of pins 15 and 16.

  3. Open the jumper(s) using a sharp knife or similar.
  4. Solder the first cable to a switch, then solder one lead to one side of jumper 1 and one lead to the other side. If you want to use two switches, do the same with the second switch/cable/jumper.
  5. Connect power plug.
  6. Switch your C-64 and your 1541 on. After the startup screen appeared, type LOAD"$",x and hit [RETURN], where x is one of 8,9,10 or 11. The 1541 should react on exactly ONE device address, which corresponds to the following jumper settings:
              J1      J2   | Addr
            closed  closed |  8
             open   closed |  9
            closed   open  | 10
             open    open  | 11
  7. If everything works fine, attach the switch(es) to the case and close it again.

Possible failures

Updated: April 26th, 1998
Created: February 4th, 1997
Status : Verified on September 30th, 1997

Site copyright © 1997 by Marc-Jano Knopp
This document is part of MJK's Commodore 64 & LCD Page
Brought back to life by Peter Schepers, Dec 10, 2005 because I really liked this site!