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.

Summary

Details

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:

  OPEN15,8,15
  PRINT#15,"M-W";CHR$(119)+CHR$(0)+CHR$(2)+CHR$(no+32)+CHR$(no+64)
  CLOSE15

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!

Ingredients

• 1 or 2 single-pole snap switch(es)
• 1 or 2 ~30 cm two-core cable(s)

Instructions

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

   

   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

• You did not attach the switch(es) to the right jumpers.

Site copyright © 1997 by Marc-Jano Knopp