CHANGING A DRIVE FROM DEVICE 8 TO DEVICE 9, 10, or 11

             Latest additions & corrections: 9-11-2013

     The internal 1571 in the metal case USA version C128DCR has no
external switches for drive select. It is factory set for device #8.
There are drive select "jumpers" inside the computer however, on the
motherboard near the drive. They are the two tiny silver half-circles
with a bar between them. Cutting the bar opens the jumper. If you look at
the PC board just under the left side of the drive, you will see them. It
is not necessary to remove the drive unless you plan to solder in there.
The jumpers are located near ICs U106 (a 6522), U114 and U112. DS (drive
select) jumper #1 is nearest to U112, towards the front of the computer.
     Electrically, the jumpers connect two pins of IC U106 VIA chip
(65C22 or 6522 in some models) to chassis ground. Jumper 1 grounds pin 15
and jumper 2 grounds pin 16. That information is helpful just in case the
foil pad(s) jumpers on the PC board are accidently damaged when you are
installing a drive select switch. If the pads lift off the board, you can
still make connections directly to the IC pins for your switch.
     The 1570 drive is not as common but is similar to the 1571 in that it 
uses the same board, will do burst-mode data transfers with the C128, and 
will do MFM as well as GCR disk encoding like the 1571. Since it has only 
one head, it uses SSDD disks like a 1541. It has no drive select switches
but instead has internal jumpers. They are connected to VIA U9 pins 15 and
16. I have never seen a 1570, so my information about it is minimal.