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ACB-232XB User's Manual
jumpers) and the drive termination. The drive selection switches and cabling select the
address (drive address 1-4 ) to which the drive will respond. This is accomplished either by
setting both drives to be the second lowest address and using a twisted 34-pin cable, or by
setting the drive address to the lowest two addresses and using a flat cable.
A. Twisted 34-Pin Cable
The typical AT 34-pin cable has three connectors. Between the first (middle) drive
connector (for drive D) and the second drive connector (for drive C) wires 25 through 29
are twisted, thus inverting the drive selection wires. This type of twisted cable allows both
drives to have their drive selection switches (or jumpers) to be the same. Both drives must
be set to the SECOND lowest drive address. The controller will see the two drives to be
drive 1 and drive 2, depending on the position of the connector that is used.
B. Flat 34-Pin Cable
In some cases a 34-pin flat (non-twisted) cable is used. This cable does not invert the
drive selection wires but relies on the drive addresses to be unique for each drive. Now
drive 1 must have its drive selection switches (or jumpers) set to be the lowest drive
address (typically 1). Drive 2 must have its selection switches (or jumpers) set to be the
second lowest drive address (typically 2). The controller will see the two drives to be drive
1 and drive 2, independent of the position on the connector that is used.
C. Terminator
Before the drives can be cabled to the controller, the drive cable terminator must be
properly set.
The terminator is used to reduce signal "ringing" in the cables. The
terminator, as its name implies, must be at the end of each cable in order to have the
controller and drive communicate properly. The controller has a permanent terminator built
into it. The disk drives, since they can be connected in a daisy-chain configuration, have a
removable terminator. This is usually a 16-pin DIP resistor package located on the drive
PCB. The last physical drive in the chain must always have its terminator installed. When
two drives are connected to the same controller, only the last one in the daisy chain is
terminated. The other drive must have the terminator resistor removed.
Now select the proper drive addresses and remove or install the required terminators for
your system.
Step 3 (ACB-2322B Only) Floppy Disk Cabling, Drive Selection and Termination
The typical AT 34-pin floppy disk cable has three connectors. Between the first (middle)
drive connector (for drive B) and the second drive connector (for drive A) wires 10 through
16 are twisted, thus inverting the drive selection wires. This type of twisted cable allows
both drives to have their drive selection switches (or jumpers) to be the same. Both drives
must be set to the SECOND lowest drive address (typically 1 since floppy drives are
addressed as 0-3). The controller will see the two drives to be drive 0 and drive 1,
depending on the position of the connector that is used.
Termination of the floppy disk drives is the same as the hard disk drives in step 2.
(http://www.franken-online.de/ymmv)
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