HP 3326A Operating And Reference Manual page 81

TalklL~sten Addresses
The address of a device is usually preset at the factory and is resettable during system
configuration. In the binary representation of the address, the device address is the
decimal equivalent of the five least significant bits of the address. (On HP-IB devices
with selector switches, these are the five address switches.) The address can be from
0 to 30 inclusive. The sixth and seventh bits determine if the address is a talk or listen
address respectively. High level HP-IB controllers typically configure these two bits au-
tomatically. Figure 2-4 lists the HP-IB addresses if a controller requires the talk and
listen addresses.