Specifications

Interrupt Controller (V40)
Initialization Words (IIW1, IIW2, IIW3, and IIW4)
The ICU must be initialized before it can be used. Initialization
consists of writing from two to four bytes called interrupt
initialization words.
The sequence in which these words are programmed is outlined in the
flow chart shown in Figure 8-2. IIW1 and IIW2 must be programmed
during any initialization sequence. IIW3 is not supported by the
ZT 8832 and should be initialized to zero. IIW4 may or may not be
programmed as required by the application. The ICU decodes the first
two bits of IIW1 to know whether or not to expect IIW4 and IIW3,
respectively.
IIW1
IIW2
IIW3
IIW4
IIW4IIW3=0
IIW1 Bit0=1
IIW1 Bit1=0
IIW1 Bit0=0
IIW1 Bit1=0
IIW1 Bit0=1
IIW1 Bit1=1
Base Address +0
Base Address +1
Base Address +1
Base Address +1
Base Address +1
Base Address +1
Initialization
Complete
IIW1 Bit0=0
IIW1 Bit1=1
Figure 8–2. Interrupt Initialization Programming.
8-8