Refining the CCU
Last Edit November 2, 1996; May 1, 1999; July 7, 2001
Am2914
The Am2914 (see Figure 4-29) incorporates all of these
desired features. It contains
- the latches
- mask register
- status fence register
- priority encoder
- vector hold register
- clear control
- incrementer
- comparator
- interconnection logic for expansion
One device handles up to eight interrupt sources.
Figure 4-29 Am2914 block diagram

The instruction set for the Am2914 is shown in Table 4-2,
and a program flow is shown in Figure 4-30 which diagrams
where, within a microprogram structure, the various Am2914 instructions
could appear.
Table 4-2 Am2914 Instruction Set

Figure 4-30 Sample usage of Am2914 instructions (flow)

|