MC68306 Motorola, MC68306 Datasheet - Page 43

• Manufacturer Part Number: MC68306
• Description: Integrated EC000 Processor
• Manufacturer: Motorola

STATE 17
STATE 18
STATE 19
STATE 20
STATE 21
3.1.4 CPU Space Cycle
A CPU space cycle, indicated when the function codes are all high, is a special processor
cycle. In the 68EC000 core, CPU space is used only for interrupt acknowledge cycles.
Figure 3-10 shows the encoding of an interrupt acknowledge cycle.
The interrupt acknowledge cycle places the level of the interrupt being acknowledged on
address bits A3–A1 and drives all other address lines high. The interrupt acknowledge
cycle reads a vector number when the device places a vector number on the data bus.
The timing diagram for an interrupt acknowledge cycle is shown in Figure 3-11.
MOTOROLA
ACKNOWLEDGE
INTERRUPT
During S17, no bus signals are altered.
During S18, no bus signals are altered.
During S19, no bus signals are altered.
During S20. no bus signals are altered.
The processor negates AS and UDS /LDS.
1
1
1
Figure 3-10. Interrupt Acknowledge Cycle
31
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
MC68306 USER'S MANUAL
3
LEVEL
1 0
1
3- 11