INTERRUPT CONTROL UNIT

Interrupt presented to control unit

Clocks

 

 

Interrupt presented to CPU

5

 

 

 

 

INTA

4

 

 

IDLE

2

Cascade Mode Only

 

INTA

4

 

 

 

IDLE

5

 

 

READ IP

4

 

 

IDLE

3

(5 if not cascade mode)

 

READ CS

4

 

 

IDLE

4

 

 

PUSH FLAGS

4

 

 

IDLE

3

 

 

PUSH CS

4

 

 

PUSH IP

4

 

First instruction fetch

IDLE

5

 

 

 

 

from interrupt routine

Total 55

A1212-A0

Figure 8-3. Interrupt Control Unit Latency and Response Time

8.4PROGRAMMING THE INTERRUPT CONTROL UNIT

Table 8-3 lists the Interrupt Control Unit registers in master mode with their Peripheral Control Block offset addresses. The remainder of this section describes the functions of the registers.

Table 8-3. Interrupt Control Unit Registers in Master Mode

Register Name

Offset Address

 

 

INT3 Control

3EH

 

 

INT2 Control

3CH

 

 

INT1 Control

3AH

 

 

INT0 Control

38H

 

 

DMA0 Control

34H

 

 

DMA1 Control

36H

 

 

Timer Control

32H

 

 

Interrupt Status

30H

Interrupt Request

2EH

 

 

8-11

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Intel 80C188XL Inta Idle Read IP, Read CS Idle Push Flags Push CS Push IP, Programming the Interrupt Control Unit