INTERRUPT CONTROL UNIT

Register Name:

In-Service Register

Register Mnemonic:

INSERV

Register Function:

Indicates which interrupt handlers are in process

15

I

I

I

I

N

N

N

N

T

T

T

T

3

2

1

0

 

 

 

 

DD M M A A 1 0

0

T

M

R

 

 

 

A1192-A0

 

 

 

 

 

Bit

Bit Name

Reset

Function

 

Mnemonic

State

 

 

 

 

 

 

 

 

 

INT3:0

External

0000 0

A bit is set to indicate that the corresponding

 

 

Interrupt In-

 

external interrupt is being serviced.

 

 

Service

 

 

 

 

 

 

 

 

DMA1:0

DMA

0

This bit is set to indicate that the corresponding

 

 

Interrupt In-

 

DMA channel interrupt is being serviced.

 

 

Service

 

 

 

 

 

 

 

 

TMR

Timer

0

This bit is set to indicate that a timer interrupt is

 

 

Interrupt In-

 

being serviced.

 

 

Service

 

 

 

 

 

 

 

 

NOTE: Reserved register bits are shown with gray shading. Reserved bits must be written to a logic zero to ensure compatibility with future Intel products.

Figure 8-10. In-Service Register

8.4.6Poll and Poll Status Registers

The Poll and Poll Status registers allow you to poll the Interrupt Control Unit and service inter- rupts through software. You can read these registers to determine whether an interrupt is pending and, if so, the interrupt type. The registers contain identical information, but reading them pro- duces different results.

8-19

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Intel 80C188XL, 80C186XL user manual In-Service Register, Inserv, Indicates which interrupt handlers are in process