CyberResearch PCIDIO 24H Manual De Usuario

 

There is only one IRQ level requested by this card, although it is a dual 
interrupt system.  The motherboard circuits will transfer INTA# to one of the 
PC IRQ levels.  The IRQ level is set by  the PCI plug and play BIOS and 
saved in the PCI controller. Users can get the IRQ level setting by software 
library. 

 
 
 
 
  
 
 
 
 
 

(*) Note: This interrupt is not available in PCIDIO 24H 

The PCI controller of PCIDIO 24H/48H/96H can receive two hardware IRQ 
sources.  However, a PCI controller can generate only one IRQ to PCI bus, 
the two IRQ sources must be distinguished by the ISR of the application 
software if the two IRQs are both used. 

The application software can use the “_dioxxh_Get_Irq_Status” function to 
distinguish which interrupt is inserted.  After an ISR is completed, users must 
check if another IRQ is also asserted, then clear current IRQ to allow the 
next IRQ coming in.   

The two IRQs are named as INT1 and INT2.  In PCIDIO 24H/48H/96H, INT1 
comes from P1C0, P1C3 or the event counter interrupt.  INT2 comes from 
P2C0, P2C3 or the timer interrupt.  However in PCIDIO 24H, INT2 only comes 
from timer interrupt. The sources of INT1 and INT2  is selectable by the 
Interrupt Source Control (ISC) Register. 

 

PCI 

Controller 

INTA# 

IRQ 

Flip-

Flops  

INT1 

INT2 

Clear IRQ  

INT1 
MUX 

P1C0 

~P1C0 & P1C3  

Event Counter 

INT2 
MUX 

P2C0 (*) 

~P2C0 & P2C3 (*) 

Timer IRQ