At 12:12 PM 9/29/97 +0930, you wrote:
>Extract From the AT Technical Refrence:
>
>IRQ's
>"An interupt request is generated when an IRQ line is raised from low to
high.
> The line must be held high until the microprocessor acknowledges the
interupt
> request (Interupt Service routine). Interupt 13 is used on the system
board and
> is not available on the i/o channel. Interupt 8 is used for the real-time
> clock."
>
>I also found that the standard printer port dose not conform to this, as
it has
> not got any latching device in the interface. It just passes the ACK
pulse from
> the printer's ACK pin. This pulse width is typicaly 5us.
>

Thank you for the information, but I still have one question, how does the
microprocessor ack the IRQ? I am looking at a diagram of the ISA bus and I
don't see any IRQ ack pin or anything like that.

Thanks again,
Sean

Sean Breheny,KA3YXM
Electrical Engineering Student