DESCRIPTION OF PIN FUNCTIONS
PIN NO.
38
NAME
Serial Port
Interrupt
Request
SYMBOL
IRQ4
BUFFER
TYPE
O24
DESCRIPTION
FDC37C665GT (Motherboard application):
IRQ4 is the interrupt from the Primary Serial
Port (PSP) or Secondary Serial Port (SSP)
when the PSP or SSP have their address
programmed as COM1 or COM3 (as
defined in the Configuration Registers). The
appropriate interrupt from the Serial Port is
enabled/disabled via the Interrupt Enable
Register (IER).
The interrupt is reset
inactive after interrupt service. It is disabled
through IER or hardware reset.
FDC37C666GT (Adapter application):
PSPIRQ is a source of PSP interrupt.
Externally, it should be connected to either
IRQ3 or IRQ4 on PC/AT via jumpers.
FDC37C665GT (Motherboard application):
IRQ3 is the interrupt from the Primary Serial
Port (PSP) or secondary Serial Port (SSP)
when the PSP or SSP have their address
programmed as COM2 or COM4 (as
defined in the Configuration Registers). The
appropriate interrupt from the Serial Port is
enabled/disabled via the Interrupt Enable
Register (IER).
The interrupt is reset
inactive after interrupt service. It is disabled
through IER or hardware reset.
FDC37C666GT (Adapter application):
SSPIRQ is a source of SSP interrupt.
Externally, it should be connected to either
IRQ3 or IRQ4 on PC/AT via jumpers.
This interrupt from the Floppy Disk
Controller is enabled/disabled via bit 3 of the
Digital Output Register (DOR).
Primary Serial
Port Interrupt
PSPIRQ
O24
37
Serial Port
Interrupt
Request
IRQ3
O24
Secondary Serial SSPIRQ
Port Interrupt
O24
40
Floppy
Controller
Interrupt
Request
FINTR
O24
6
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