PB 300/301/320 IRQ Availability

The available IRQs may vary depending on the system configurations. When determining available IRQs always check for printers, sound cards, CD-ROM drives and any other devices in the system.
 

Note
The Bolded lines are usually free IRQs except when it is used by the indicated or added devices.
 

IRQ

Description

Used

Handled By
0 Timer Click Yes Default Handles
1 Keyboard Yes Default Handles
2 Second 8259A Yes BIOS
3 COM2 or COM4 COM2 BIOS
4 COM1 or COM3 COM1 BIOS

5

LPT2 or Sound Card (If present)

Yes

BIOS

6 Floppy Disk Yes Default Handlers
7 LPT1 Yes System Area
8 Real-Time Clock Yes Default Handlers
9 Redirected IRQ2 Yes BIOS

10

Sound Card (If present)

Yes

BIOS

11

(Reserved)

Free 1

BIOS

12 PS/2 Mouse Yes Default Handles
13 Math Co-processor (If present) Yes BIOS
14 Fixed Disk Yes Default Handlers

15

Secondary Fixed Disk (If present)

Free 2

Default Handlers

 

1. If a PBTV4 card is installed then IRQ 11 is used.
 
2. If an IDE CD-ROM is used then IRQ 15 is used.
 


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