QuestionAnswerIRQ 0SYSTEM TIMERIRQ 1KEYBOARDIRQ 2CASCADED WITH IRQ 9IRQ 3COM2 AND COM4IRQ 4COM1 AND COM3IRQ 5LPT2IRQ 6FLOPPY DRIVE CONTROLLERIRQ7LPT1IRQ8REAL TIME CLOCK
4
W
COM1 and COM3, IRQ4
IRQs 3 is reserved for the COM1 port.
COM1-IRQ 4, memory addresses 03F8-03FF COM2-IRQ 3, memory addresses 02F8-02FF COM3-IRQ 4, memory addresses 03E8-03EF COM4-IRQ 3, memory addresses 02E8-02EF pg. 396
Hi, correct combination of default combination of COM ports and IRQ is given below: 1. com1 and com3 - IRQ4 2. com2 and com4 - IRQ3 below link can easily explain the answer in details. You can even see this in device manager properties. i.e. mycomputer > properties > device manager> IDE/ATA controller > resources > irq=20 link : http://www.webopedia.com/quick_ref/IRQnumbers.asp
By default, the IRQ for the floppy disk controller is IRQ 6.
By default IRQ 7 is assigned to LPT1.
From: http://www.techadvice.com/tech/C/ComPort_TS.htmCom1, IRQ 4, address: 3F8Com2, IRQ 3, address: 2F8Com3, IRQ 4, address: 3E8Com4, IRQ 3, address: 2E8
COM1 is assigned 3F8h and uses IRQ Channel 4, COM2 is assigned 2F8h and uses IRQ Channel 3, COM3 is assigned 3E8h and uses IRQ Channel 4
LTP1 should use IRQ7.
IRQ 0 - System timer. IRQ 1 - Keyboard. IRQ 2 - Cascaded signals from IRQs 8-15. IRQ 3 - COM2 (Default) and COM4 (User) serial ports IRQ 4 - COM1 (Default) and COM3 (User) serial ports IRQ 5 - LPT2 Parallel Port 2 or sound card IRQ 6 - Floppy disk controller IRQ 7 - LPT1 Parallel Port 1 or sound card (8-bit Sound Blaster and compatibles) IRQ 8 - Real time clock IRQ 9 - Free / Open interrupt / Available / SCSI. Any devices configured to use IRQ 2 will actually be using IRQ 9. IRQ 10 - Free IRQ 11 - Free IRQ 12 - PS/2 connector Mouse. IRQ 13 - ISA / Math Co-Processor IRQ 14 - Primary IDE. If no Primary IDE this can be changed IRQ 15 - Secondary IDE These are just a set of standard IRQs. For much more detail check our Ralf Brown's list located at http://www.cs.cmu.edu/~ralf/files.html
A floppy disk typically uses IRQ6 (that is on windows server 2003)
It can be switched off in BIOS of your PC. In Apple Macintosh there's no COM1 at all.