nedah
01-24-2001, 08:16 AM
IRQ and I/O conflicts
I recall seeing in the forums, references to IRQ and I/O conflicts (usually in relation to COM ports) but do not know how these are identified and resolved . Can someone please help me to a better understanding of this subject. If the answer is too long to be dealt with in the forum perhaps there are articles or books which can be recommended.
My understanding so far is:-
(a) A COMmunication port is a package of resources (i.e IRQ &/or I/O &/or DMA &/or Memory)
(b) Every “device” needs a COM.
(c) In the case of serial ports (devices), the convention is that one of the serial ports has a resource package consisting of IRQ4 and I/O address 03F8 - 03FF. This package is by convention known as COM1 but in theory the resource package assigned to that serial port could be quite different.
Now for my questions:-
1. I know there are only 15 IRQs but how many I/O addresses are there?
2. When I look at the Device Manager/View Resources on my computer the I/O range appears to be from 0000 - FCFF. What is the pattern of progression or, in other words, how do you get from 0000 - FCFF?
3. How can I discover (do I need to know?) the nature of all the “unknown devices” which appear to be absorbing a very large number of I/O addresses on my PC? (My OS is Win95, no games and only normal peripherals ie mouse, printer, scanner, zip drive and external modem)
4. When a peripheral device is attached to a serial port does that peripheral device have access only to the COM package (eg IRQ4 and 03F8 - 03FF) already allocated to that serial port or does the software which comes with the peripheral device allow the peripheral device access to a different COM packages?
Thanks to all you guys who spend so much time dealing with our questions. I didn’t get into computers until I retired and I am constantly amazed by the problems which arise. I look forward to finding out more about this area of resources.
I recall seeing in the forums, references to IRQ and I/O conflicts (usually in relation to COM ports) but do not know how these are identified and resolved . Can someone please help me to a better understanding of this subject. If the answer is too long to be dealt with in the forum perhaps there are articles or books which can be recommended.
My understanding so far is:-
(a) A COMmunication port is a package of resources (i.e IRQ &/or I/O &/or DMA &/or Memory)
(b) Every “device” needs a COM.
(c) In the case of serial ports (devices), the convention is that one of the serial ports has a resource package consisting of IRQ4 and I/O address 03F8 - 03FF. This package is by convention known as COM1 but in theory the resource package assigned to that serial port could be quite different.
Now for my questions:-
1. I know there are only 15 IRQs but how many I/O addresses are there?
2. When I look at the Device Manager/View Resources on my computer the I/O range appears to be from 0000 - FCFF. What is the pattern of progression or, in other words, how do you get from 0000 - FCFF?
3. How can I discover (do I need to know?) the nature of all the “unknown devices” which appear to be absorbing a very large number of I/O addresses on my PC? (My OS is Win95, no games and only normal peripherals ie mouse, printer, scanner, zip drive and external modem)
4. When a peripheral device is attached to a serial port does that peripheral device have access only to the COM package (eg IRQ4 and 03F8 - 03FF) already allocated to that serial port or does the software which comes with the peripheral device allow the peripheral device access to a different COM packages?
Thanks to all you guys who spend so much time dealing with our questions. I didn’t get into computers until I retired and I am constantly amazed by the problems which arise. I look forward to finding out more about this area of resources.