🚀 go-pugleaf

George Durbridge (gdurb@melbourne.DIALix.oz.au) wrote:
: Can you free up an irq by moving your mouse to a bus port ?  The bus 
: cards are cheap enough at swap meets and Microsoft mice run on them OK (I 
: don't know about others) but your kernel would need to support it.  But 
: Dimitri's point is still good: are you actually _using_ com3 ?

The mouse is a bus mouse, but the IRQ range is 2-5. The modem is on
COM4, so that's IRQ 3 gone. (Can't put the modem elsewhere, as COM1
and COM2 are on the motherboard with UART 16450s, COM3 is a 16450 and
COM4 is the 16550.) Network card has a range of 2-5. Soundblaster uses
IRQ 5 for the MIDI (whatever that is), and the tape backup unit shares
this IRQ channel. So I've put the network card on
IRQ 2 and the mouse on IRQ 4, which conflicts with COM3. The network
is up all the time, so I can't share that with anything. Usually I
don't use COM3 for anything, so the mouse is okay on IRQ 4.

So if I want to put a serial terminal on the system, it has to go
through COM3 or COM4. COM4 is the modem and is un use a fair bit. COM3
shares with the mouse and I only use that for X-Windows, so that looks
to me like a likely candidate for sharing. Which is what I do. So if I
want to use the serial terminal, I uncomment the line in /etc/inittab
and reboot. If I want X-Windows, I comment the line in /etc/inittab
and reboot. I don't use X-Windows all that much, and I'm starting to
use the serial terminal more and more. 

As money generally goes on the mortgage, I make do with what I have.
At the moment, swapping and rebooting for X-Windows isn't too onerous.
When it gets onerous, I will do something about. My initial thought is
to buy a top of the line intelligent serial card, which will handle
multiple COM ports on a single interrupt. This will help me out now,
and one day when I do upgarde the rest of the hardware, I can still
use it to good effect.

As for the high range of IRQ channels, IRQ 8 is in use by the clock,
IRQ 9 is the cascade from IRQ 2, so they are both unavailable to me.
10 is free, but nothing I have lets me use it. 11 is used by the
Soundcard too (it's greedy - uses two IRQ channels). 12 is the
scanner, 13 is unavailable as the coprocessor uses it, 14 is used by
the hard disk contoller, and 15 is free, but nothing I have lets me
use it.  If I'm wrong on any of this stuff, please let me know so I
can make adjustments.

Regards 

Henry
*****
hgriggs@mpx.com.au
http://www.mpx.com.au/~hgriggs
Sydney, Australia.