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Subject:
From:
David Gillett <[log in to unmask]>
Reply To:
PCBUILD - Personal Computer Hardware discussion List <[log in to unmask]>
Date:
Fri, 18 Dec 1998 10:15:12 -0800
Content-Type:
text/plain
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text/plain (41 lines)
On 19 Dec 98 at 0:43, Jun Qian wrote:

> David Gillett wrote:
>
> > [*] Actually, I usually put the serial mouse on COM2, external serial
> > device (modem, PDA, or whatever) on COM1, and internal modem on COM3
> > -- with a non-standard IRQ if there will be times when I want to use
> > both it and the device on COM1.
> >
>
> Is there any advantage to do this way? I put mouse on com1,
> external modem on com2. Am I wrong or just personal hobby?

  If those are all the serial devices you ever use, that works fine.
But what happens when you want to add a third device?
  Normally, it would install as COM3 and IRQ4 -- but the mouse is
already using IRQ4, ALL THE TIME.  So you either move COM3 to another
IRQ (subject to limitations of whatever COM3 port hardware you're
installing...), or you make the third port COM4.
  COM4?  Enough people have done this to reassure me that Win 9x
doesn't have the problems with this configuration that Win 3.x had.
But there is also a conflict between the port assignments for COM4
and an IBM video standard (top of the line in 1987!) that is still
emulated in cards from ATI or using S3 chipsets.

  I've built two machines which had graphics tablets -- which, like
mice, use their port's IRQ all the time.  In one case, I was able to
install the modem as COM3 IRQ12; in the more recent case, I was able
to use a PS/2 mouse and leave the COM ports for tablet and modem.

  I wouldn't say that you're "wrong" -- lots of people who get paid
to build computers put the mouse on COM1.  I've just found that when
I need a third COM port, for whatever reason, my options are simpler
and more robust if I have the mouse on COM2 instead.

David G

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