🚀 go-pugleaf

In article <1992Oct7.200256.12595@menudo.uh.edu> SINARRWB@admin.uh.edu (BELL, ROBERT W.) writes:
>
>Hola,
>
>        Ok, here is the deal.  Windows 3.0, mouse com1, serial com2,
>    have serial card...  I want/need to install an additional serial
>    card to attach an external modem to it.
>
>    com1: irq4   Mouse..
>    com2: irq3   Serial Connection (to a Vax)
>    com3: irq4   Serial Connection (to a modem, dial-out)
>    com4: irq3
>
>        I need to be able to use my mouse, and both serial ports !
>    What can I do in this situation ??  I know I could go buy a
>    new mouse with its own card, and/or internal modem.  Is there
>    anything else I can do ??  And, could someone clue me in as to
>    WHY there is this current irq mapping ???  Can it be hacked ?
>
>Bob
>

Unfortunately you are sort of stuck. COM1/COM3 both share IRQ4
(typically), and COM2/COM4 share IRQ3 (typically). Under DOS you
can not share interrupts like this and have everything work
together very well. One solution is to somehow find a way to get
your mouse onto IRQ5 or 7 or 9, or one of the other IRQ's that does
not use the COM port at the same time; or some other high traffic
I/O piece of hardware. You see, the mouse itself will generate
between 30 and 200 interrupts per second depending on the internal
settings of the mouse driver and interface with INT 33h. This
precludes sharing with high traffic devices like COM ports. Too
much competition...

...Paul

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