Re: TI Graph Link Errors
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nonononono...
2e8, etc, are the memory addresses used for the com ports... IRQs are
different. The port writes to the address, then signals an interrupt (on an
IRQ line) to indicate that there's something there... Software can do the
same. Its OK for 2 devices to share an IRQ, as long as they're not using
the same address and the IRQs aren't signalled at the same time.
Example: The graph-link. Moving the mouse (com1, 3f8 IRQ4) or clicking
while sending data to the graph-link (com3, 3e8 IRQ4) is not OK b/c both
devices (mouse, graph-link) are signalling to the processor (at the same
time) that data is available, read it. However, its OK to use just one at a
time because the IO addresses are different. (There are some exceptions to
this, Windows keeps the COM1 port active 100% to poll the mouse). I can use
my Zip drive (LPT2, 278 IRQ5) and my Sound Blaster (SB32, 220 IRQ5) on the
same IRQ, just not at the same time.
Hope my $0.15 clears things up. Any questions, mail me & I'll explain
further...
At 21:44 8/1/96 GMT, you wrote:
>My computer has for separate IRQ's for 4 COMports... 2e8,2f8,3e8,and
>3f8.
>
>I am pretty sure I had to set hardware jumpers, but I don't remember
>if I actually did anything or not... It should be possible, check the
>docs that came with your IO card.
>
>Jason
>
>
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