Interrupt Help
26-Oct-91 15:19:40
Sb: #26113-Interrupt Help
Fm: Paul E. Hansen [SysOp] 76702,475
To: Bob Gaudio 71230,2043
This message turned up in search, but its forum couldn’t be identified from the original transcript, so it may not be linked into its thread.
In the XT/AT environment the standard addresses and IRQs are:
COM1 03F8 IRQ4
COM2 02F8 IRQ3
COM3 03E8 IRQ4
COM4 02E8 IRQ3
Note that COM1 and COM3 share IRQ4, while COM2 and COM4 share IRQ3. This is
'built into' the original IBM architecture. (Actually, only COM1 and COM2
were originally defined.)
All of PPI internal modems are set to function at the standard addresses
and interrupts shown above. There is no way to alter the IRQ or address in
the modem. If you have a mouse on COM1, then you cannot use a modem on
COM3, it must either be mapped to COM2 or COM4. If you already have a
serial port installed in your computer at COM2, then the only place to
install the internal modem is as COM4 in your situation.
If you have a conflict with another device, then the usual symptom is that
you may be able to dial out with the modem, but nothing will appear on the
screen once a connection is made.
You will have to be a bit more definitive in your description of the
problem you have had in calling the PPI BBS before I can attempt to
determine why you might be having a problem.