Having trouble using all your peripherals in Writelog at the same time?
Don't have enough ports for it? One of the biggest problems is resolving up
the IRQ assignments and addresses, an old PC limitation. Well, it can be
done! After some experimenting, here's my setup, with port assignments,
IRQ's and base addresses for all ports. I hope this may be useful for other
Writelog users. It works really well on my PC, a home-made Pentium 133.
Port - IRQ - Base - Purpose
COM1 - 4 - 3F8 - Mouse
COM2 - 3 - 2F8 - Packet
COM3 - 11 - (PCI) - 56k internal modem on PCI bus
COM4 - 9 - 2E8 - Rig control (IC-756)
COM5 - 12 - 2F0 - FSK (RTTY) out
COM6 - 5 - 3E0 - PTT line for PSK31
LPT1 - 7 - 378 - Printer, ZIP drive
LPT2 - * - 278 - CW keyer, PTT line for DVK, antenna switching
Sound - 10 - Soundblaster 64AWE
*Note: LPT2 does not use its normally assigned IRQ5, making the interrupt
available for COM6. Since LPT2 only processes outgoing signals, it does not
need an interrupt.
Note that most software does not recognize COM ports higher than 4.
Luckily, Rttyrite does (Writelog itself does not for rig control or
COM1, COM2 and LPT1 are on the motherboard.
COM3 is assigned to the internal Winmodem on the PCI bus (Winmodems cannot
be assigned ports higher than COM4, oddly enough).
COM4 and LPT2 are on an 8-bit card (Everex EV-170).
COM5 and COM6 are on a 16-bit card (SIIG Model IO1813).
I think the Everex EV-170 board is no longer available. I guess any 2S/1P
card will do as long as it allows you to set up only one COM port (disable
the other) and a non-interrupt parallel port. Shop around. The SIIG card is
currently available at CompUSA for $39.95. It uses true 16550 chips. Other
boards may do, but make sure they can use high IRQ's AND high port
addresses - some only give you the high IRQ's.
If you have a PS/2 mouse, it typically uses IRQ12. Since using a mouse port
frees up COM1, that is actually desirable. Just assign COM5 to IRQ5 and
sacrifice COM6, as you won't be needing it. You'll still need the second
serial port card because the standard one most likely won't let you assign
the proper base address for anything other than COM 1 through 4.
Of course there is some additional hardware involved:
- Level shifters for FSK, CW and the PTT line (simple 2N2222's or equiv.)
- A little home-brew relay box that switches the rig's mic input from the
microphone to the sound board output when either COM6 or LPT2 assert the
- Rig control level shifter (home brew or Icom CT-17 or whatever brand
- a coax relay box for antenna switching (still on the project list)
There is actually an order of priority among IRQ's (which is somewhat
non-intuitive), but for all intents and purposes that doesn't matter for
Have fun, see you in the pile-ups!