This is a small list of 3Com dongle pinouts I've put together. Use at your own risk.
3C-PC-TX-CBL for use with
3C574, 3C575 card only
Looking into the card jack going from left to right:
1: LED + (If you have the dongle connector open
and plugged in, with the cable towards
you, this is the lefmost top pin.)
2 (leftmost bottom pin)
5 Blue/white (RX+)
6 Blue (RX-)
7 Orange/white (TX+)
8 Orange (TX-)
15 Gnd (LED -)
This works fine on my 3C574 card at 100Mbps. Use good cable and keep it short for best results.
I have not personally tested the 3C575 yet. I've got the card,
but my older laptop does not support CardBus, which the
3C575 apparently requires. When I get a chance, I'll double
check on the 3C575, or if you have tested this, let me know.
3Com Info: 3COM PCMCIA NIC models: 3C562, 3C562B,
3C562C, 3C562D, 3C552D, 3C563, 3C563B, 3C563C, 3C563D, 3C589C, (RJ45 cable
only, not coaxial), 3C589D, CCE589ET, 3CCE589EC, 3CXE589ET
Rightmost pin to (rj-45) pin 6,next pin to rj-pin-3, next pin to
next pin to rj-pin-1.
Skip 2 pins LED + , skip 5 pins LED - (LED + and - may be inverted.)
Of course, this means that you can't 'cheat' and build a universal (or at least 3C589 + 574/575) cable by merely jumping the correct pins. You could by using a couple of switches mounted on an RJ-45 conenctor shell, but at that point it becomes large and ugly.
Elusive 3com older PCMCIA Modem pinout:
Look into the phone cable to pcmcia jack connector. This has a phone plug on one end and the flat connector that plugs into the pcmcia card on the other. Looking into the pcmcia end, copper connectors on bottom, plastic with small cutouts on top, the righmost two pins are the ones you need...at least for USA. I can't say for any other countries, but the connector I have has the next two pins pulled, in other words, empty holes w/o pins in them.
Inside an actual 3com cable, on the solder side, the two leftmost pins are the top and bottom pins. Top is blue (tip), bottom is dark blue with a white stripe (ring.)
The connector is the same as for 3com ethernet cards of the same era, but the cutouts are different. This means you cannot directly modify an ethernet dongle into a phone dongle w/o doing some very (very very) precise plastic cutting. You are more likely to wipe out your connector than to get the cutouts right. If you try this, and it works, great. If it doesn't, I warned you and take absolutely no responsibility for anything that happens to your connector, modem card, ethernet card, laptop, desktop, health, wealth or life. Not only that, I reserve the right to laugh meanly and/or say "I told you so." in various patronizing ways.
The cable i used to figure out this pinout is a 3com original, labeled:
This cable 'should' work with:
Sportster 1336, 1626, 3013, 3CCEM556B/C/T, 3CCM156, 156B, 356, 550, 556, 650, 656, 756, CC1288, 1366, 1560, 1560i, 2560, 3288, 4288, 4336, 5560, 6144, 6288, CCEM3288C/T, 3336T, CM1561B-US, EM1144T, 3C562C/3C563C (combo ethernet/modem)
paul at noteablecomputers daht com
Please feel free to send any other pinouts you have.