Okay, here's the skinny... 3Com's PalmPilot is a great tool, but the fact that 3Com doesn't publish the cable specs bugged me and a standard RS-422 to PC 9-Pin Serial (PC 9) didn't seem to work at all. Briefly, the Pilot comes with, by default, a PC serial connector...making it perfect for connecting to a PC. The problem is that the serial port interface on a PC is configured very differently from that of a Mac and therefore to use your PalmPilot with a Mac, you have to buy a special 3 Com package called the "MacPac", usually about $30US. What's in this MacPac? Well it does come with Mac ports of 3Com's desktop software, which is nice, and it comes with a special 3Com-designed PC serial-to-Mac serial converter (see Figure 1). Well, even if they have $25 in software development costs for each MacPac sold (which I'm sure they don't), I'm not so sure the little connector is worth $5, and even if it were, they should offer it separately since there are applications where all you actually need is that PC/Mac serial cable converter to make your PalmPilot useful under the MacOS (using it under VirtualPC, for example. I use mine under VirtualPC mainly because we use the Netscape Calendar Server at my office and Netscape's PalmPilot calendar-sync application comes in only the Win95/98 flavor ...ouch.) I make no broad assertions about the converter cable design that comes with the MacPac, it very well may be that the MacPac cable is, in fact, a style of cable that is used in other applications that I am simply not aware of, but my small amount of research showed very definate differences in the cable-spec that Apple publishes for their serial connectors and the cable converter that 3 Com uses. At any rate, I decided to take a look at the serial converter cable that came with someone else's MacPac and mapped it's pinout. The cable should be relatively easy to make...mine works great. If you have a multimeter that measures resistance (in Ohms), you should have no problem converting a standard PC serial cable to a MacPac cable using the pin diagram below. Have fun! Figure 1: The 3Com MacPac© Converter Cable It looks like a standard PC-Mac serial converter, but it isn't...   Figure 2: The MacPac Cable Pinout Diagram This perhaps-cryptic diagram is a graphical representation of the 3 Com MacPac cable pinout. The two large graphics obviously are the cable ends and the colored lines show how the pins on one end should be connected to the pins on the opposite end (NOTE: the diagram above depicts the pin grouping as though you are holding the cable and looking directly at the pins of the cable ends.) Use the multimeter to make sure all the connections are made properly. Genders: Both the PC-9 (the d-shaped one) end as well as the Mac RS-422 (the round end) should be male in gender. Some of you astute would-be MacPac cablemakers have pointed out the oddity of pin 1 on the PC9 connecting to both pins 8 and 4 on the Mac side. To tell you the truth, I've no idea why 3Com's developers chose to do this, though I've got a couple ideas. In possible explanation, let me just quote an email from a chap in Australia who wrote to me regarding the creation of his own MacPac cable (via instructions provided from this page): Date: Mon, 18 Jan 1999 09:40:41 +0800 From: Rod Kevill To: Colonel Panick Subject: Re: Palm III to Mac connector Hi Neil, All working now! That Pin 3 TxD now turns out to be Pin 1, a handshake signal which they pull low by connecting to GND... <snipped for brevity -ed.> Many thanks for your assistance - much appreciated! Cheers, Rod .--------------------------------------------------------------. | Rod Kevill, Lecturer Mobile: XX XXXX XXXX | | Centre for Educational Advancement Tel: XX XXXX XXXX | | Curtin University of Technology Fax: XX XXXX XXXX | <sig snipped and edited for privacy -ed.> ...now, this may or may not be the actual reason for the doubling of those wire, but I just wanted to point out to those who might look at that scratching their heads wondering if I'd lost my mind that yes, though I lost my mind years ago, that wire does in fact go to two pins. :) Also, please note that he's using it on a PalmIII organizer, so obviously they haven't changed the HotSync cabling specs for their latest version of the Pilot...which is cool.   Figure 3: The Cord Nearing Completion You can just cut a standard Pc-Mac serial converter in two and rewire if you like... ...or if you prefer, buy a kit like the one we used that just requires some minimal assembly.     For more information on cable and pinout specs, check out the online Hardware Book. Acknowledgements Big thanks to Djungi Karjadi of Roscor for pointint out my mistake in the pin numbering for the 9-pin PC serial cable and for sending in the corrected diagram! The End