Serial Communication Between Macintosh and HP48

Preliminary Remarks

1. Kermit has been a beta program longer than I have had a Mac. It is also an exceptionally stable program for being such an old beta program. So don't mind the message about a beta release. It's not going to change soon, so far as I know, and I wouldn't worry.
2. Kermit doesn't have the friendliest, most graphical interface you've ever seen on your Mac. So what? It works well. I can not easily transfer binary files with the commerical program I bought to transfer files to my HP48. In terms of working, Kermit is more useful than that pretty program. Be calm, and it will work.
3. Kermit is the name of a popular frog. Completely different, Kermit is also the name for a certain protocol (a set of rules) for serial devices to communicate. So this is the language your Mac and your HP48 use to speak to each other. Different again is the program Kermit. The program named Kermit implements the protocol also named Kermit. In order for the Mac to "speak Kermit" it must run a program that knows Kermit. Like the program named Kermit. Confused already? Just try to keep straight these three meanings of the word Kermit.

If you need a cable, and want to make your own, the pinouts are in the manual [page 27-7 of HP 48G Series: User's Guide], in the FAQ, and on my page of pinouts. I got the parts from Jameco. For the HP48, I got these Jameco part numbers: 152469 for 2mm, 4 contacts connectors at 10 for 90¢, and 152493 female crimp pins for the connectors at 100 for $2. Don't buy with the crimp tool (I did) because a pair of needlenose pliers works much better.

How To...

0. Have HP48 (I have a GX) and Mac-to-HP48 cable already. Have a means to download, unbinhex, and extract files like Netscape and Mind Expander.
1. Download Kermit at http://www.umich.edu/~archive/mac/util/comm/kermit0.99190.cpt.hqx
   or other sites (Columbia University, the Kermit home site, UMich mac-archive comm directory or Info-Mac comm/term directory).
2. Launch Kermit (after de-bin-hex-ing and extracting). I didn't have to change any settings from the freshly downloaded copy of Kermit. However, if you have any problems, check your communication settings in the Settings menu. The most common problem is selecting the wrong port (not the one into which the cable is plugged). Use 9600, N/8, and the right port. All the other settings should be fine.
   
   As a troubleshooting tip, the last time I tested this, I had to turn AppleTalk off and use the printer port because the modem port wanted to use Apple Modem Tool and dial. Try the other port if you have a problem and the option. The extensions I suspect have these icons in Icon View:
   
3. Get the HP48 ready to receive. The serial cable should already run between the modem or printer port of the Mac and the HP48. Put the HP48 in Kermit client mode. On the HP48GX, use right-shift -> (GREEN-SWAP) as a shortcut. (I don't know the S series.)
4. Go to the File-Transfer menu and choose Send File from MacKermit. Pick the file, choose Ascii or Binary data for the sending as appropriate, and click on send. Away you go! To receive a file, choose Get File From Server, and know the name of the file on the HP. The keyboard shortcuts are S for Send and G for Get.

• As an interesting alternate, from the Window menu, open the Command window. This is the window to type in kermit-protocol commands directly. You don't need it for simple transfers using the File-Transfer menu. This is the window to trickier things. If you know CLI Kermit, you might like this window.

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Created: October 15, 1997
Last Revised: March 1, 1999

This URL: http://www.bme.unc.edu/~hope/linx/mac/mac-hp48.html
Copyright 1999 by Joni Julian