After all my hassle of getting my old HP LaserJet 2100 to work with Leopard -- including installing a JetDirect card for Ethernet with AppleTalk -- Apple removed AppleTalk from Snow Leopard. So, I was right back where I started.
Well, not quite. At least I had the JetDirect card. With just a little more trouble, I should have been able to connect through TCP/IP, the card's other protocol. Only, that wasn't working either, despite my following helpful instructions from around the Web.
I finally found someone who had successfully navigated the whole maze for a LaserJet 2100. You can read Maria Langer's original post here. But I'll try to simplify it for you.
Basically what we're going to do is change the Mac's IP address so it will see itself and the printer as being on the same network. A better solution would probably be to change the IP address of the printer, but I'm told that requires the HP utility for either Windows or OS 9, which not everyone has. This may be a second-best solution, but it works fine -- as long as you are not using the Ethernet service for anything but connecting to your printer. (For all other networking, I use Airport, not Ethernet.)
If you are using Ethernet to also connect to other computers or the Internet, you cannot use this solution! Go find something that instead tells you how to change your printer's IP address. If you do what I tell you, you'll be disconnected!
[Update: This shows how little I know about Ethernet. According to a commenter on this post, he simply went to Network in System Prefs and set up a second Ethernet service to handle the printer separately. With that, my instructions caused no problem with his Internet connection.]
OK, here are the steps.
1. Make sure that your Mac and your printer are turned on. You also need to see an Ethernet service listed in your Network preferences panel. If there isn't one, click on the plus sign and add one.
2. You need to know the IP address of your printer. If you haven't messed with your network setup, then it's probably the default of 18.104.22.168. To find out for sure, you can print out a configuration page by pressing the printer's two buttons at the same time -- the Go button and the Job Cancel button. The address will appear on the second page that prints. Note: you can't do this right after turning on your computer and/or printer, but only after a minute or two. If you try too soon, you'll instead see 0.0.0.0.
If you have messed with your network setup and for some reason need to return to the printer's default settings, you can do a "cold reset." For the 2100, turn off the printer, then turn it back on while holding down the Job Cancel button. Keep it pressed till the printer lights come on, then release it at once. (If you hold it down another 20 seconds, you'll lose your printer's internal statistics.) Then wait a minute or two, if you want to check the result by getting a configuration page.
3. In your Network prefs, set the Configure menu to "Using DHCP with manual address." Then in the IP address slot, enter the same IP address as your printer, except lower the last number by one. So, if your printer is at 22.214.171.124, the address you'd enter here would be 126.96.36.199. Do not enter the exact same address as your printer's! (There are no doubt other values that will work here, but I'm just describing what Maria did and what worked for me too.)
4. Go to the Print & Fax preferences pane, and click on the plus sign to add a printer. At the top of the dialog box, click on "IP." As the protocol, choose "HP JetDirect - Socket." Enter the IP address for your printer. Give the printer a descriptive name.
At this point, your Mac should have already automatically filled in "Print Using" with "HP LaserJet 2100 series," which it got by connecting with your printer. If you instead get "Generic PostScript Printer," this means your Mac is not connecting, and you won't be able to print, regardless of whether you finish adding the printer or not. So, you'll need to try something else.
5. If everything's OK, just click "Add," and your Mac will do the rest. Oh, and don't forget to right-click on the printer in the list if you need to specify it as the default.
If you ever need to return to the Mac's default Ethernet setup, change the service's Configure menu to "Using DHCP" without "manual address." Or just delete the service and add a new one.
Now, if I can just get my old scanner and DVD burner to work.