I have an old Apple LaserWriter 4/600 PS printer that works great. It uses an 8 pin mini DIN serial cable. I have a G4 Apple computer with USB and FW ports. I need some sort of adapter to hook these two work horses together. Is there such an animal? Is there another way?

Try this
8 Pin USB Manufacturers & Suppliers (http://www.globalsources.com/manufacturers/8-Pin-USB.html)

Do you know if your connecting via Localtalk or true serial.

You might actually have to get 2 converters. One to convert Rs422 to Rs232 and then RS232 to USB.

But, first make sure a serial driver is available for the old printer and how long Apple plans to support it.

There were Ethertalk to Localtalk converters that put Localtalk printers on the Ethernet network back in the day, but Apple may have depreciated that protocol now. Asante used to make the converters, but you needed the Localtalk connector kits.

Well I tried that Cables To Go site and did not see any kind of 8 Pin Mini DIN to USB adapter. Then I tried chatting with a technician and he told me that they don't have anything that would work and that he doubted that any other company would carry such an item either. I even asked whether two adapters together might do the job but he said no. It seems strange that there isn't an adapter for a job like that. I mean after all, both the computer and the printer are made by Apple. :(

This might work:

EasySync USA (http://www.easysync-ltd.com/)

The ES-U-2001 : Single Port USB-RS422/RS485

You;ll have to fins the serail cable and wire it properly.

Apple use RS422 which is SOME cases worked with just some wiring changes. One example is the modem cable that Apple used, but I has a device that would not work by jumping because the serial voltage levels were too low.

Serial when it was initial introduced uses +-25 volt signal levels. They reduced it to +-12 and then to +-5. That's whay there is varied performance among devices. Voltages between +-3 are indeterminate.

USB powering has an additional hurdle. There is only 5 watts or 0.1 watts available depending if you're a main port.

Can you ost the pin assignments for the printer?

I've been down this road with apple products, although not with OS X. That's why it's EXTREMELY IMPORTANT that a driver is available.

Here is another ressources:

Apple serial connection (http://www.jneuhaus.com/applserl.html)
Mac Serial Cables - Apple MAC Serial Cable MAC serial Cable Mini Din 8 Straight Through Apple Cable Apple Cables mac serial cable apple serial cable apple serial cables (http://www.national-tech.com/catalog/macserialcables.htm)

With a little more searching, I found a ready-made adpater:

USB  Twin RS-422 Mini-DIN8 Serial Adapter (http://www.psism.com/usa28.htm)

Nice researching there KISS. I will try calling the company as the photo of the adapter is a little small for details. Thanks very much this really looks like the solution.

Well I finally got through to a company called PSISM. They sell a USB cable with Twin RS-422 Mini-DIN8 Serial Adapter, Model #:USA28XG. It's $90 a lot more then I would have expected.

I know, I got a P2015dn HP printer (Postscript, PCL6) and duplexing with USB and Ethernet for $250.