Mike's PCjr Page

The cluster adapter seems to be the only networking sidecar released for the PCjr. It appears to have a BNC connector, but I assume it was meant to connect to ancient networks. With an RJ45 Transceiver and a packet driver (which someone would have to write), would it be useful today?

Have you also been watching that one that keeps popping up on eBay that nobody ever bids on?

'Cause I keep thinking about bidding on it, but can't decide if I'd actually have a use for it, haha.

The IBM Cluster Adapter is designed to attach a PCjr to an IBM Cluster network. "Cluster" if a very specific term here - it was a networking technology that IBM sold for a brief period of time and it is not compatible with any other networking technology. You can only talk to other machines with a similar adapter. There was an ISA version of the Cluster adapter as well.

It is not Ethernet. Wipe out those thoughts of "RJ45 Transceiver" and packet drivers. On Ethernet an AUI port on the card allows for the use of external transceivers but no such thing exists for Cluster and the terminology "Rj45 Transceiver" is wrong - it is more correct to call such a device a 10BASE-T transceiver. A packet driver could be written that emulates Ethernet over the Cluster frame format. You need the Cluster technical reference to figure out what work is required.

To make a PCjr with Cluster internet accessible you would need to have a gateway machine that has both Cluster and another networking device (serial or Ethernet). A Linux machine would be great for that, but Linux machines don't know anything about Cluster. Cluster was dead 7 years before Linux was started.

Cluster is a power hog. Do not run a Cluster adapter without a power sidecar in-line ahead of it. You will melt/fry your internal power supply card.

So you're saying Cluster is a cluster?

I think they are cool. I paid way too much for my setup, but that was the only way to find out what it does. At some point I need to post the software and the technical reference manual before they get lost to the sands of time.

As far as the rest of the world is concerned, it was a flop. Another IBM proprietary technology that quickly failed.

Would it be useful to get it for the case, and maybe stick one of the new production memory sidecar boards in it?

Also, have you had a chance to upload the documentation, or did the sands of time get them?

DO NOT gut a cluster adapter to make a jrIDE or the PCjr gods will find you. Gut a power sidecar, or a memory sidecar, those are much more common, and also no longer necessary, once you hook up a jrIDE.

Cluster documentation is at ftp://ftp.oldskool.org/pub/drivers/IBM/ ... chment.pdf but it's nothing special. The adapter comes with no software. I, too, would like to see the software and the technical reference manual...

Or even better, gut a dead sidecar, like one that had a barrel battery from something spill its guts all over at some point in the past.