10BASE2 Networking

Alright, I know you all want to use the native 10BASE2 physical media with your VAX. Of course, your home network has twisted pair, i.e. 100BASE-T or 1000BASE-T. Well, for quite a while I used a transceiver on the AUI port on the back of my VAXstations. With this setup, I could connect directly to my home network. One of the transceivers was a little flaky though and wouldn’t connect to the network after bootup. I’d have to unplug it and plug it back in.

And there’s that nagging urge to use 10BASE2. So, I spent a while looking at protocol converters from companies like Black Box, but they were over $100. Then I stumbled on a Netgear hub called an EN104. It’s a 4 port hub with a coax connector on the back for a 5th port. I Iooked on eBay and, yup, over $100. Give me a break – this is old obsolete stuff you know. Be careful too. You might find one for $20, but odds are it’s an EN104TP which doesn’t have the coax port.

So, I looked up the CentreCom equivalent, an RH505BE. Only $15 on eBay and I can ditch the transceivers. Now I have a 10BASE2 segment with two VAXen and one PC connected to my 1000BASE-T network!

VAXstation 3100 External Cache

There’s quite a few websites that mention the VAXstation 3100 as having a 64 kB external cache. I’m not sure how that originally started – maybe it was because of DEC’s confusing naming conventions. You know, a MicroVAX 3100, VAXstation 3100, etc.

One day I had one of my VAXstation 3100’s apart and was identifying chips on the CPU board. I found the cache memory chips and looked up the part number printed on them. I came up with 32 kB of external cache. I could go back and take apart a VAXstation, take some photos, and post the picture along with a datasheet of the memory chips. Instead, I’ll just post the first page of Appendix D from my VAXstation 3100 Model 40 Owner’s Manual (#EK-266AA-OM-001).