View Full Version : Dayton Hamfest - We saw a PDP-8/I !

May 22nd, 2009, 07:32 AM

Just got back from the Dayton Hamfest, and wanted to report.

First, I have to say that the Dayton Hamvention, while the largest hamfest in the US (perhaps world) did not meet my expectations for vintage computers. I have seen more vintage stuff in Baltimore. There was (as you can expect) lots of radios and antennas.

So, on Saturday, they are having the traditional rain showers and people are struggling to get out of the rain or cover their gear. Friend and co-pilot Maki noticed a machine a guy was getting ready to put away and stopped me. It was a PDP-8/L!

For those not in the know, a PDP-8/L was an early PDP-8 that used ‘flip chips’ – individual logic circuits, on small circuit boards. The backplane that they plugged into was wire-wrapped to complete the circuit. It seemed about 5 or so levels deep – very impressive. There must have been about 30-40 flip chips in the chassis – it was full. . It had 4K Words of memory.

I tried to get out of the guy where he got the PDP-8/L, but there were some communication problems (he was Canadian). He said he got it at ‘a scrappers’, which I think means junkyard or recycler.

The 8/L was in rough shape (dusty/dirty), and the cables to the expansion bus (posi-bus) were cut, but the guy said he wanted to get it running. He wouldn’t entertain selling it too me but let me flip the switches and look at it for a while. Maki took some pictures, that I’ll post when he gets them to me.

A small crowd gathered and someone mentioned that there was a PDP-8 clone you could build. I mentioned that both Maki and I had built one. The sky grew darker so we had to run for it.

So that was the highlight of the Hamfest for me (since Vince couldn’t make it).


May 26th, 2009, 07:32 AM
Hmmm.... Missed seeing the PDP-8 but not much else as far as computers. Still wish things hadn't come up. Maybe the days of vintage computers there are about done.


May 26th, 2009, 08:54 AM

Yeah, old age made me think it was an 8/I, but it was an 8/L.

Vince, we were sorry not to meet you.

Anyway, pictures are in my album, links below:

(left to right) Me (dunbfounded by wirewrap), the owner and his wife


Top view - look at the flip chips!


pdp-8/L with owner, dayton weather in background


pdp 8 topview - that's all wirewrap!


pdp8 owner and his wife - nice people, they tolerated me to brave the oncoming weather.



May 26th, 2009, 11:57 AM
Thanks for the pics. The 8/L is a nice machine, easier to carry than the 8/I

May 26th, 2009, 02:27 PM
Very cool system and very ominous weather in the background lol. Looks very similar to our fests down here and I know the reaction of folks with those clouds scrambling around to get their gear up out of the incoming rain.