I’ve decided to sell of a few PDP-8’s as the hoard is getting rather large at the moment and so I’m prepared to part with the following:

• PDP-8/M, 8KW core, M8650 serial UART, very clean machine in working order. This machine is currently listed on ebay here: http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=320762438517&ssPageName=STRK:MESE:IT
• PDP-8/E, 4KW core, M8650 UART, requires a full rebuild
• PDP-8/A, 16KW core, extended memory, serial, paper tape drive and controller (non DEC). Very clean and in working order
• RX8E + RX01 drives
• PC8E + PC04 paper tape
• DECmate III
• WP78 (aka a VT78)

Email offers to toby@pdp11.co.uk . Machines are located in UK

A new arrival in my collection was a fairly clean PDP-8/E chassis. The box came with no cards but I have sufficient spares to populate.

First step in rebuilding it is to strip it down and remove all the foam gunk before moving onto reviving the power supply.

Here are some pictures from the strip down

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This table details locations of cards on a PDP-8/L backplane. I’ve put it together to aid in working out what is missing from my 8/L. I believe it to be accurate but you are encouraged to double check!

Optional data break interface
Optional memory parity
Optional power fail
Optional high speed reader and/or punch

The following documentation is available as PDFs for the PDP-8/E (source Bitsavers)

	DEC-8E-HMM3A-C-D_MaintVol3.pdf	04-Jul-2002 02:11	26M	-
	DEC-8E-HR1C-D_8eMaint_Feb73.pdf	14-Oct-2003 23:39	13M	-
	DEC-8E-OCASA-B-D_CAPS8_UG.pdf	03-Jul-2003 01:14	9.6M	-
	PDP-8E_ECO_LOG_Dec74.pdf	31-Dec-2008 21:36	41M	-
	PDP-8E_IPB_Feb74.pdf	21-Nov-2007 19:01	826K	Illustrated parts breakdown
	PDP8E_MaintCourseHandouts.pdf	-

Here are a collection of You Tube videos featuring PDP-8s playing music:

A rather nice new arrival for my collection is a PDP-8/E. The machine is in 3 H960 racks and has a pair of RK05 drives and a pair of Magtape drives (with pertec interfaces).  The 8/E has an expansion box giving a total of 40 slots. The machine has 12KWof memory, 3 x serial ports and a posibus interface. Alas there were no disk packs with the RK05s although I do have one 16 sector pack (unique to PDP-8s)

The machine was owned by a local company who had it in the basement of their country house and they were the owners from new. Removal required us to get the machine up a very steep and narrow staircase and so we had to dismantle the machine considerably in order to get it out. Careful notes and pictures were taken to aid in reassembly.

The machine is going to get pride of place in my office alongside my PDP-11/70 and PDP-8/Ms.

My second PDP-8/M is just about back in the land of the living. I followed largely the same process as with the restoration of my first 8/M. Luckily this examples case wasn’t corroded and so I didn’t bother respraying and left it in original condition.

The main sticking point with getting this machine back was a failed +5V and +15V rail on the PSU. Being no expert on PSUs and having been mildly ‘warning’ zapped by it when I decided to see if anything obvious was failed, I had a hunt for a company to perform the repair.

I opted for Electronic Repair Centre Limited after some internet searches. I was very impressed with their service, which was fast and very well priced. I thoroughly recommend them to anyone looking to get a power supply repaired.

After getting the PSU back, I reassembled the machine and with a bit of CPU board swapping (3 of the originals turned out to be failed), I now have a mostly working machine. The one gotcha I currently have is that on entering the DEC accumulator counting test, the accumulator counts at full bore and cannot be seen neatly increasing on the console. My suspicion is that the line time clock might be the cause of this.

The investigation continues…

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