Crazy Eddie's Used Computers

That display is supposed to be an "X" and something has gone terribly wrong. Passes control logic diagnostics, should be fun to debug.

The Lab-8/e's VC8E point-plotting controller is mostly functional, as is the Tektronix 603 scope it's connected to. There's a stuck bit in the Y DAC and something very odd is going on with the X DAC. The scope stores a bit when it's not in Store mode, so that'll need some work, but the effect is kind of cool.

Found this really cool EduCalc Model 25 GD at a local recycler today. It's an HP-25 scientific/programmable calculator with a large Panaplex plasma panel grafted onto it. (There's also a handsome wood case involved.) The intended use was in the classroom; a teacher could use this calculator on a desk in front of a class of students, and the display would be visible to the class.

This Lab-8/e system belonged to a UW chemistry prof, he developed his own variant of Focal ("UW Focal") on this machine and used it to control various laboratory instruments. I'm hoping to get it all running this summer. Just working on getting it all installed in the rack right now, to free up some floor space in the garage!

Just acquired a very nice set of DEC documentation and man, there's some pretty stuff in there. I'm going to be busy with the scanner this summer...

A photo from another universe (April, 1973). From left to right: Larry Clark, Chuck Thacker, Alan Kay, Ed McCreight, and the first operational Xerox Alto ("Bilbo"). Taken on the day the machine came to life.

And we have achieved Smalltalk-80.

@kirtai@tech.lgbt Interlisp-D, Smalltalk-80, and Cedar were all options for this system and I'd like to try them all but Cedar's the one I'd really like to get running: https://www.youtube.com/watch?v=z_dt7NG38V4

Made some good progress with the Xerox Dolphin this week. Got the console sorted out with new capacitors and a ton of cracked solder joints fixed up, and got the Shugart SA-4008 drive working again just by cleaning a few connectors -- it boots from disk into the Alto Executive. Backed up the drive over the network using Copydisk. Interlisp starts but hangs a few seconds after loading microcode.

I finally found a workable yoke for my Xerox 1100 (Dolphin)'s console display and I am extremely excited to get a picture out of it (even if it's way too wide and off center... it'll take some tweaking to get it right). The Dolphin was the first system made by Xerox's System Development Department (SDD). SDD later made the Star workstation. Here's a couple of photos of it booting the Alto Net Executive off of the 3mbit Ethernet interface and running a small demo that displays Dave Boggs's face.

Mark your calendars: The return of the Vintage Computer Festival: Pacific Northwest is only a month away! I will see you there or you will be square! https://vcfpnw.org/

@icm@mastodon.sdf.org Looking forward to commencing work on this thing, it's neat!

I went down to @icm@mastodon.sdf.org today to scope out the LINC-8 for restoration. It looks to be in very good condition (some dirt/rust on the top bits notwithstanding) but there's one wrinkle: this system came from Australia and thus it wants 50Hz AC. The LINC-8 uses the same 708 power supply as the PDP-8 but with a different ferroresonant xformer for 50Hz (the supply is designated "708A"). Fortunately we have a parts 708 supply to steal from. The AC motors in the LINCtape drive are another story...

@peterrenshaw@ioc.exchange @icm@mastodon.sdf.org It's an X200s that I got out of a free pile at a local event a few years ago. Nothing fancy but it's small and it has the extended battery, which still works great!

The 11/70 is a fun system to work on. The service documentation is excellent and you get to work thorough fun diagrams like the one below, which traces through all execution paths of the microcode (all 256 words of it). 14 such sheets cover the entire microcode, which implements the entire PDP-11 instruction set as well as front panel operations. (With a lot of help from the hardware, of course.). Each box in that diagram describes what a single microcode word does when executed.

I went down to @icm@mastodon.sdf.org to work on Miss Piggy, their PDP-11/70 system. Any instruction that touched memory would wedge the processor (though front panel accesses worked OK). Brought along my KM11 diagnostic set to help diagnose the issue and traced it down to a faulty microcode ROM (one of several early bipolar 256x4bit PROMs in the system). We had a spare ROM board so we swapped that in; chip-level diagnosis will happen at some later date. The system boots 7th ed. UNIX once again!

Over the holidays I started work on an emulator of the General Automation SPC-12 minicomputer (a computer I've become lightly obsessed with over the past few months). I transcribed a listing of "BUS-II" (Basic Utility System) from the manuals and I finally had time this week to work out the remaining kinks in the emulation. Behold, BUS-II in action for the first time in who knows how long: