Welcome to the Living Computers blog! From oral histories and engineering restoration updates to behind-the-scenes looks and more, you’ll love the unique and personal stories we share with our community. Start exploring and get to know our team!

Show All
Life with a 51 year old CDC 6500
December 11, 2018
by Bruce S.
The CDC 6500 has led a rough life over the last 6 months or so: way back on the afternoon of July 2, 2018, I got an email from the CDC’s Power Control PLC telling me that it had to turn off the computer because the cooling water was too hot! A technician came out and found that the chiller was low on refrigerant. He brought it back up to the proper level, and went away. Next morning it was down again. ...
August 8, 2018
by Rich A.
As anyone familiar with LCM+L knows, the museum initially grew out of Paul Allen’s personal collection of vintage computers. Many of the larger systems in the collection reflected his own experiences with computers beginning in when he was still in high school. Among the systems he used then were System/360 ...
July 2, 2018
by Keith H.
My last article explained that the DEC 340 Monitor pointed at and shot dots from an electron gun to light up spots on its screen. That was my magic chant, the method of how the DEC 340 drew its pictures as a collection of dots. Every picture a DEC 340 ever showed was made of dots flashed onto its radar tube ...
June 23, 2018
by Keith H.
Previously I introduced my DEC 340 monitor restoration project. I promised then to describe how the DEC 340 monitor worked. I will, but that explanation won’t mean much without some context first. After the context the special magic that makes the DEC 340 different from other computer monitors will be revealed. High ...
June 7, 2018
by Keith H.
My big project this year is to get a DEC 340 monitor working. Here is a picture of one of them. The DEC 340 was a very early and rare computer monitor dating from the mid 60’s used of course, on DEC computers, their PDP series. Two cabinets of rack mounted electronics. The 340 is historic and was used ...
May 2, 2018
by Bruce S.
I have 4500 modules in the CDC 6500, and it isn’t always easy to debug them in the machine, because convincing the machine to wiggle its lines so I can check each transistor on a particular module is difficult. In order to make this problem a little easier, I have built a cordwood module tester. It has taken a ...
April 27, 2018
by Jeff K.
Minecraft is getting a little stale for me now. I’ve done my exploring, and exploiting. Nothing left but… to look at the database! Each Minecraft world has its own folder in the save directory, with other subfolders and a lot of data files. I noticed that each map created in the world is a separate file, and that file is in GZip format ...
April 26, 2018
by Jeff K.
The IBM360/30 gets stuck in a microcode loop. The documentation indicates that a branch should be taken if the Z-bus is zero, and the branch should be taken. The branch is not being taken. A previous annoyance was that the microcode would stop at address 0xB46. As the documentation indicates for that location, ...
April 18, 2018
by Bruce S.
Five years ago, when we were getting done with restoring our PDP10-KI, we were running out of working disk drives to run it from. We were down to one set of replacement heads, two working drives, and we didn’t have a source for new ones. We found some folks that said they could rebuild the packs, but it turned out ...
February 1, 2018
by Bruce S.
When we last left our hero, he had re-soldered all the Via rivets on one of the 510 “PS”, core memory sense amplifier modules in the CDC6500, and the machine was working. That lasted about a day, and the memory went away again. What was wrong this time? You guessed it, bit 56 in bank 36 was bad again. Third time ...
January 29, 2018
by Jeff K.
The IBM360-30 uses Printed Card Capacitor storage for microcode. The cards were created by printing Silver ink on Mylar, or etched copper. 304 cards make up the microcode. I scanned them all. My procedure was to remove one card, clean it, scan it, and then replace it before removing the next card. My original ...
Show All
Filter by Topic

Filter by Author

Filter by Year