Enter the IMSAI PCS-80/15

| No Comments

Craigslist can be an amazing resource - you just never know what will turn up.

While browsing through the vintage computer listings on Craigslist this afternoon, I stumbled upon a free Kaypro II system. It was by just chance that I found it; I normally I search on keywords like “vintage computer”, “museum computer” or a mixture of brands (Atari, Commodore, etc.) For some reason I tried “Kaypro” this time, probably because I hadn’t gotten any hits on anything else for a while.

The Kaypro II post was already three days old. I figured it was probably long gone since it was free, but I wrote anyway:

“Hi - I don’t suppose the Kaypro is still available?”

The response came back quickly. “Why, yes it is! :) Let me know…”

After a brief phone conversation for directions and the best time to meet, I drove down to Los Altos to grab it.

When I arrived, the seller already had the Kaypro II set up on a bench outside his garage. He powered it on and showed me the boot screen.

He mentioned his wife had thrown out his diskettes at some point, but the Kaypro II CP/M 2.2 system and MEX114 (ModemEXecutive) communications diskettes were still loaded in the drives. Sweet!

“So, why did you want the Kaypro?” he asked.

“Well, I’m a CP/M fan - I’m always looking out for fun hardware to play around with,” I responded.

“And you didn’t want the S-100 system?”

I froze. “S-100 system?”

“Yeah, I advertised an IMSAI S-100 system on Craigslist too, but before you wrote no one had contacted me about either one. I offered the S-100 to the Computer History Museum, but they told me they already had several examples. Do you want to look at it?”

“Oh definitely, that would be great! Are you asking anything for the S-100 stuff?”

“Oh no, I just want to get it out of here. I have too much junk in my garage as it is and it would be a shame to take it to the dump.”

We headed back behind his garage where he had the IMSAI stored. It was a massive machine with a hand built, 8” drive tower. He mentioned that this system had belonged to his father in law and that he had hand built the memory cards.

So what started as pretty cool if low key mission to pick up a free Kaypro II turned out to be an amazing find. I’ve wanted an S-100 system for nearly twenty years, but they always seem to go for “Captain Insano” cash. Even the reproduction kits are extremely expensive. I’m still giddy over this!


When I got the IMSAI home, I did a little bit of exploration. Inside, there’s a label and Post-It note which seem to indicate it was once sold at a hamfest or swap meet: “Make offer - all or parts” and “Most docs avail.”. There was also a S-100 card and spare oscillator in an anti-static bag tucked in front of the installed cards, which may have been purchased at the same time and simply stored. The power cable was also stored inside the system.


The S-100 backplane is a massive 19 slot Thinker Toys Wunderbus. I tried pulling some of the cards to get a better look at them, but they’re pretty well stuck. I don’t want to break things this early in the game so I’ll come back to those. From what I can see, there are a couple 32K memory cards, I/O, floppy controller, CPU, etc. - around eight cards aside from the one in the bag.


The drive tower consists of a combination metal/wood chassis with three bays. The bottom two bays hold Shugart 8” drives, and the top bay is a storage compartment which also hides some control switches. It currently contains the unit’s power cord. The builder added some extra moulding to the door to make the compartment resemble one of the Shugarts. The whole thing just reeks of geeky homebrew retro goodness.



I’ll explore the system more as time allows - I don’t want to jump in without cleaning it throughly and making certain it won’t explode when powered on. I’ll also need to track down software for it which should keep me busy for a while.

Fun stuff though; I’m psyched!

Leave a comment

About this Entry

This page contains a single entry by nekonoko published on September 18, 2008 10:42 PM.

Installing Atari Rainbow TOS was the previous entry in this blog.

Other Projects and Poking Around the Kaypro II is the next entry in this blog.

Find recent content on the main index or look in the archives to find all content.