Registry of Remaining Kenbak-1 Computers:

List of All Remaining Original Kenbak-1's:

Around 52 original machines were manufactured including the prototype and the machines sold by CTI Educational Products (see our FAQ page for this estimate.) Currently, 14 of these 52 original computers are known to still exist.

Purpose and Naming Conventions:

This list has 5 aims:

List all computers believed to exist.
Track ownership history (provenance) and location.
Record description and photos to identify and differentiate computers.
Establish names or "nicknames" to standardize communication.
Track any "non-verified rumors" of a new or lost computer.

For nicknames we use the person who owned and preserved the computer through the 80's when most likely to be lost, rather than current owner. Multiple nicknames and serial numbers are sometimes appropriate.

Red dots show the location

of known original Kenbak-1's

The List:

1) Prototype (John1):

Provenance: John Blankenbaker kept this until 2015 when he sold it by Bonham's Auctioneers in 2015 for $31,250. It was purchased by a California retailer of scientific and technical artifacts who listed it for $65,000 in their catalogue, then eventually sold it to Achim Baqué of Germany (in the Cologne Bonn Region) for $41,250. More details on provenance are <HERE>.

This first prototype was very different from "production" machines. Printed circuit board is labeled "Kenbak 10000 Rev" (without the "A" or "B") and many jumpers/corrections on the PC board. Power supply and front panel graphics are different, and no "lock" switch. The store button is a red "enter" button. Since this photo, Achim had Blankenbaker autograph the top. Many pictures, and a story is at his "thefirstpc.com" web site. (Photo courtesy Achim Baqué of Western Germany.)

2) Serial #216 (John2)

Provenance: Kept by John Blankenbaker until 1986, when he donated it to "The Computer Museum" in Boston". In 2000, when they closed, it was transferred to the Computer History Museum in Mountain View, CA. While serial number suggests it was the last machine made, it is actually one of the first, with a "Rev A" circuit board. More details on provenance are <HERE>.

Recently replaced aluminum handles (2/23), It's been on public display now for almost 40 years. A link to the display is HERE. This is one of two "Revision A" circuit board computers, an intermediate between the prototype, and the production computers.

3) Serial#183 (John3)

Provenance: Assembled circa 1972, it didn't work until 5/2010 when John fixed it and sold it on eBay. It was purchased for $25,600 by a collector in Monzo, Italy, who resold it via eBay in February 2016 for $35,000. It's now owned by a collector in Massachusetts shown online at www.oldcomputermuseum.com More details <HERE>.

Great condition. All lights were replaced with a modern substitute, one aluminum handle was replaced. There are some modifications to the memory clock driver circuits, as Blankenbaker thought he found an error. Read more about that bug and fix <HERE>

4) Crosley (Serial #197)

Provenance: Tom Crosley, an engineer/computer scientist purchased this new in 1971 directly from the Scientific American ad, and used it extensively while in grad school. He even added a teletype input interface. In 2004, he sold this on eBay and Eric won it for $2000. Erik posted extensive information on his "www.vintage-computer.com" website. Bob Roswell of The Computer Museum @ System Source, outside Baltimore, acquired this in 2024 from Erik. Click <HERE> for more provenance details.

This was the first Kenbak-1 documented on the internet with high-resolution photos of the internals. This computer has an unusual modification, where a chip was placed in IC99 location (normally empty) with jumpers into the circuit. Tom Crosley explained that it was for an ASR-33 teletype interface he made, to help enter programs. John Blankenbaker's autograph is inside the top cover.

5) Nielsen1

Provenance: One of 8 computers preserved by Robert Nielsen, owner of Nielsen Electronics Institute. He traded this to Herbert Eisengruber of the "Nova Scotia Computer Museum" in Canada for a used laptop in April, 2003. This was sold when the Museum closed, to a collector in Middleton, Nova Scotia, who sold it on eBay around 2019. It appeared lost until acquired by the Computer Museum of America late 2022, as the first Kenbak-1 directly owned by the museum, not just loaned by the founder. Not on public display. More details on provenance <HERE>.

A muffin fan was mounted on back, outside the case. Branded CTI. This is the first sold by Nielsen (and Eisengruber) so possibly the least coveted due to the fan modification. (Photo courtesy Computer Museum of America.)

6) Nielsen2

Provenance: This is the second of the 8 computers preserved by Robert Nielsen, who wrote about how the old switches were replaced with these momentary toggle switches. This was part of a lot of 6 computers sold to the Nova Scotia Museum soon after they got his first. When the museum closed, Herbert sold this to Lonnie Mimms, founder of the Computer Museum of America in Roswell, long before the museum opened. This likely remains in storage, and has not been on public display. More details on provenance <HERE>.

The blue modified buttons are the main distinguishing feature. Nielsen wrote how the buttons were replaced in hopes of improved durability. It has holes on top like all the Nielsen machines. (Photo courtesy Herbert Eisengruber)

7) Nielsen3 (Gray Case)

Provenance: The 3rd of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 to the Nova Scotia Computer Museum. When that museum closed, Herbert Eisengruber sold this to the current owner in 2009. More details on provenance <HERE>.

This is an interesting computer, even without the gray case bottom, or the CTI serial number sticker. This has a "Revision A" circuit board, an intermediate between the prototype and production models, which John made after the prototype.

8) Nielsen4 (Serial #185)

Provenance: This is the 4rd of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 to the Nova Scotia Computer Museum. When that museum closed, it was sold to Vinal Applebee, who was planning the "Maine Computer Museum" which never materialized. It was auctioned by Germany-based "Auction Team Breker" on November 7th, 2015 for 41808.78 Euros including fees (about $46,000 at the time) to the Munich museum. (Deutsches Museum, Munich). More details on provenance are <HERE>.

Nielsen #4 Kenbak-1 in Deutsches Museum, Munich

Identifiable by some distinct scratches in the top of the case and a dent in back near fan (dent suffered after Nova Scotia, before Breker). (Photo courtesy Maksym Kozlenko, Creative Commons Link here.)

9) Nielsen5

Provenance: This is the 5th of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 for to the Nova Scotia Computer Museum. When that Museum closed, Herbert sold it around 2008 to an unknown buyer. This is the only computer in this list without a known recent owner or location. More details on provenance <HERE>.

Herbert said that a couple buyers wanted to remain anonymous. Persistent hounding has not revealed more. (Photo courtesy Herbert Eisengruber)

10) Nielsen6 (Serial#194)

Provenance: This is the 6th of the 8 computers preserved by Robert Nielsen, then sold as a lot of 6 to the Nova Scotia Computer Museum. When that Museum closed, Herbert sold it around 2008 to an unknown buyer, and eventually was bought by Lonnie Mimms, founder of the Computer Museum of America, in Roswell, Georgia. More details on provenance are <HERE>.

Nielsen #6 Computer on display at Computer Museum of America

When this was acquired from Nielsen, this had a foil "CTI" label over the Kenbak-1 logo, but that was removed by Eisengruber. It's on loan to the museum by it's founder. (Photo permission courtesy CMoA)

11) Nielsen7 (Big Holes)

Provenance: This is the 7th of the 8 computers preserved by Robert Nielsen, and the last of the 6 sold to the Nova Scotia Computer Museum. When that Museum closed, Herbert sold it around 2008 to Wigton Museum/Timeline Computer Archive, which has a world-class collection, but is still fundraising for a permanent display location. Currently, most of its artifacts are in storage, with occasional pop-up displays. More details on provenance are <HERE>.

Nielson #7 computer, at Wigton Museum, Carlisle, UK

No rear labels or serial number, it's the only specimen that had very large holes in the top cover, which helps in identification. Great YouTube video <HERE> and the museum's Facebook page is <HERE> (photo permission courtesy Mike Armstrong, Wigton Museum)

12) Nielsen8 (Serial #203)

Provenance: This is the 8th of the 8 computers preserved by Robert Nielsen, and the last he sold, after selling the first 7 to the Nova Scotia Computer Museum. After failed eBay auction, this sold in May 2011, for $20,000, along with other memorabilia, to Lonnie Mimms, founder of the Computer Museum of America. More details on provenance are <HERE>.

Nielsen #8 Kenbak-1 computer, in storage, Roswell, GA

This YouTube video has Robert Nielsen showing the inside and running it. This seems to remain in storage and has never been on public display. (Photo courtesy Robert Nielsen.)

13) Serial #212 (Seattle)

Provenance: Unknown. Based on blemish on top of case, the hex screws, and the "hanging" angle of the read and start buttons, this is the computer which sold on eBay August 1, 2005 for $10,850, from AuburnAlabam to CollectRHC. With the closing of the LCM, this was sold at an astronomical price of $166,055 after fees and taxes (CLICK HERE). Current owner is unknown.

Serial #212 Computer at Living Computer Museum, Seattle, WA.

One blemish to left front cover paint, replacement "hex screws" in front panel. Aluminum handles on sides seem to be attached with bolts and nuts, rather than set screws.

14) Missing Light

Provenance: Unknown. The earliest photo of this machine was a April 10, 2014 Facebook photo. In 2016, this computer was shown at a "Pop-Up" display at the Vintage Computer Festival (VCF Southwest 4.0) where they had a surreal "Red Shrine Exhibit" of the Kenbak-1. Possibly only used in traveling or "Pop-up" displays since only the number 10 machine (Neilsen6) seems to be on permanent public display.

Kenbak-1 Computer (Red Shrine) in storage in Roswell, GA.

Very little is known about this, as only a few photos have been found. (photo permission courtesy CMoA)

Possible Other Unlisted Machines:

There has long been a rumor that an anonymous collector in Tennessee has a Kenbak-1, but details are unknown. This rumor goes back to at least April 2006, predating the sales of the Nielsen/Eisengruber computers, so unless it was sold on eBay in 2005 (Serial #212) or given to the Computer Museum of America in Roswell (MissingLight) it very well could be a true 15th original Kenbak-1 computer. But this remains unverified.
There was a rumor that two Kenbak-1's were found in Canada, in the possession of an owner who has had them for years, but supposedly the family didn't want details public while they consulted lawyers to transfer property to a trust. However, since this rumor began around August 2022, and several years have passed without more details, it seems increasingly doubtful.

Additional Information about the 14 Known Original Kenbak-1 Computers:

For a Comparison with details and differences of the 14 known computers, see the Comparison of The Original Kenbak-1 Computers which compares motherboards, and deduces date of manufacture.
For more information on the provenance (prior ownership history) click on Provenance Details of some original Kenbak-1's.
For photo database of all above computers, click on the photograph of the computer, or the number of photos link.

Prices of Original Kenbak-1 Computers:

Buyers don't like to talk about prices they pay, making this information sensitive. All of the following auction information has been publicly available on the internet. And any private sale amount is only included here if several sources repeated it, proving it's not a secret.

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